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D D C

D EUTISIÜJ

DDC-IRA B

§andia Corporation Contractor for U.S. Atomic Energy Commission

ALBUQUERQUE, NEW MEXICO LIVERMORE, CALIFORNIA

■ C 1003 OJ (•-621 ffiM dsO ^J ITS

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\I:H()-TIII:KM()I)VNAMICS

/ y

t SC-RR-64-U79

THE HYPKHSONIC PLASMA fONVKRTKH;

K. .1. Touryan, 742 1 - 1 Sandia Labor.itory, Albuquci'qut

Nuvfniber LH>4

ABSTRACT

As a (.ontmuatioti to Part I of the hypt'rsonu plasma gencratoi known as ASP (Aerodynamic Supply of Power-), experimental analyses have been extended to investigate in detail the various parameters that govern the operation of the generator. A final feasibility study was made, and possible modifications to the theory are outlined. Test runs m the Sandia Corporation are jet with air as the working fluid at 12, 000 BTU/lb have generated 8 amp/in short circuit currents and 2. 3 volts open cir- cuit voltage. Under" favorable conditions, full-size re-entry vehicles m the altitude range of 200, 000 to 80, 000 feel are expected to yield several kilowatts of power-.

Published as SC-4960(RR), date January 19()4.

ACKNOWLEDGMENTS

The author is indebted to P. T. Lübeck for his help collecting and reducing the data and supplying the arc jet operation character- istics. Special thanks are extended to Messrs. G. M. Baker and J. V. Williams for operating the plasma jet, and to Mr. W. Ilaskell for designing and procuring the models. Dr. W. Byatt and Captain G. E. Weinstein, of the University of New Mexico, helped in the initial stages of the ASP generator development.

Issued by Sandia Corftoratlon, a prime contractor to the

I'nlted States Atomu Knerg> CommlBslon

LEGAL NOTICE Thia report »as prpparpd as an account of Government sponsored work.

Neither the I'nlted Slates, nor the Commlasion, nor any person acting on behalf of the Commlsiton:

A. Makes any warranty or representation, expressed or implied, with re- spect "o the aniiracy, completeness, cr usefulness of the information contained in this report, or that the use of any information, apparatus, method, 01 •irocran disclosed in this report may not infringe privately owned rights, or

B. Assumes any liabilities with respect to the use of, or for damages re- sulting from the use of any Information, apparatus, method, or process disclosed in this report.

As used in the above, 'person acting on behalf of the Commission* includes any employee or contractor of the Commission, or employee of such contractor, to the extent thai such employee or contractor of the Cor. Tiission, ur employee of such contractor prepares, disseminates, or provides actesn to. anj information pursuant to his employment or contract with the Commission, or his employment with such contractor.

Printed in USA. Price $1, 00. Available from the Office of Technical Services, Department of Commerce

Washington 25, I) C .

TABLE OF CONTENTS

Tables

LIST OF TABLES

Pace

List of Symbols "

Introduction ^

Theory 1Ü

Experiments ^* A. Test Conditions 11 Ü. Parameters Influencing Generator Output 20 C. Experimental Results 21 D. Optimum Results 30

Free Flight Conditions 3G

Future Work 36

Appendix 41

List of References 47

1 Electron Density in Argon Gas IB

II Electron Density in Air lit

III Model Dimensions 22

IV Open-Circuit Voltage 23

V Output with and without Seeding 25

VI Model Materials ;)0

VII Optimum Output per Emitter Area 3-i

3-4

LIST OF ILLUSTRATIONS

Figure page

Frontispiece A Hypersonic Plasma Generator 8

1 Schematic of ASP Generator 9

2 Sketches of ASP Plasma Jet Models 12

:i Surface Pressure on S-6 Model t,. 160 kw Jet (Argon) 13

4 Kinetic Temperature Near Body of S-6 Model in 160 kw Jet (Argon) 14

5 Surface Pressure on S-6 Model in 160 kw Jet (Air) 15

6 Surface Pressure on S-6 Model in 160 kw Jet (Air, Nose Cone Section Enlarged) 16

7 Kinetic Temperature Near Body Surface of S-6 Model in 160 kw Jet (Air) 17

8 Short-Circuit Current Versus Fmitter Area for Two Values of Effective ß. Runs Made in Argon Gas with 5000 BTU/lb Energy, and Nitrogen at 12,000 BTU/lb 20

9 Output from Geometrically Similar Models with Different Fmittcr Areas 22

10 Power Output for Various Model Geometries at Constant Jet Energy 24

11 Degree of lomzation on Short Circuit Current Output. Argon-Nitrogen Mixtures. 26

12 Short Circuit Current versus Electron Density (Unseeded Gas from Spectroscopy, Seeded Gas using Saha Equation) 26

13 Power Output and V-I Characteristics of S-6 Model in Argon, Nitrogen and Air 27

14 Dimensionless Short-Circuit Current versus l//i for Various Resistance Parameters C, in Argon and in Air 2(J

15 Output Data for ß = 0. 15, VT = 1 ev, I = 0. \ from S-6 Tungsten Model in Argon at 5000 BTU/lb ' 31

16 Power Levels from Various Models Showing the Effect of Argon Gas Energy on Output 31

17 Voltage-Current Characteristics for V = 1.0, Various /^ and 4 Values in Argon Gas 32

18 Effect of Contact Resistance between Pyrolitic Graphite Shell and Carbon Substrate on Output 33

19 Dimensionless Maximum Power versus i for Various Values oi ß and r. 35

20 Electron Density and Kinetic Temperature Near Stagnation Point for Blunt Re-entry Vehicle at Various Altitudes 37

21 Electrical Conductivity as a Function of Temperature for Equilibrium Air at Various Densities (Equation U-5, Reference 1) 38

.IST OF SYMBOLS

A (or A ) - emitter area v e m

A - collector area c

C - °HIth/(<7 VT)

D - diffusion coefficient

E - ernf or electric field (volts)

-19 e - electronic charge 1. 6.0207 x 10 coulombs

h - Planck's constant

I - current (amperes)

1 ' ^th

i - I /I , (short circuit current) sc sc th

j, J - current density, amps/in

k - Boltzmann constant 1. 3709 x 10 erg/deg

L - characteristic length

m , m. - electronic and ionic mass, respectively e i

P - power (watts)

p - pressure

K - emitter radius

r - resistance

r , i , r, - plasma, contact, and load resistance, respectively p c L

T - electron temperature e

T - emitter surface temperature em

T - collector surface temperature

v - velocity

V - potential (volts)

V - open circuit potential oc r r

V - plasm i temperature equivalent potential

S i..

LIST OF SYMBOLS (cont)

VT- - emitter temperature equivalent potential em

V - emitter sheath potential em

V - collector shenth potential c

Greek Symbols

a - a fraction in definition of C

ß - I /I ~ A /A eem ec enr c

7 - 1. /I a 1/155 for air ic ec

th eem

6 - dielectric constant

9 - spherical coordinate (in Appendix 0 = kT /e)

/i - mobility

a - electrical conductivity mhos/cm

T - time

0 - work function (in Appendix B and C, 0 = potential)

••

fi

Frontispiece. A I lypcrsonu; I'lasnu (iinn ,,i of

Till-. HYPERSONIC PLASMA CONVKHTER

Introduction

Thr opcr.it ion.il pruu-iplc of the hvporsonic pl;isni;i gcmTator has been discussed in dcl.nl .1. I'.,it I

( Hili r« 111 i- 1 ) of this two-part report. Hncflv, the nose cone of a rc-cntr\ >> chicle serves ,i> 1 the I'm 1 on u

emitter ul electrons, or a cathode (see Kigurc 1). Thesi1 electrons are then conducted through tin .-Im k

ionized stream, increased in kinetic energN In collisions, and collei ted over the relatively i ool vehn le

afterbods «huh is electrically insulated from tlu nose cone and whuh serves as an anode, 01 .1 c olli i tor.

A load conneeted between the cathode .uid the anode within the vehicle complete,- the cue uit, 1 lit L'I IH rator

has the basic features of a plasma thermocouple and, for its power output depend- primanls 011 tin KUIM

temperature and area differences between emitter and collector', v«. ith the kmetu energs ol (he pl.ism.i

electrons as its energy source.

SHOCK IONIZED AIR

EMITTER

Kigure 1, Schematic ol AM' (em rator

In addition to the several references mentioned in Helerence 1, two mon v\ inks (Kelt n ru 1 s .' iml i I

ha\i been published recentl\ which de.il with the ASI' generator. The first work ,-umm,i r 1/e.- thi 1 ii;h pumt.-

ol both Keli rent 1 1 and the present report. The si cond work -11111111,1 n /i s the progn .-- n por' - ■ 1! tin A ork

dorn bs tin l.lei tncal I aigirH'cnng Department of the L'M\ersils ol New Me\u o on .1 cuntr.u t n ith S.u.di.i

t'oi'poration starting .lanuars 1U6H ,md ending .June l! 14.

