1

national accelerator laboratory TM-434 0621.05

EPB DIPOLE MAGNETIC FIELD MEASUREMENTS R. Juhala

July 26, 1973

This report consists of a collection of measurements made over

the past two years on the external proton beam 10' dipole magnet

(NAL designation is 5-1.5-120). Three separate groups have measured

the various aspects of the field. The resulting reports are included

hereinti each as a separate appendix.

The magnet is described in various,NAL drawings li however the

essential features are reproduced here in Figure 1. The magnet has

32 turns and a gap of approximately 4 cm. This design has a ratio of

B/I of about lOkG/kA.

The d.c. resistance of this magnet is ,X7.4 2 0.3 mS2, The

parallel inductance (Lp) and quality factor (Q) are shown in Figure 2

as a function of frequency. The Q is, of course, significantly smaller

for magnets with a vacuum chamber

parallel and series inductance is 7

in place.

Ls =i Q" T

I- + Q2 yP

the quality factor is defined as Q = k P

parallel resistance in the diagram below. I.

The relationship between

where R is the P

A NAL Drawing Nos. 0621-ME-19417, 0621-MD-19418.

c Operated by Universities Research Association Inc. Under Contract with the United States Atomic Energy Commission

FIG. I Cross-sectional view of EPB dipole

I -I-- l

-

---.---____ - -__

I

FIG. 2

3 I I I

TM-434 0621.05

I I

EPB dipole

PARALLEL INDUCTANCE &Q vs FREQUENCY ( INDUCTANCE UNITS ARE MILLIHENRIES)

1 V,C,= MAGN.ET WITH VACUUM CHAMBER)

100 200 400 600 FREQUENCY (H z)

800

4

APPENDIX A

TM-434 0621.05

TOr BEAM TRANSPORT MAGNET ENTHUSIASTS

FROM: TOM WHITE

SUBJECT: PROFILES & EXCITATION CURVE FOR "TYPICAL" B-T DIPOLE

DATE: JULY 5, 1972

The accompanying curves depict magnet measurements taken personally

by me last 23 and 24 of Febr-uary on a certain beam transport dipole

made available to me. This particular magnet bore no serial number

that anyone could find and has been designated by me (perhaps some-

what unjustly) as "typical". It's whereabouts is not known to me,at

this time, but I suspect it was destined for the M-2 meson lab beam.

R. Juhala may know.

Fields were measured by a rotating coil Gaussmeter which, together

with the power supply, was stable to 2 .05%. Juhala calibrated it

with an NMR device. The current was monitored using a toroidal

transducer bucked by a null-reading Fluke meter. Our absolute un-

certainty in current is limited to about + .25% by knowledge of

the resistance of a certain water-cooled shunt used to calibrate

the transducer. (J. Ryk is the expert on this). This means that

if anyone cares to measure the shunt more carefully, the current

readings can probably be corrected to yield an absolute accuracy of

around 2 .05%,(the gaussmeter measures field at a point).

Thus, our data on fields are good to f<.l%, and the current tot+*+&25%.

The original data reside in a notebook labelled: Bill Lord...Magnet

Testing Environmental & Special Magnets...6 May 71 to=*="

5

APPENDIX B CSTL Internal Report No.

D. J. Mellema A. V. Tollestrup January 29, 1973

M2B6 Magnet Measurements of January 21-22, 1973

This report describes a series of measurements made on an EPB

dipole magnet located in the Meson Laboratory M2 beam line and des-

ignated M2B6. The magnet is powered by a Trans-Rex power supply in

series with three other EPB dipoles (M2B7, 8, and 9). The maximum

current obtained with four magnets in series was 2000 amp, limited

by the Trans-Rex top DC voltage of 200 V. By shorting out M2B9, we

were able to obtain a current of about 2500 amp at 200 V. Magnet

current measurements were made using a DVM to read out the transductor

voltage in the power supply. (Trans-Rex claims an accuracy of + 0.15%

over the full range of currents monitored.)

The value of B dl was measured on January 22, 197:3i as a

function of current, by integrating the signal from a coil centered

by eye on the beam center line and lying about 5/32' below the magnet

midplane. (The field is known to be uniform to about 0.1% within

+ 1" of the center line.) The probe consisted of one turn of magnet

wire wound on a l/2" wide Al bar, 12 feet in length. The Al bar was

mounted on a piece of 3/4" Al angle to give it greater rigidity. The

far end of the coil was centered between M2B6 and M2B7.

The effective width of our coil loop is 1.321 cm, probably good

to I%, and the time constant of our integrator is 0.02521 set,

probably good to 0.1%. The (B dl measurements were taken in two

6 TM-434 0621.05

groups, each ranging from 100 to 2500 amp. Each measurement is the

average of one integration from zero current to the current being

measured, and another integration back down to zero. Drift currents

contributed's typical uncertainty of 0.5% at 100 amp, the lowest

current studied and proportionately less at higher currents. The

results of our two groups of measurements are listed in Table I and

illustrated in Figs. l-3. Figures 2 and 3 show the high g region of

Fig. 1 on an expanded scale. The crosses indicate measurements from

group 1, and the dots or open circles represent the group 2 measure-

ments.