Ttu-ory

!-'or a lull treatment of the theory of the plasma generator the reader is referred to Reference 1 and

several references quoted therein. We repeat briefly the salient points in its development, the space-

charge neutralized volt-ampere characteristics (V < 0, V -emitter sheath potential) of the generator em em

can be represented by Equation 5 from Reference 1, or,

m - 1 /i,1 • • ec / th lem

1 I 1 »- I eem \ lc

M0 - 0 ) - Ir (1)

where

T - electron temperature e

random electron current to collector

1 - random electron current to emitter eem

th - thermionic emission current

- random ion current to emitter

I - random ion current to eollec tor ic

0,0 - work functions of emitter ,ind collector respectively' e c

r(r , r ,r, ) - circuit resistance (plasma, contact .mdload) p c 1.

The open circuit voltage then become!

V.,. In 0 - 0 (2)

wiiere, there has been ;• 'roduced tin' notation of U'aymouth, Reference -1. or

I'. I 1 eem ec

", -- 1 /I ic ec

th eem

V, - voltage equivalent of plasma electron temperature

For V > 0(e. g. 4-1), Equation 2 changes to em

V = V' /n ii-, <- V In 1/-, ' 0 - 0 oc I em t e c

( I)

V - voltage equivalent of emitter temperature Tem

>

The short circuit current, on the other hand, follows by setting V = A0 = 0

I r = V /n sc T

1 ^ l^sc (•1)

where i - nondimensional current I /I , . s c s c t n

For zero resistance. Equation 4 can be simplified to yield (Reference 4)

th sc 1 •- ß

(5)

or if back emission from the collector I1, is included th

'sc^'th-1;,^11^ (G)

It should be noted that the basic volt-ampere characteristics equation above has been derived on tlv

basis of a rather unrealistic assumption of constant electron temperature around the vehicle and a constant

electron density. As will be shown later, the gas temperature in the flow field changes approximately

40 degrees while expanding over a 12-degree hemisphere cone. Electron densities can decrease by as much

as three orders ot magnitude from emitter to collector. 1-urthermore, because of large currents 2

(20-i0 amps/in ) being dumped m the plasma jet, joule heating and Thompson effects may become prominent

m disturbing the plasma temperature distribution. These and other modifu ations necessary for refining the

AST generator theory are discussed m detail in the Appendix.

Experiment s

To verify the analytical predictions of the hypersonic generator, an extensive set of experiments were

performed m the Sandia Corporation 160 kw plasma art tunn"'.. The v.inous model geometries used in the

plasma tunnels are shown in Figure 2.

A. Test Conditions

The average diameter of the models and of the plasma jet was 3/4 inch and 1-1/4 inches, respeetively.

The details of the flow field around an S-6 model in the 16Ü kw plasma jet, with argon and air- .is the working

gases are presented graphically in Figures 3 through 7 and tabulated in Tables 1 and 11, As observed from

this data, the average flow Mach number is 2. 5-3, 0 with mean energy inputs to the jet ol 5000 BTU/lb for

argon and 12,000 BTU/lb tor air (or nitrogen). The ambient pressure in the test chamber is ol the order

of 7 mm ( 0. 01 atm) and stagnation pressures range from 0. 06 to 0. 13 atm. Figure 7 shows the equilibrium

and nonequilibnum calculations of the temperature in the jet for air at various energy inputs over a

1 1

EMITTER

^/U\\\\\\\\\\\W^W^^ / /} f I N'T I ! I t I I I t I I 1 ! ] I I I I I I I I

1 •^~ [NSULATOR 'COLLECTOR

MOUNTING STIN(

(a) Model S-0 (Typical Cut-Out)

VAl^IABLE LOAD R.

(c) Model S-30 Mudel S-IO

(d) Model U-10

Q /

c

(c) Model U-0

IN ABOVE E = EMITTER C = COLLECTOR INSULATOR

.Ulli ' _' >Ki t. IM - Dt \M ' rl^MIM .U t \ici(li

;

.150 -

125

3.000 HIT 11. ,5,500 Mil :b ,8,000 inr lb

Axial distance (in)

l-'igurc 1. Surf,n i I'n .-.Min- on S-ti Model m !<>() k^ ,Ii t ( \r^on)

l.i

12.000 -

9,000

8,000 MIT 11.

5, 500 MIC 11.

a.

3 —' t

o H

6,000

3,000 -

3.000 UM 11.

A.xial distance (in)

Figure -1. Kill' ti. I'i rnpi iMtui . \V,,r Hod. Moili 1 ,1, IM» KV. .1. • ' \l U'.l.)

1 i

,075 -

s <

u 3 en

.050-

.025

14,000HTL lb /12,000 HTLJb ,8,000 HTL'/lb

Axial distance (in)

igurc 5. Surface I'ressure on S-(i Model m lliO kw Jet (Air)

B

14,000 M ;i 12,000 Hi i 8,000 mi

T

0.6

Distance (in)

-1—

0.8 1.0 —i—

1 2 1.4

li^uic (I. Surf.M ' I'n .-.>iui oi. ^■,' Modi 1 m IMI kw I' ' ( \ 11■ \i)M C unc Set t 11111 ).n 1 i ru i ii)

8,000 14,000 BTU/lb

12.000 BTU/lb

X

u a

a E o

6.000 -

4,000 -

2,000 -

^

8.000 BTU/U /

14,000 BTl'/lb

(nonequilibrium flow)

3 4

Distance (in)

Kiguri1 7 Kint'tic TfrnpLTaturc Near Bod> Surfaci1 ot S-ii Modt'l in KiO k'A Ji-t (Air)

TABLE 1

i: If et i-on Density in Argon Gas

Distance (Axial) L/iL

0

0. 125

0. 207

0. 750

0, 2 x 10 .15

x 10 M

.13 3. 7 x 10

3. 75 x 10

3000 BTU/lb

10 17

3. 75 x 10

1. 78 x 10

Iti

1. 77 x 10

16

16

G. 2 x 10

1. 39 x 10

2.08 x 10"

-2

2. 12 x 10

0

0. 125

0. 210

0. 750

5500 BTU/lb

B. 3; 5 : x 10'

5. 5 X io15

6. 3 X .o14

15 16 6. 8 x 10

2. 02 x 10

1. 06 x 10

5. 5 x 10 14

9. 00 x 10

16

15

1.23 x 10

2. 7 x lü"1

5. 95 x 10'

(.. 1 x 10"~

-1

8000 BTU/lb

0

0. 125

0. 2 07

0. 7 50

1. 15 x IO15

3. 05 x IO1'

3. 0 x IO15

io15

3. I) x 10

1. 4 x lü'

5. 8x10

5.2 x 10'

P

15

15

2. 95 x 10

2. 16 x 10

5. 19 x IO'

1. 92 x 10

-1

- 1

- 1

18

TABLE II

ICIectron Density in Air

Distance (Axial) e/n.

0

0. 125

0. 2 07

0. 750

B, 000 BTU/lb

6. 15 x 10

9. 25 x 10

3. 48 >; 10

3. 08 x 10

.13

12

12

12

6. 4 x 10

2. 5 x 10

16

16

1. 25 x 10

1. 14 x 10"

16

.16

9. 6 x 10 -4

3. 7 x 10

2.8 x 10

-4

-4

2. 7 x 10 -4

0

0. 125

0. 207

0. 750

12, 000 BTU/lb

2. 58 x 10

5. 03 x 10

1. 43 x 10

1. 16 x 10

14

13

13

13

6. 0 x 10 16

2. 35 x 10

1. 20 x 10

1. 08 x 10

16

1(1

16

4. 3 x 10

2. 1 x lO"'

1. 2 x lO'^

1. 07 x 10"

0

0. 125

0. 207

0. 750

14, 000 BTU/lb

6. 05 x 10

1. 07 x 10'

3. 05 x 10

2.66 x 10

14

.14

13

13

6.8 x 10

2. 7 x 10'

16

16

1. 35 x 10

1. 24 x 1Ü1

16

8. 9 x 10

4. 0 x 10'

2. 3 x 10'

2. 2x10

li)

blunU il i oiu (12-dt'gri't.' uu liulnl ,mgli') model. Kinetic tcmpcratui'f!- arc seen to lall In lU pi 11 i til tur

low-energs inputs and 25 piTccnt for tngh-eiu'i'gs inputs m the e(|uihbruim-flow. calculations, I In si values

are high In about lä-2ü percent when thev are compared to more realistic nonecjuilibi mm i ale illations.

Some ol the latter were extrapolated din < tls from TKW Ml. I ..ihoralor us, using i ah illations applied 'o pro

totype flight londitions (see I'lguri1 Ü). Corresponding drops in loiuzation levels an given m Tables 1 and II.

15 -,

10 -

u o a

u

A Nitrogen n - 20 mho cm

O Argon a ^ 100 mho cm

12 "T-

16 -1

20

A (cm cm

Tgure 8. S|iort-( ircu ' Carrent Versus I.nutter An ., I'oi I wo Valm ~ DI I.HI I ti.i ,'..

Runs mad' m Argon Gas with äOOH li'lT lb l.m rg\, md Xitrogin M

12, DUO trnvib

H. Parameters Influencing Gi'iiei-ator ()utpiit

The detail) d theoretK al analyst s m.idi in Keleia I.I i .- 1 -1, .nd i ind m tin \ppendi\ ol this i i poi '

show a set ol parameters that gen ern tlu' output ol tin plasma giiH rator mdepi ndii.tr, md oi i iilli ■ t i ■. • 1 ■.

These mas be listed as follows:;

1. I .'mitt er Area - - (A ) i. diri ' tl'. pi oporlioml to tin tin rmieijn > ' as ion i ti n. tin 11 K i, . nl.-m. - i iii

Dushman formula

1 , (constant) A I exp th •■m \ k I

md hem e deter mini s tin magnitude ol short i in cit i urn nt output ai i onlmg to I . |iMt ion

J, Kmittcr to Cüllfi. tor Ar IM Hat 10 - - (/i =: A , A ) is proportiDiM 1 lo tin- r.itiu ol i . i.dDMi i li i ti on

i urii HI .it the emitter to th.it at tin- ( oll et'tor. In Kquation 1 tins p.i i\tmtti r .u t.s 11K1 > M >..-t.iiu I

i. I; nutter .ii id C oil re. tor Surfac e Temperat ires - - (T , I' ) elec t ron c nussioi, i • dm i 11\

[)ropoi tion.il to Hurface temperature at cording tc; tin- liuhardson- IXistim.ni ic|a.it ion .dnr. ■ . I i om I .i|,i..t ion (i,

one ( in note that T > > T for iiuninuim back emission, em r

K.i). Kinetic Temperature m 1'lasma -- (T ) is tin ■. ir\ soun i ol ll.i ^'i nei.itoi i m rt;\ I juations 2 1 , t.

.nd ! show, Ihe open t ircuit ■ ullage lo be direi tl\ proportional lo tin i lei iron ti mper.ituri ! iiaJ lo depend

log.i nthmicalls on the degree of lomzation m the pl.isma which is also a din i ! lunction DI I

1( IJ) Degree of lonr/ation - (n n ) determines tin powa r output di i c > 11 . tlirough t'e ti im -, I 1 .<|uation 2 I

,i i.d indn ii 11\ In neutralizing the sp.u e i ha r^e i real id l)\ the inns s ioi. e .i . t run i 1< ■ ;d .! t 'In i ithodi 11 is

proportional to the gas pressure and temperature.

■Id ). I 'lasma Resistance - - (r ) limits the effectu i length ol tin collet tor and i onsi ijuentl' has a

direct hi a ring on reduc ing the increased short circuit current output brought about bs an u« n a .^e u. '. i hicle

si/e, e. g. , \ em

5. Contact or Internal Resistance - - hither res ist. i in i is a - igmf u ant lonstituent 'o 'hi Iota 1

141 m rator mteinal impedance lor the plas ma jet si ale models. It oi i ui s pn ma r il\ at tin > olh i loi - lo- st i ng

contact point (see Figure 2a).

Ii. l-.iiultei' and Collector Material -- These go\(.'rii the output through tw o f.ictors tin ■.■..uk lunction,

v*. h n h in turn governs the elei t ron emission rate and undi'r proper conditions i an supplv as mm h i - 1. "> volts

t Ii rough 0 - 0 in 1 a]ua t ion 1. and the i lei tr ic.il propert us w hu h i'ont r ibute to the tot.il mti rr.al i mpedaiu e e i

Lit the generator. Bi'causi' the \.S1J is a low- ullage, high-i urn nt de\ u i , thi mteriial nnpi d.im e should bi

kept minimal.

It is ob\ lous th.i t there is a si ron g i nie rdi pi n de nee a in out; the \ a nous pa IM im le rs listi d abo-. i

1 or i \.impl ', a f.i \ or.ible effei I expei ted In a i hange n. one par.imetei might i aus« an ad\i rsi . Hi i t on

another. The following expen mental results show these \ anous effects, and «ill. the tin on I n ■. pn du I ions,

i an lead oiii to establish Optimum working i onditions tor the h\personii plasma generatoi ,

( . r'xperimental Results

11 u results report i d he i e wen i oil eel id dm mg a s'ea r m Sandia ( orpoi .■. t ion's 1 Ml kw pi a MIL i |el

I'n ihts . l-'inal expei i me iits are now under was m the 1 - mw f.n ilits with la rgi i model.'-, to ^tuds .i. u n at' i

detail tin i Hi i ts of parameters 1 and J.

1. K nutter Area - - Table III lists the various s i /es of emitters and col lei tors used. Tin i nntti r a

areas ■. a r\ between 0. H and 2. 50 m and /i sanes between 1 and Ü. D'i. \- pn du ted from l.i|u.it ion ä, the

short i ircuit i urrent shows a linear dependence ol I on the enutti r an a (l-'igure H) \i i oi ding to

la I nation 1, this linear dependenci should change a .s the p las ma resista in e bei omes sigml u ant i i ■ n I) I oh m) 1'

Ihis effect was not iced cli'arls n i in I rogen, but wa s uisignif uant m i rgon beca usi of the high de gni ut

i oni /at ion in tin latter. He i a use ol tin limited size of the jet and i onset ]ui nils ol the models, onl'. "t n nils"

wa re obtained m nitrogen gas represented bs the dotted lines in I',gun- f) The open-i in ut soltagi ^howi d no

di pi ndi in e on the eni it t e i ,i na as predicted from Kquat ion 2 I'igure > i omp.i r< s outputs I rom two ^i o-

im Ii ii alls similar models with different emitter areas

i' \iii.i. in

Modi-l Dimi'iiMuiis

I-.'mitter AMM Coll. i toi An

Uodfl (IM ) (in")

S-Ü 0. 85 f), B'l

.fiici 1. 7U 'J. 8J

u-o 1. 031 1 18» 1'vroK''P1""

Ü2

H2

r- iu S.i mi' 'J 95

S-lü 0. 70 4. !)5

S iO 0. 86 ü H4

2. 48 > 4 1

S-(J 1. ,i0 Ib. MI

6 -i

5 -

5 3-| u

i* a.

2 -

1 -

\

/

s- \

/

Legend \^

6 O S - 30° - 2 K

/ A S - 3Ü° -1 ^

/ A (2) A (1) - 2.50 0.90 \

Argon at 5000 n i .1.

// x

\

\

\

\

\"

\ ^ (2)

/

\ \

\ \

\ 1

— —T t^-

\

\

\

\

1 6 8

Current in amperes

i

10

\

\

\

-r-

12

r- 3

- 2

- 1

14

I igui-i 'i. ( (ntput t i'otn Cicoimt malls Suiul.i i' Mmli I > \A nti Diltri i nt I. niitti i \ i ■

J. Kmittcr to Collector Area Ratio - - A largi" number of runs were riiade l<i dfti-riiuiif the tffic t ol /<

on power output, especially on the short-cireuil current Figure H .shows this effeet graphic .ills In general,

the trend follows theoretical predictions, however, for most models the ilfnt ol flow separ.ition cner the

model aftirbodv, the contact resistance between sting and collector (see Kigure 2a), and tin plasm.i resist-

ance becoming effective for /) ^ 0. 2, could not be identified separateis ind, consequently, an effectisc /< - iV

vs.is used to correlate data. I'or negligible r and r , the data fit thi i urv( i 1 , - 1. J '" st 'ÜI'

"fitted" collector areas only. These were determined s isualls bs obsersing detachment and reatt.u hmi'nt

points and collector surface glow. For increasing plasma resistance (e. g. , air and nitrogen runs) the point;

I vs A curse fell below the respective /< lines, indicating the effect of r This point is disc ussed in sc em p

greater detail below, under 4(c).

i. Fmitter and Collector Surface Temperature -- These temperatures were measured with a two-

c olor pyrometer attached to a recording chart. When the arc jet glow osershadowed surfaci c olor tempera-

tures, tin |et w.is turned off instantaneously and the surface temperaturt estimated from the tum -tempi rature o

dec as history, with an accuracy within »100 C . Depending on the ,irc jet energy and model matt rial, average

s.ilues of T sailed between ',<UÜ and ^L'UO (.'. Stagnation point temperatures exceeded UOO ( on sharp em

cone models (Figure _c ). This temperature was deduced from obsersing melting tungsten. T was less than c

l-MJo'V for S-0 models (see Figure 2), about 1500 C for model S-ü surfaces, and lbüü0C for S- iü models.

Hu k e mission from the col lee tor becomes sign if u ...c for I I ' U. H. Maxi mum teste d c one- anyles were' b c em -

Figure 10 shows the output for lour geometries basing comparable' A iü0 w ith r /T < o. c eTll (1 • li)' I < I 1 1 t' V i • ( ) /

Il.i mtmrht .id gfonu't riey art- shown to re duct1 output bn ausc ol reduced ffft'ctiw (i ein.suit; from flov, scpa -

IM t ion. .A (1 • (i ) for S-.iO was twice that of S- 10 with a shghtU lowei output, [ji'obabh' bet a use ol i, onsider »■

,l)le ick emission from the S-,'iü and se-rs large ßdi ; 1. Ü).

■l(.i). Kinetic Temperature in Plasma -- Accurate estimates ol this parameter were diffu alt to make.