The group 2 measurements were taken with somewhat smaller observed

drift currents and should be more accurate than the group 1 measure-

ments. Using a Hall probe with quoted accuracy of p" l%, T. Yamanouchi

obtained a central field measurement of 17.84 k Gauss at 2500 amp, in

good agreement with our result. The I/B curve appears to have a

slightly negative slope in the low E region, possibly due to non-

linearity of the transductor output at low current. There is also an

anomalous point at Ss = 1.017 k Gauss which we cannot account for;

since this was the first point taken in the first group of measure-

ments, it may have been misread.

On January 21, 1973, we studied the water temperature rise in

M2B6, 7, 8, and 9 as a function of current. The temperature was

monitored by eight thermocouples, two on each magnet. There are four

parallel LCW paths in each magnet. We monitored the uppermost path in

each magnet at the elbow where the water exits. We also monitored the

two innermost paths at the "tee" where they recombine. The change in

-7 TM-434 0621.05

temperature for each thermocouple was recorded, allowing about 15

minutes after each change in current for the magnet to reach thermal

stability. (The temperatures were observed to remain constant after

about 5 minutes.) The readings were corrected for changes observed in

the supply temperature. Our results are shown in Fig. 4. The

temperature rise is nearly linear with 12, as expected. When we

attempted to run at I = 2500 amp, the plastic connecting hoses on the

LCW return lines ruptured before we reached thermal equilibrium.

3 TM-434 0621.05

Table I

/ B dl Measurement on M2B6

I (transductor) / B dl r=Pl [k G - m]

First Group 99 239.5 319.5 410.5 525 578.5 686

;I;: 996.5

1093.5 1160.5 1291 1400 1481 1581 1664.5 1762.5 1873.5 1955 2011 2049.5 2151.5 2172 2232 2301.5

E 2463 2503.5

3.100 7.632

10.21 13.11 16.78 18.56 21.98 25.25 28.54 31.83

2*:98 ;;:g ;p;

4$:85 47.25 48.65 49.61 50.24 50.63 51.65 51.82 52.37 52 -97 53.17

;zii 54:35

‘li= r ; d1 (L=lO')

Ik Gl

1.017 2.504 3.349 4.301 5.506 6.091 7.211 8.285 9.365

10.44 11.41 12;oo 12.99 13.67 14.10 14.64 15.04 15.50 15.96 16.28 16.48 16.61 16.95 17.00 17.18 17.38 17.44 17.62 17.74 17.83

;;*g ;;:g

95: 36 94.98 95.13 95.35 95.46 95.44 95.82 96.68 99.39

102.43 105.06 107.96 no.65 113.69 117.37 120.12 122.01 123.39 126.97 127.75 129.92 132.44 133.81 136.54 138.81 140.40

3 TM-434 0621.05

Table I (cont'd)

I B dl Measurements on M2B6

I (transductor) [amp1

‘ij’ = uu (L=l-1) /Bdl L

[k G - m] fk Gl

Second Group 125 226 325 425

Es 712.5 786 893.5 9%

1053.5 11% 1284 1390 1525 1556 1696.5 1780 1887.5 2025 2085.5 2200.5 2285.5 2367.5 2501

3.988 7.174

10.34 13.55 16.37 19*59 22.73 25.15 28.46 30.59 33.61 37.34

47.44 48.78 50.36 51.00 52.10

1.308 2.354 3.393. 4.444 5.371 6.426 7.459 8.250 9.337

10.04 u-103 12.25 12.93 13.60 14.36 14.52 15.20 15.57 16.00. .16.52 16.73 17.09 17.32 17652 17.82

95.54 96.02 95.79 95.62 95.33 95.48 95.53 95.27 95.70 95.24

;:*2 99:31

102.19 106.20 107.16 111.64 114.36 117.94 122.56 124.64 128.74 131.93 135.15 140.36

ICI

APPENDIX C

Relative and Absolute Measurements of the Quantity B dl Across the Horizontal Gap an an EPB Dipole

TM-434 0621.05

P. Baranov: S. Rusakov+ J. Orear ++ and R. Juhala

June 13, 1973

Using a long flip coil and an integrator, measurements were

made of the integrated bending length in an EPB dipole. The absolute

value of I BYdz is tabulated in the table below and plotted in

Figure 1 (B Y is taken here as the strong component of the transverse

field, with z being the axial coordinate). Also shown are measure-

ments of B Y at a point well inside the magnet vs. current. The

measurements are accurate to within + .15%.

The flip coil consisted of two turns of .004" diameter tungsten

wire stretched between two supports. This stretched wire flip coil

had a square cross-section . 504" on a side and extended 1 l/2 feet

beyond the ends of the magnet into essentially zero field. Figures

2 through 7 show the relative field strength as a function of the

horizontal position(x coordinate) at 1400 and 1688 A. Measurements

were made of Bydz on the midplane (y=o) and 3/8 in. below the midplane,

and of Bxd$; 3/8 in. below the midplane. The relative shape for

+ P. N. Lebedev Physical Institute, Moscow, USSR

++ Laboratory of Nuclear Studies, Cornell University, Ithaca, N.Y.