C .ilon me trie and pitot pressure- studies (Reference t.i) combined with spec trog rapluc estimates (Re ferenc e 7 )

gase- salues of 12, 000 K electron temperatures at the stagnation point ol the- ASF schule in 5000 Mil lb

argon g.is. lii air, stagnation temperatures were estimated at TäOÜ K lor 12,000 HTF/lb energs input

L'nfort un.i tels . no spec ! rographu results are- available at present to check this magnitude which mas be

somewhat optimistic . Figure 7 gives plots of T over an S-fi shape model for air, using both e-ejuilibrium

ind nonee|uilibrlum reac tion calculations The- maximum temperature drop from stagnation point to afterbods

is of the- order T. T ~ 0. 5. o

To estimate open-circuit voltage salues under optimum run conditions, which m argon would corre-

spond to V 1 ev, -; - 1/2U3, and in air V = 0. 7 t-s , -, 1/155, the following table is obtained:

t- m

(F<1. 2)

V ■ ( em

(Fei. :i)

TABLE I\'

Open-Circuit \'oltage

A i rgot

4 V (soils)

oc

0. 10 i. 42

0. 01 i. .(7

U. 10 (.. 51

Ü. 01 5. 1)5

\ll

4

0. 10

0. 01

0, 10

0. 01

V (volts) OC

1. 92

0. ».7

4. 22

2. 0.1

2 3

t 12

10 -

8 -

~ c 3 a

=2 4

Argon gas at 5000 BTL'/lb cn.ru: Legend

O Model S-6

G Model U-10

A Model S-30

v Model U-10

l-'lguiT 10. 1 'uwi i ( h.tput for \ ii i()U> Mi HII 1 (itcjini M n ■ ..' ( m.-' .:.' '• ' I :.• it;.

\li i MII i d '. ,1 lu< s in .i igon >!'. IIM tjcd .ibuul i. * volts with tin cxi. i[)tioii of ■■ \ aluc ul ■). -1 i ■. i )lt .i i i y. .-tf I ( d

with mud i 1 tip flush v. ith nozzle t'Xlt when- V might h.i\ f Ijccn ( ID.-I r to 1. i f. 11 f\ sl.ign.it lot. |jo;nt Ii- rn -

pci'.itui't .-. w i M in' i.suird ,it .i point 1 uu I, dow us t ream of nozzlf rxit 'A hi i <■ most ol ttn tc sts v. * i i r u, I

This uidn .itts th.it tin- cmittiT sheath \' was possiijU nt-gatui , \ notr ut i aution, howi \(i 1. j i.itions 2 i-tii

and * arc basi-d on thi' assutnption T is the sarrn at both iMiuttiT and (ulliitor lor I ■ 0. 7 I it is c t-i i m

possiljlt- to obta m 4 \ olts opi'ti-i ircmt \ oltagf w ith \' • U .uid 4 Ü. 1 sec XppincJix) C OITI >|jonding

nn asun mints in ,iii gave optimuni '.aluts ol 1. 'J to 2. i volts open i ua uit.

■lib) !)« uia i tit loni/ation -- From above values ul 1 , (Tables 1 and 11), the percent loniz.ition m the —& ,.1

y.is a round tin VS1' model i an be summed up, In sei t ion ■!(..) abov e values of -, were based on i omplete

ehargi la .t r.il i/i d flow londitions llus, however, w.is iiot tin i asi lot .ill test lunditions, as w.is evident

Irom spei i.il seeded gas tuns when values of V uu reasi d bv 1 > to 2') pen "nt, depending on era rgv in|)ut,

uid I bv .is nun Ii as 10U pel i ent (see Table \' below).

Gas

Argon

Nit rogen

T.AH 1.1. V

( hitput with and without Seeding

No M ill 1 ■' K ,( ( ), Added

l.nerg;,

:! 1 1 ^ lb 1__ V

Ul 1 SI

=), ÜÜU 1. '> 14. I) 1 ' 18. (J

4, ')(J() 2. ') 10. 0 n. o

14, 00Ü 1. In 1. o 1. 3: i 7. ä

1-', 000 1. 20 i. 0 1. 7 0 Ii. 4

I'w u t , pi s of .seed material wen used, KC 1 and K ( () . Be« ..use ol the elei tronegat iv e propc rtus of

KC i when \ -seeded gave 10 peri ent lower values than v' - no seid, the K( 1 was disi a rded. K ( ( ) oi oi 2 i

pow de r w ,.s led dow list lea ni ul the an at tin rate of 1 gm / mm, oi a maximum of 1 peia ent bv weight ol t In-

gas mass flow . The elfi i | ul ioni /at ion on short -1 i n tut i ur rent output is further illustrated in figures 11

i ml 1J wheia , in addition to sei dmg, spei nil runs are show n w h.u h w i re made w ith various ma ss rat los ol

A" ^ , K''^- I igui e 1 i, on tin other hand, eonipa res runs . n argon, a ir and nit r'ogen on the same model a nd

i ompa r abb ene rgv inputs, with maximum output decreasing from 1 i w atts to i watts, respei 11 v el v .

fu I, I'lasma Kesistame r -- Hefernng to Kuuation 4, the short-i ircuit i urrent is seen to depend ._ 1'

on tin plasma resistani e through the t« rm r II une assumes r to be represented bv

r I.'a

aH a

2 .

3 -

CO

o x 2 w u

0

100'? N,

A Run 1 K - 5000 it

O Run 2 K - 3000 ;'. 1 L'/lb

G Run 3 E - 5000 Hi I /ll.

A9

A- — "' 3 2 50';

-i 1

100'; Argon

CJ 71

10 12

i^u M 11. I )> i;ri i of 1 oi u /.it n m or i Sin )i t ( 11 i nl ( uii « nt ( Hit put.

\ ryun- N it fogcn Mi \t uci >

18 - Legend ^

A - Argon ' „„,,., / A-5000 + I'

:;K

K - Potassium (seed) /

N - Nitrogen j

All numbers are in HI I /lb '

16 -

14 -

1 A-5000 12 -

/ /

10 - / /

8 " / ^/ ^ r

6 - ^ N-i4ooo + r;K ^ N-12000 + r;.K

4 4 - ^•^ Air-12000

— -^^^ N-14000 ^\ N-12000 2 J

" N-Ö000 0 i il I i 1

10 13

10 14

10 15

10 16

10 17

No. of electrons cm

10 18

1 lUiu i- 1 J. Shu it ( 11 i at ( urifiit ■ > i ~u> l.li t tion 1 )iii.s it ■, ( I 'rii-i i ill i| (I i ^ I rum Spi i I i u~i up'. , Si i ill il I . : -

IMiig S.ih.i i qu.it ion )

14

12

10 -

^ 8

3 a

6 -

4 -

I /'

/

N

\

Legend

O Argon Gas at 5000 Ml I ,:.,RuiiIX-5

A Nitrogen Gas at 13000 li M .i , Hun IX-9

O Air at 13000 HIT 1h, Run 1X-H

Model type S-6

2 -

CurrL'nl in amperes

I IUUI I 'DM, tl ( >ii,|jv.l ,il.il \ - 1 Chi 1 M t. r.M h .- ci! (ic-1 in \i ^m,, Nit ID^il i ml \ II

I i ' I ■ m 11 t 1 I i ■ id 1 : i .^ I 1 [ 11 )

pi ,i> m.i i undui 11\ il \ mhos < m

c- so mi fr.u t ion less th in OIK , di'piiicJin^ on t r.i jit toi

I Kl.lt lOh 1 1 .ill 1)1 I'l \A Ilttl'I!

( i /n ■ <S i

(71

irh si i i. Hi,it loi .i ^IM i /< 'AM Ml ü 1(1 "'•-,■ K'| ..itioiis ') .iMi T .ii-f plut'id ii. 1 i^iiri' 11. It is

'In short i i re uit i ni'int t'iills below tin i 0 (of a • ' ) v .ilm il pl.i sm.i n s ist.i m i is nu I udi (i I'ln 1'

- i r s'.i nt n s i St. i in c i ui'. i s show ,1 1. t;iii t ii .in! i i i In i t ion in short i -i u . I i u r r"i nt lor .i t! r. in ; ( h hn ' a

s :■..! II Ii in .i lou. pl.is m.i i onduc 11 wt\ or large I i h i I ron 11 ,i jn t oi'\ ' c K ) is usi-lcss . i s sin. Iroti. i i, i ■. i

( 111 lot",. 1 1 .)') l hi i ur'. i-s in 1 i tj'.iri 1 -1 1 n- ,ihou' ) pi ri i i.l In low. i !,i .. 1 2 'M i iii'\ i s lion.

>i . ' ions -lUi ) and 4l I)) (7 n ,i rgon w.i s i st ; iM.iti d .is 1 ()t) Miho i in .nil i., .i ir .is JO irho i in I m ■ 1 U i m

• lln tr.c rlii Iron lr.i|fi tors this i oi n spomls to : Ü ! ohm .md D -1 ohm, ii spc i '.-.i \\ II om i omp.iri s 1'

I he i output . ii .i r"t.'i ii, .md in .i. I' tor .i t,'. . in /( .i ml Ii i i .i: r" o:.) • J i (.MI) I'h IS dilti n m I . S In 1 n . I I| SI si si

' u result p.i I l i.i 1 h. Iron, rtdiu t-d tin r in ion u c m i ss ion in .i ir .is i omp.i n d lo .i ryon In i .. usi o| poss i hh l.o k

ol i haryc nt UIIMI izat ion in 'In former (loni/.al ion m argon is a lai tm ol id gre.iti r than .n air), and p..r'i.ilh.

hi l .iU.SI ol I f-OI iXallipll for H 1 i m (i (I J I (aiijon) J(l all) (7 100 (7 JO ', 1 0 p II 111 \ all I

0 7 then ( ( 0 Jli \ m w si ' ol e.\pi I inienls pn si l.ll\ undi I v«..e. m the S.u.dia I'lasma 1 argon an

i .i hi ira tor'. 1 Inw 1 ai 1111 \ with model s i /es 2 • o 10 11 mi s 1OI,I;I I than 'hose usi d in I la 1 Ml k v«. I .n 111 s will

i i..i hi e us to de'er mine this et lei ' with u I • at i r .u i in u ■. I sei In low ) -i". i i .i 1 runs will. . nsul.it or li ngt I.t-

■. . i r ■. i n g h e t w i i 11 0 J t o J 0 11 ii 11 c s i n ,1 r g o 11 i n 1111 .11 e d n o s i g 1111 11 .11, t i h. 111g e s 11 i M i (p 111 11. i..' i , i f ■ i.

i a, t he ot hei' ha ml. then w.is ol.si i '. i d ,. 1 'i pet i i nt ri dm t inn i n i <A hi n nsu hi 11 u h i.gt 1 A ,. , m i , ,i ^i d I i ,.:

0 J.'i IIH h to 1 ') im lies loi' a I ixi d ( on'.u t ra si.- tm, i i

'). l ont.u t Kesistaiu i \ hi rgi i ■ ist.nu • , i , v\ .is n.t rodiu i d I rom tl it.n I pomi s In 1« i i n

. mi He r .i nd tin [in k- uf) rod and helvM i n Ha i olh , tm i ml I la st, m.' \\ l.n 1, s appi uied 1 hi model .. nd si rv i d . -

tin i on ma tor In i i .i r i'\ mg i urri nt I o • xt i rn.i 1 lo-oi. I la --i \ .i 1m > A i n mini im /i d le, using i .i dim um soldi i ,

Aim h iTielted upon he.it mg and madi .i Inpi id i ont.u I, , u , ir-llg-liiUi)uidmil.il.illo\ ,1 tin tw o i onlm t

points. Miiumum '.alues ol i *i n 'it <>ii|i r 0. 1 ohm and olti n is high as 0. i ohm. \l.i •. i ilium pow.. i output

gi m rails ot i, uried .it i 0. J ohm, mdu at mg .i possihh i • i 0. J ohm nidi I i nml.l mim ol ojit i miiin

mli i n.i 1 i mpied.im i i ontiol. Mm h mm i nl lahle s .i Im s a n 11 irllu onimg m t hi l.irgi si .i h - modi 1 tests no«

nidi r w , i ■. in tin 1 m A In ilits

I =I/Ith

c : 7 J

/ c

\l.itfi i.c Is - - r.iblr \ 1 Uäts thi' t\ pi of materials used ub iimi ti is, uihulaturs, .md lollcclors

I, iiuttrr

\l ,1 ^IMphltc

1 '•, rolil u lir.iphitf

I 'iicnol u i.i rbon

' I' u n y s 11 ■ 11

T.i nlaluni

/.i ri unui m- IM rinde

gr.iphitc, cutcctK

TAHl.l-: VI

Model Materials

C'olk'c tof

AIM yraplntf

I 's rollt ic graphiti

1 'Iicnol u i a r'bon

Tungsten

Tantalum

Niobium

Mols bdcnuni

(h - 10. U -2. ."3, /.r

Ta - 10 V\

Mo - 0. ,'), Ti - I). ÜH, /r

InMil.itor

Horon nit ride

Al,c) '.)•).<;■ •j'). ö"

UMI 78:)<

\1 () ' a v olurut

percent Mo

\ 1 ^ ) • i volume

pen ent V\

A special poiHJus uisul.itor developed In M.itti 11' Mernoi lal lnstitut(

('olumbus, ( )liu).

The rundami ntal > h.iractenst ICH i-e(|uired ui emitter and i olleclor materials .ire: ^eiier.il therm.il

i i M.-'taiu e and mechanicil integrity, good elei trleal cundui t is it\ .ind luv. tliermIOHK w. ork liuu t ions. < )| tin si

tlit'i i , experiments showed tin last two to be the least import.int bei .iu.se littli i ould be done to preser\i

- .i I.ice mtegnts in the highls reactive atniüsphere of a dissoi i.ited-ionized air. Must leir.u torv metals

tormed high resist.uu c oxide 1 i\crs on the collector .md lost powi r output utter 1 ü se( onds ot run tune,

11.is w, s not the eise with S-iU models with 1!)()()-JOOO (.' surlace temperatures nheri oxides he! mie

•. ohit ile. I 'In noli i impregnated with gr.iphite had higher i li c tin resistuiu e than puf graphite and ga \ e

71) pi n ent ol the out|)Ul obta ined 1 rom graphite models (see "l )pt i mum Kesult s" below ). I'In bi st output was

ol.t.imed m a graphite (i until r) - T/.M (collei tor) model primarils bet ausi ol good i ollei lor-lo-stmg i ontai t

and '. nlat ile oxidi s. ! 'vrolit n graphite emitters produced a uiulorm em iss ion I nil the a - direct ion i ondiu t r. it \

Oil'i I ■ d nsisla III i a- high as phenol 11 i a liloll.

Tin msulatoi s w i n chosen pr imarils for good I her mal shot k [JIOUI rl u s. i )l tin si li Ml - 7 Hü ranki d

best, followed bs boron iiiti'idi .md \1 () ' i percent, molybdenum dispersion Fhe porous natun ol tin

1 1 rst ma fit 11 dil I li ult to kei p i lose mi i I la mi a I tolerances and hence tin last two wi n usi d most e\ti nsi\ el\ ,

i l, i ipt imum Results

(i i)

I )ata redui. t ion showed blunted com emitters (Ü. 2.)- imh emittei r'adius) lollow ed In e -1(1 coim al

illerbods, /< ' U. 1 ä, .md graph Hi or tungsten surfaces to ;. le Id the highest output (Figures 1 ä ..nd I u ),

I igures 1 ä - 1 H i'epresent sa mples of outputs gi-aplm ally. Tin solid lines n i ui'M fits using 1 a|uat ion 1 with

li 0.1. -, (argon) 1 J'U, -, (.ui) - 1 la:') and i ü. üßtol.ü.

4.0 -i r 16

3.0 -

o 2.0

1.0 -

I (amperes)

Figure 15. Output Data for ß = 0. 15, Vj = 1 ev, i = 0. 1 from S-6 Tungsten Mode; in Argon at 5000 BTU/11J

Legend

O Graphite - Tantalum, Run IX-2

A Phenolie Cartoon - TZM, Run IX-4

Model U-10 O Graphite - Graphite, Run VIII-4

Model S-0

\ Model S-0 0 Graphite - PG, Run VIII-8

* Argon Gas

7500 UTU/lb

5000 BTU/lb

5000 UTU/lb

I (amperes)

l-'i^urc Ui. I'owcr I.CVCIH from Various Models Showing the Kffect of Argon Gas Knergy on (>utput

:n

@- ß 0 2'

b)- /i = 0 1

©- ß - 0.15 curve fit 5 = 0.05

(d)- ß r 0.15

curve fit S =- 0. 10

0- /i - 0. 1. 5 = 2.0 Theory

E Jet energy 3300 H ru/lb

Jet energy 6000 Ml r/lb

0.25 1.0

I I . (dimensionless) th

I'lguic 17. Volt.i^t - C m ii nt ( 1M i ,i( ti iistK s for Vy 1. U,

\'.ir'ioub /< irul <5 Viilui's m Xi^on (i.is

Legend

0 Graphite - Graphite, Run VII-2

A PG - Graphite, Run VII-3

Argon at 5200 UTU/lb

Model S-0

r 3.0

2.0

o >

- 1,0

% 4-

l^ c

2 -

Legend

0 Graphite - Graphite, Hun V-2

A Graphite - PG, Run V-3

Argon at 3100 iriU, Jb

Model S-0

/

/

/

/

/ \

\

^v

\

\

I \

1 I (amperes)

(b)

\

10

I'lguif Ui. 1.11 IT t ol ( onl.ii t Kcsi.st.iiu i betwein I '\ tollt u (Ir.iphitc Shell md

C'.irbon SubstiMte on ( )utpLit

< I

iii.iti tin in.Min.u.i powii nutput uf tlii.-- L;I in r.itur tin rxun H.~IOII r 1 (I - i h ' ' h ' Hi t-

1: \ • iH

th

, > ii i.i \ im i /i-d (MI Kilr niu I 1 ) .md plotti'd .is .i tuiu t ion ä {thcrmiürm to IM lukirn clcit roil r;i tio) for vanuub

ihn of li .iiul i" (or r ) m l-'igun.' IU. I'or plusiiui clcnsitiis iiieoantori'd in .i plasma jrt i ~ 0. 1. Ihr rtlVit

■ '1 i on li is bi'i'ii to UHTIMSI' .is j-i dci. I'IM si s (or as tlir ( ollii tor si/r inniMsis). (Soc al.so l-'igurc 1-1. ) i'

(ti.ii lyain tin rr is not cnoußh rcliabU' data for r to allow a direct i xni-rimcnt.il check of l-itnin l!) The P

ti ■ i.il.-, howi \ii , are m the expec ted direction as observed in Figures 1 i- I'.', and espec i.ilis m I- igun 18

Ala n (( is an "cffei tue" valji , taking into account r and r . p c

MaMmum short-circuit i urrent measured was 2-1 .imps o\,er a hemisphern emitter K i 8" .it .iJäO K

\i i ordmg to the Ku hardson- Dushnian eijuation

1 . - f'A T exp(-e0 /kT ) th em e em

tlii> should ■. uld 1 . Tlifort' - 120. However, if one assunu'S T to be a function ol 9, tin .i/imuthal 111 em

..null . and assumes a parabolic temperature drop from stagnation point H II to 9 TI/2 or j

1' .!2ä0 - 2ÜÜ 9"" tin above equation vieids CM,

1 , - 240 -H | T (91 exp th / em ' kT (9)

em

sin 9d9

or I , 27 amps. i'.ihli \'ll summarises the optimum output per emitter area with M \i r.il düfen nt mati th ' iii

rials both m argon and m air.

IAIU.I: VII

()l)timum Output per l.nuttei Area

Mode:

S-(i

( 12U blunted c one) [i ■ 0. 15

Material

(, raplute

(emitter, collector)

I 'henolic c a rbon

e nutter, graphite

collie tor

Argon (a, UÜO MT! ^lb) Maximum

Si Ol

'ow 11

amp, m" . olts w ittS; 111

2 1 i. 2ä 1 J

15 1.2f.

\ir (12. DIKI M II Ih)

M \ | 'llW I 1

imp ill i. olt s w.tt-- in

•I. (I 1. i 2 1

< 0 1. Ü 1. ri

S-.iO

IIIU' shapi

li 1 2

Tungsten

(emitter, i ollector)

I 'In nol ii

iarbon

(i nutter, i ollector )

2 1 t. U ■I a

i (I 1.1 1. -1

M

u

max

TO C

7

I ^ '' ' h i:lL;,- lit oln IDU^ from 'l.ilili \ 11. 1 . i M [iln ni.)l n i rlu":, i> .--i i n ID ■ \ i l, 141 . IJI 1 it 7ll |i( 1 1 1 lit

1 'I ! Li -ImM 1 j 1 1 ,1.1 . 111 1 1 lit ul til ,i[)lii!i ,ii,(l ii II pi n 1 1.1 i| tin pi n1.1 r 11 it|uit ■•. it I, no .•- ILll.il 11 .1 ut . K iin.'' ill

■ 'p' 1. ■ 1 . i ' ill . 11.' fit . I'In ! DI nil 1 t'A i) >liii^ MM 1 I ft I ol in, 1 1 iiipi il.iiu 1 olfi 1 i il hs tin in iti 11.11 .mil tin

. ■'' ■ 1 jui.iil ~ 'n tin t .n t t kit V 1I1 pi ■ lid^i [H im 1 11 s on tl.i' pi.i - m . 1 m 1 t;\ . >ri oml. 1 omp.i nun tin ~- 'i -11.1 pi

A ill, ;i ■ u. 1 tot in s- 10 ^h.irp 1 uiii 'iioili ! ii. ith /( 1, ;i .- . ,.~\ in M 1 ho v. .1 l.i in 1 i nlh 1 tui-to-1 imtti f

1 11 1 1 it 10 (■- m 111 /' ) 1 fl'ii I > output ill tin 1 -i ol 11^ oil. I low 1 \ 1 f, tlii> r.it 10 l> 11101 ( t h.m 1 ompi I..~.I 11 il ! 01

n. MI in i ..UM ol 1 onsuif r.ibh Kmi 1 pi .-m 1 1 ondiu li. its ol tin i.itti 1 .

t

1 l.i I. inl.i >! --holt r 1 M mt ■ 1.1 1 1 nt 1 1 1 01 1I11I t o il.iti m 11 nm. '■"• ir- Jl) .1 nip.-. 1 n" ol i- mit ti I 111 .1 .md tin >

hinlii1.--! opi i.-i 11 1 uit \ olt.in1,. 1. I '. oils. In .1 U', tin sc \ .1 Im ^ w 1 11 fi .1 nip in ■ ml J . i . 1 ill -. n .-pi c 11\ tl\ ,

Id pi it liu 1 it'. o| 1 m.-- lot .dii.t n .11 m mli 1.- « 1 re yo\ 1 tin il i Iml Is bs itl 1.1I11I it s ol 1 onsi i ul is 1 1 .n.- 111 tin

p l.i ■ 111.1 11 t ., 1 ul 1 1 pi 1 t.ibiht s ol 1 ont.n t IIM.-.! 1111 i . Iiuli r in - 1 i 1 n.ilii um.- ol i on' lol 1 c pi it.ilnl it s s .11 n il

In t vs 1 1 n 1 U 1 ml J 1 pc rtcnt. \\ In n i ont.u t M - ..-tn m i- .s .1 > m.cli 1 , h IM 1 onl lol. loss 1 ic |i t 1 1 11.1 lul it s A 1 -

1 .MIM il piim.ii 11-. hs 1 li 1 troili 1 i-osion.

1- 1 11 !■ hnht ( onihtioiis

It 1- ililln ill to U.SM ss the ix.n t iMiini ol .ippln .ihilils ol pl.iMii.i |i-l 1 \pi Mminti- to fri 1 Ihnht . ondi-

t ion.- -A In 1 1 tin ol i> slnx k ioni/id .md h,i s ( omp.u-.il is t Is loss 1 1 knu t n tt mpi r.it u 11 .s Ih.m those I ound in .1 n

iii jit. I 1 L'UI . _' 11 i> ,. plot of ili'i t ion 11 mpi 1 .11 u t 1 .- .1 i.d di L' 1 ■ 1 . il n m. /.11 101. o > 1 1 .1 1 - im h di.i nn li 1 blunt

I n-m 1.-pin 1 . 1 s 1 imlr r un .1 n - cntrs tl'ajfi tors ss itli J J , -i.')? ft MI I I - I nt r S , 1 hn it s . Iti-tss n 11 .1 It it udi s ol

J fjd tu 1 'Hi k 1 lol 1 it . pin nol ii 1 .1 ih on 1 mitt 1 I 1 .111 i)i m.idi to \ n Id .1 111,1 \i ni'im ol 1 .'i() .1 mp.-i sliorl 1. 11 1 ml

1 ir 1 1 nt ss ith -!. 0 '. olt - opi n -1 11 i 11 it s ult.ini ( 7 .') w.itt s) bs dl I11 t Is -1 .11 my - ii[i the [d.i.- m.i |i t d.i t.i obt.i 1 m il in

,1 ir. \i 1 orduiLI 'o 1- if^urc J 1, howrs rr, rln t ron 1 1 uidiu t r. it n -- m tin hound.i rs In s < 1 .111 not . xjnc li d to

1 \i 1 1 d 1 (HI mho 1 m. Ihi pln.sm.i i-rsihtniK 1 us 1 1 m i Hoc t is 1 1 lit I ron pn lb ol ) 11:1 In .- vs ill tin r, in it li n.-t

0. 1 ohm, re dm inn tin s 1 hu b output to JO ss .itt.--. i'tus ss ill rfi|ui 1 1 1111 rin s mn t In ■. 011., |M output to di 1 S I

tin In mi tin 1 in nn n 1 111 1 1 nt -■ hs 1 illn r dr. idinn liu surl.u 1 into M s i in i 1 mittir -1 olb 1 toi p,i n's 01 .IMIIL:

-upi r.-.. 1. .1 it. 1 1 -1 nt rs .-pi 1 d-- c m-i'''l mn ''" ' " '■ 1 ill.-- , .jn n-1 1 i-i ml ■. 11lt.11:' . I illii 1 ol tin .-1 nn thod.- ss ill

1 .,u.-i tin output ol . lull - M/. 1 1-1 nils s 1 Im li ( (. U - ft dm nn ti r) to In 1 kss 01 inon . ii. 1 ...IM ol hinh n -

, onibin.i1 mi. lit - . no out] ml 1.- 1 \pi 1 li d In loss ill 1 Mill 11 . I 1 it it udi unh M-, .-on n 101 m 1.1 -1 1 dmn 1.- u-i d

t rom 1 In 1.1 i.-i 1 oin f u ft In r n 101 c, Innh pri ssu 1 1 1 1 . 1 tin .-il nnnn t ion point is o \pi 1 ted ti 1 inh ,hil t In r m 101, H

fimssioi. hs 1 t n 'HI ,\ H 1-» - nn .m in 1 pnth .1! 1 mitti 1 A.IU)

I utun W oik

si inn ol tin 1 1 Milt.- r. port, d In r 1 ,1 n nut s id I inn 1. \ M t ol phis nm ti -I.- m 1 1 , r).'| r ' -' J 1 - 1 m 1

dm nn 11 r) 11 1 .im 1 xpi - tid to s u Id mori nlmbli n .suits on tin 1 omhincd 1 Hi 1 t s ol 1111 n .1- inn ' olb 1 lor mid

1 mitti 1 ..11 1- .ml tin n bs li nntln nmn nsi rn^i 1 Im Iron pnth.- from cmittti to 1 olli 1 toi hut -till lioldinn 1 s>ii-

t .n t n .- i.-l 11,1 1 ton in mi iiium. l-'rom 11 1 nils obt ,1 mod to dntr it is cxpti ted thnl nu rcn scd s ,1 lues ol r will

s loss Is din n 1-1 I In 1 , s 1 r.-u.- A turs is ( l'inu n H). th 1

lO1^

10 15 J

10 14

C 10 >. w c n -a c

13 I

10 12 J

y.

10 n

10 10

io9 -'ic"5

r 38

300 250 200 150

Altitude in kilofcct

Kigun -0. l\l(itic)M l>'nsit> .inci Kinetic Ti'mperaturc Near Stagnation I'umt fur Blunt Ke-entrv \'fhule .it Various Mtitudes

i7

p - atmosphere di'nsitv o }

Temperature, K x 10

"i(4uri' ~\. K li(tri<al Cntuiurtivit s as a l-'uiutmn DI T. nun ral nrr

T ilui lilji'uiMi An- at V'ai'ious Dciihitirs (I qiatinn H-'i)

CI

Si vcr.il runs will also be made witli ir.sium impri'giiatfd tungöten ciiiittcra to smiul.iti' in-flight

Heeding i ciiulitions, .ind a new ael of he.it resistant carbide surfaces will \>r tested. I'inalh, models havi

been designed with two emitter-colleetor pairs to evaluate the "in-sern.s" beha\ lor of such a generator.

These results «ill be given in a separate report before the end ('■( the \e,ir.

('i.-lO

AiM'i: M)i.\

Tli IT i .UMU 1 H.II points uill be discussed bi'ii-fls m th.s Xppi'iidix: tin slu-.itli pott-nt lalh .it tlif r mitt IT

,I .'ul . ollii im , ihr i 111 i t of 11 ml i ■ ht-.it 111^ and Thump son cml in tin- pl.isnui ycntTat I'd l)\ thr l.i r^i' < u i i • nt s

du MI pi 11 i ul i) it from i" iittnl ilt rt runs, .u I high din.sit \ pl.ism.i SIHNIIIIS u ith masts v rloi it\.

\. Noti on V and ;' i m i

11, H' !i nrn r 1 , I't | u.i t ion i for tlir current flow .it the mutt er is wntti n as

I - I i'xp I - ,- . - "-' 1 Mi lii'tMl i\ i V I /ii i > pl.iMii.i iviti nt ul I ( \ - 1 ) Hi lfm i'cm " \ »< l . / ! ni

i nd

1 Ith,.xp kT

I fur posit iv c V rein nil

l \-2)

j-'i'om I j|u.it ion \ - 1, sol vintj foi \-

c in !

k r In

•1 - I Hi ifin

k 1 } /,

J , > .1 In ifin

- .1 f J.-r

(A- 0

Siiml.i nls .it tin- i olU'rtor. foi \'

kT -'- tu

.1 t- J 1 2irm ir ' c

( \-l)

Takiiiy iiiln .M i ount tin n sistivc drop in the cell, tin ml \olt.i^i ol the generator beeomes

V - - V • \- • 0 - ^ - IK i in c i' e A-5)

11

;• .■ , li .ii Iroir, this 11 jvi.il mn tli.it lor y) - 0 0, tin b.iii H i puti nti.iltj .it tin i .ithodt .md ihf .uioili' .iM ol

L' i ■ t i nip or t .u n. c, 1 ookmy ;it 1 >iuat ions A- ii and A- 4 iibovc, it bei onics ob\ IOUS that fur 'I" ■ I' V

A .1 ili . i i .i.si- it liMSt pi opurt lon.ilU to .i dec rr.isc m T . Ai. tu.illv, tlic dii riMSi- in \' is proportional to

i ,':,:. I or .1 l) for i-x.implc, T - 9Ü00ÜK (T - 1 ii, ü0üOK.) m aruun, \' C.JOOO) =; 0. 57 \,' (12,000). . _' i J id rZ c i

i IM --liowld al.io :ioti that .1 is in i/tni'r il larger than .! l)v a fai tor proportional to Lollittur-to-cmitlcr icm U'

i tn. 1 /<

1 In ii|uivalcnt i \pi is.sion to l.iiuation 1, with '1' , > T is r 1 r J

V V /..

1

lj -)/4 - t

JL/I1 12- i ♦ -,, i - i

1 /i l< f i

• 0 - 0 - 1H (A-fi)

.■.in M 1 I' ' , . and suh.M iipt 1 arid J. refer to plasma eondltions at enuUiT and c olleetur i espi i tivi-lv. i i 1 i J

li, I la i moeleetru Lffei ts m a Joule-lie.aid Plasma

\. K'-nn ( Hi terenre Ö) and 1.. S. Hall (lU'fi'renee U) ha ve analyzi'd the thermoi'lei trie effeets in fully

HIM/I d joule heated plasmas. It is a straightforward method to extend the analysis to the t .is« of partially

mi.i/i d gases. \ssume n = n = n and n neutrals. Negleetmg inertia terms the eiiuation ol motion for l e a

■ li > t rons, ,ic c ording to Cowling (Reference 10), leads to,

0 - V p - ne 1, - nm v i <\ • \ (1 ' n/n ))T e I i ale

(li-1)

i nd tor ions

dv1

(1 - f)p~ - -rpi • ne

1

(M-2)

v. here

f 1 • n n

I - ne\ , i ne\ J i i

\ the velocity of tin mass as a wlioli

T time between successive lullisions

llu rest of the notation is conventional,

1J

\(i(lin^ l.i|u.it loius H-l aiicl H-J,

in ,

IVP = — J - J 1

r m m

UT ^ l' T i

substituting for i in tho electron cciuation, yields

ni'h •■

m

t1

111 111

C T Jl'T

vp

1 III

in J( T <- i T

IT in m

r T £vr i' 1

(H-3)

Di in in <■ 1 l.'iiu.ition li- i siinplilu't) to

iu'1. ' VV J (' (' T

in--i)

From lien on wc follow HNIHI (lU'fcri'nci' H) and write the i in rent ,ind CIILT^S cquatioiis for om1 dmu nsional

inol ion

ai: f \>a dO

dx

Q - c aöi; - dcrH dQ

dx (15-5)

cH,) ,, 5 do d^ " -J1'' 2Jd^

k'r wlu'i'c M — and thr nst of the terms are identical to tliobi of Urt< i im« 8, es., ipt lor tlic 'dditioii.il ti i in

on the ri^ht ot tin third ('((uation. Intr^rating thus i'(|uation and setting 0 / ,. d." \ dH

0,0 H ( i. - 1 - dx / dx

g = - j(0 ' 9 v< - fö)

j(-l - f0)

Substituting these values in the lirst two etjuationa of li-fi and mtrodueing tin- new variable n ii/, H , 111

following equation is obtained

dO c - (n - f) 9 ' r,(r, - f) - [CF, ♦ b(-) - f)| * d dn (M-o)

l I

I -iii.il ..in II- d ill III i > I. ih lh.it ul K\ IUI unls • tin .iilüitlori.t I ' niiM.inl 1 > J. 1 In ■ nl'it mn - .1 llu.-

i i|i..it inn i,- L; r, i n ,i > ,, i HI. i ill .iturr m Hi'ft'rciK'i'S !i .i ..il '' v^ lure tin Ih' i moi in ! i . i it lei t> .i fi >liow n 111 skc ■A

HI i .■ i I 1 nil tin 1) ii I 11 i:ir il 1 M I il nit 1 nil 11 A". , i i d> Ihc i .itllmli . I .fvs l^ .mil Hill/ ( Id I m m i 1 1 ) i , i i i ul 111 I In )

n u i i . -i m i In t inn ti nipi i.it iiri- li\ limit In ,it m^ .i nd Ini ,'i0 , nip i m i ur l'i nl 11 \ r 1> , II. Oh in in 1 It; ii' i I rm. n n J

pii - ■- 11 i .-■ .nul iOOO K inn i.il liinpii'il inc. nlil.i m n v.iluc ol 1 - lU)OI) K t''nr i .■ nip i m ein nm it r red m

I In pi i -i lit XSl' ^I'llf r.itor>, tin n M1 nl t IHM i- m itlci (In I i mi ti ii ipi1 r..t ill i - i ~ nnt ninl i tll.ili .i 11 iA Imndl i d

di t;ii i -, ind Im .in \cl pi.ism,i tcmpfiMUircs, V 12, OOO K, it is m ^lii;;li.i .md n tu.ill\ i.- i i nmi.'l l.i^i d

li\ i nl 1 is ions with t Im I't.iTgi't li pl.i s m.i i In I ; nns,

( . Iliyh IK-n.sits rl.ism.i ^hmths A ith M.iss Motion

\\ ,lli jj.is dmsitu's ..p tn I). 1 .d innsphcn , m utr.il y.is .ilnins nu m !i ■ i p dlis A ■ • U, (U nmilrl l)nd\

dl im ns ion) .md m.iss \ i-loi ItlfH v ft 1T), 000 tt / Si'f, it is i mpi i ,il i\ i Ini nm tn t.iki i nun i i .i t i I ill look it tin

pi ! s in i in ir iffs .i ml inn .i iri\ .i 1 rates \>. n h nu n n snl ni.i ss '. i Im it H s . . ■ . ■ I t In rln I nnh s (\ . ■ : )

11, i nl , Is innlrss [d.i s i n.is , .■ n lint l.i 1 \ rloi it \ nl' fi 1)1 t -n m till' ions ( sn l(i 11 rclni 1 , I.' I'.i.il i m i I i - 1 II A 111

musi . J j pi-1 nut t t dm t .nn m rln t ron i in iss ion. ! hm, r\ r r, in dill us ion ■ mil I'ollnl jil.ism.i ^ . sin h .i d 11 i i I

r.-t 1 tn.iti is dill U'LI It tn in.ikc .md .ill entire Is dll'fi rent .ippruaell Is nen-ssi I . I »ills .i ^i nel .i I nut 1 im will In

L;r.i n In ii , with details left for n luture work.

i'he ^ns e rnin^ equ.it ions nl mnl ion lor I on u ml elei I ron dil I us ion ill .■ ^11 tlhl 1 s mm /i d p. s nl knnA n I U ■ A

i li.i r.u ti i ist us ,i re

q • V " ' V ■ I =0 i i

q • V n • 7 • | = 0 V V

where

I - I) v " " e/./i n Vd l ii i i

I) V n ' 'l' " VO

((II

i nd 1 'OISSOII' s equ.i t ion

V 0 - In (/.n - n ) (; J)

where 1) - diffusion i oel'lielent, >/ - inoliilils , 0 poll nli.il

i I

i Um in^i tin Miil.i' M MI> i>l I .1 mil ( H' 11 n :.' i 12 ), thchc tlnii cciu.it lon.s i ,ai hi nurulimi'iiMDM.il i /i-d In

N II 1.1

c~ V~^ N - N

H( V • T \ ) • v ■ "; = II i i

u - n

< i) 1(1 \ • V \ ) ' V

will 1 •

I I ; * -;— N n , n , »' - i ^ k I

I ) /.I i.i i.i i i

c : h I . h I )i In i li nctli

111 i .m.il VMS [> t lun ili\ idnl into t wu I't ^lon.s. Ihr .i inlnpol.i i" it iff us ion i it; ion , i nd the slu .illi i i t;n HI

.>. ith rn.it i hint; liuund.i is i undit ions .it tin i nt erf. in-. Tin1 shciith solut ion It'.ids tu tin- third order iioni i IHM r

iil.'.il um

1 2 (I , , . i\i< d ü 1 dv

"1 ^ ■ "i^ ,2 * 2 dt dt dt

.Ml • « )t - I 1 • < ) A (( -1)

w In i i I i.s shcith i iiunliii.it i , pi opiii I lon.i 1 to the nonn.il i oordin.itc to the suif.u i , and X -- (n ■ V* ) 1 yK

is drli rnuni'd tiuni tin diffusion solution.

I IM I I . < 1, Kqu.ilion ( -1 simplifies to | i

OV''

.11 ((-:.)

• u 1111 . 1 111 111 n 111 d. 11' s . . i n d 11 i. 11;

.1 i,'

dt

I IM..) 111

1 .

A : . : . I ' i.' i . -• i 1 'IM ' UKI ol Ihr polcnl 1.1 i disl nbul ion in tin N In .111, 1I1 t c-| mini cl t ID 111 I nl 1 I.K 11011 (1 ol 1 ih ion)

IH-'UI 1 ' ll, 1II1 il 1 li-i Iront) .ind llu iil.isin.i 1 UM Iroiih

\ dt / o th

du I' ■ ' I \ t

1 / < A \ 1 . 'i , I '111.1t 11.1; iiolcnl 1.11, 1) <.' Ü, I rom 1.1iu.1l 1011 ( - 1 .md 1 J one 1 .111 show lh.il I , t' '■ i , i>i , Ihc ion

1 -1 1 \ -4 1 '

ii 1 1 'it .1; .il 1 OHM 'i unit 1 \ d 1 1 I ion c n w s.s ion is icdiui (I l)\ .1 l.u tor 1 >! the Knudscn nu mhi r .it tin vs .111 \ nioic

1 c 1 is' 1 s 1' u.it mil l< .1 \S1' would In 1 o 1 1 in ~ 1 I|I r .1 1 nl 1 is u 11, doni 11. 1 Ii il 1 mlnpul.i 1 i'i 1^ 101. .1 ml .1 I 1 1 1 1,111 sin .ith

1 1 1; ,01, with 110111111,11 '. i omlit ion (,1 ) ripl.u nl In

'L0. dt

I 1 • 111 \ <7t) \. ■xpivi) { \ ' iti \ 1.1 i) } , 6 1

tl\ srs .ilon^ Ihi.'Sr lines ,1 IT prrsrntls undi-i v. .1 \ . .1 nd icsull s w 1II In loi'lhi mn ir,^ 1 n .1 si p.i iMt 1 11 pol I

.IST OK RKFKHKN'CKS

I\)m\.ui, K. ,1. , The i ivpiTSonu- l'lasni.i C'onvii'ttT: I, M - •l!tij()( H H), S.UKJI.I I alior.itois, \ll)ui|ii('ri|iic, ,I.iiiu.ir\ 1964.

roui'.-iii, K, .1., \ llvprrsonic l'lasma l'owcr GiTifiatüi, MAX, 1st Annu.il Mct-tinj;, U .ishuiffton, I). (', , preprint ()-)-44'1, June 11)(!-1.

Us.itt, U. ,1. , Ui mstc in, (1. f.'. , Hypcrsonu Plasma Fhcrnronu Gfnorator, l'nui i-Mt\ ol Niv«, Mc.Mco Tech. Report l-.K- 108, Jutu- ÜHi-l.

\\ is mouth, .1. I-'. . "1 .li i 11 u ,! 1 l.'iurgy l-'iom iligh-TrrnpiTaturf Plasmas," ,1, I.. 1.. .luurnal, pp. 1HÜ- Ui i, \uf,nisl 1962.

Lewis, II. \\., and Hntz, .1. K. , "Kffuufics of thi- l'lasma ThiTmocoupk'," J. Appl. Plus. Vol. il, N'o. 1, \pril IHM).

(i. I.uhii k, 1'. T. , Optvratiüii (.haraitcristus ol the Sandia Itiü K^^ l'lasma Are Tunnel, (lo lir puhl usind .i.s Sandia ('ürporal ion Ke search Report).

7. Shipley, K. I.., Speetrographic Analysis of l'lasmajets Progress Report 11, SC'-4776(RR), Sandi.i Laboi-atür\, Albui|uei(|uc, March IKfüt.

8. Rynn, N. , " Macroscopit Transport Properties of a Fully Ionized Alkali-Metal Plasma," Plus, of Fluids, Vol. 7, No. 2, February 1904.

9. Hall, I.. S. , "Thermoelectric Kffects in a Joule -1 leated Plasma," phys. of Fluids, Vol. 7, No. A, March 19C4.

10. Cowling, I". G. , " Magnetohydrody na mic," Interscience Publishers, Inc., New York, No. 4, 1957.

1 1. Lewis, II. U. , Heitz, J. R. , "Kfficiency ol the Plasma Thermocouple," ,1. Appl. Phys. Vol. il. No. 4, April PJfiO.

Lamb, II. U . , "A Genera! Theory for the Flow of Weakly loni/.ed Gases," A1AA Journal Vol. 2, No. 2, February 1964.

4 7

\)\> I Kl Ml In )V I ( I . . M i> .il I 1I11 .II\ W.i.sluni'N.i! I) ( Ci)

\i'io-'l'lifiinods n.unii-.s Si.i lula rd I )i,st iilnil ion ( 1 tlj )

Dl II i i^')) i i I'S (7 J)

i M ih \1 S\\( \M;i ( lucf Mail .nid Miss.ige l)i\.

IT DAS \ (53)

I'lll'D-loi r ( Ottil-, N-'l, I . \S1.

1 ' i nl \\ \^ ( i IM nni'inaiin

I )cp.irt nit-iit ol I .hi l r u ,i I I jigim crmg

l'iu\ el-sits ol N'fv, Mcxuo

Uluiqucrijuc New Mi'XK o

( Ol. 1) M.llillrk.iun

Hallustu Missilr Hi-criti\ Syslcins

Ha 11 ist u Systems I )i\ us ion ( \1'S(.')

N'oiton \ii I'otii' HaSi', California

I ilis I. l-'ostiT, .1 r.

\(l\aiued Materials TcchnologN M.ittelle Memorial Institute

,r)ÜJ Kl M^ V. enue C Olumlius 1 , ( )hio (i)

C 1- Mild, 1100

1.. \ liopkms. 1 (00 .1 II Kindlay, HOO

\\ \ GardiH-r, 1500 I.. U Smith. I'.OO

C S Si'lvagc. lti.il

I' B. Ik-apln. Mil

I.. 1) I'attorson, 3411-1

For II. I-' Carroll, I'SAIX' Bertha li. Mien, 3421

Mavis c; Handle. i42H- 1. Bld(> 1)31. Mas is c; Handle, 342H- 1 . Hldg. HBO

H S. Claass« n, 5100

() M. Sluetzei, 5140

.1 H Hamster, 5153

1 H ( uok .li i40ü H \1 Met/ Mill.

I. i: llollingsworth 7200

I) H Sinister 7400

V I. Blake, .Ir 7410

\ V Hope, 7120

II H \'aughn, 7-12 1 (5)

K .1 Tours an 7421-1 (5)

H C Mavdew 7-122

U II (uns, 742-1

M I. Kramm, M30 I. Ciutierrez HlOO 1) H ( oltei , 'HOO H ( Smeli. h, 3427- 3 t 10)

K \l H. \ Me\. 117 177 (( ode 143H) (It)

■lit