TM-434 0621.05

11

f Bydz (Figures 2 through 5) is precise to better than .05% in the

regions where it is essentially uniform (x =' + 1.5 in.). Outside

this ,region the finite width of the coil introduces errors on the

order of + . 15% due,to higher order components in the field. The

relative shape for the component Bxdz (Figures 6 and 7) is precise

to within + 2%. The most significant error in this measurement is due

to the uncertainty (-f. lo) of the orientation of the flip coil. This

same uncertainty introduces an error in s Bydz of less than .02%. The

variation offBydz with the y coordinate was observed to be less than

. 04% over the region y=t 3/8 in. and x=0.

12

TABLE II

TM-434 0621.05

J!Ieasurements of Bydz and B Y as a function of current for

an EPB dipole (AircoTemescal Magnet #71)

Current (A)

0 --

199.9 6.43

400.0 12.82

600.4 19.26

800.2 25.60

999.9 31.85

1200.1 37.63

1399.8 41.64

1600.1 44.92

1687.0 46.17"

1700.2 46.35

1800.1 47.68

1900.3 48.90

2000.5 50.05

Current (A) BJkG) 1

0 <lo gauss

200.1 2.101

400.0 4.208

600.5 6.307

800.3 8.340

1000.4 10.43

1199.9 12.34

1400.5 13.65

1600.2 14.72

1689.1 15.16

-- --

1800.7 15.67

--

--

--

--

*This is not a measured point.

INDUCTANCE: Q

I -

14

TM-434 0621.05

IC

4

;

(

1

I-

i-

j-

r -

2 -

3- -11

I I I I FIG. A-l EPB dipole

TYPICAL END FIELD X=O,Y=O ‘, ClJRRENT=967A CENTRAL FIELD -10.10 rtG

EDGEOF IIRON YOKE

-

5 GAUSS

lg I 0 -5 0 IO 15

AXIAL POSl.TloN (in)

15 TM-434 0621.05

IO2

9.!

I I I I I FIG.A-2 EPB dipole

TYPICAL TRANSVERSE FIELD PROFILES -- --- 1550 A

967 A

f -c,

f

. s-. -.-a-.-w y,

i

s

l

I

I I I I I

-2 -I 0 +I +2 TRANSVERSE POSITIONJ (IN,)

14.5

16 TM-434 0621.05

II I I I I III I IIll 1 I 8

14 r FIG, A-3 --- rt. /

12

t

EXCIT&TlON CURVE

IO

8 r

6

0 -4 b&l

s -6 GI

-8

Ii I I I I I I t I t I III -lH4-12-10-8-6-4-2 0 2 4 6 8 IQ I2 I4 I6

CURRENT, HUNDREDS OF AMPERES

122

120

118

II6

114

II2

IIC

Ia

IOi P IO

IOi

10

9t

9i

94

P

I I I

FIG. B-l \

-

-

-

-

-

-

-

-

-

-

EPB dipole

2500A

I I

a

TM-434 0621.05

240 250 260 Gel& I 1 I I I I

FIG, B-3 EPB dipole-

I HO- 2500A

‘38- I iss -

3: hd)34 pi g32 -

51 Do-

q 28-

p- I !24-

I 22- I I I 1

16.5 17.0 1x5 l&O B L-iGj

TM-434 0621.05

0 INNER PATHS X UPPER PATH >

M 286

+ iiiNER PATHS 0 UPPER PATH. >

M2B7

A I’NNER PATHS V UPPER PATH >

M2B8

CB I’NNER PATHS 0 UPPER PATH >

M2B9

IX.. B-4 EPB dipok

TM-434 01

FI G.C-I 21

EPB dipole

I By(o)W SMALL STANDARD COtt AND FIELD INTEGRAT +----

8 By’Co) dl WITH STRETCHED. WIRE ,+

t’

0.2 0.4 0.6 0.8 I.0 I,2 I.4 l-6 1.8 2.0

CURRENT( KA)

I I I F IG.C-2 EPB di.pole CUR REN T = I400

.’ I I

x(iri) [By odd l/$yb)dI -4.5

y=o

I By(o) dI=4L64KG-n7 -

-.

-

-

-

-

-

-

-

-

-4.0 -3.5 -3.0 -2.5 -2eo -I 05 -I .o - .5

O IO .5

I a0 I .5 2.0 2.5 3.0 315 4 .Q 4.5

.I 209 -2063 *318l .4773 JO61 .9327 1.000 2 1.000 I .9999 I.0000 .9999 1.0004 .9988 .9\07 ‘6724 ,4528 .3017 .I 943 .I114

-

I -

i-

1 I I 1 I I I I I I t% \ -6 -5 -4. -3 -2 -I 0 +I +2 i-3 +4 +5 +6

G gP

-

x POSITION h\

LO

,9

.8

.7

,6

-

-

F-

FIG. C-3 j@By(x) dl/ IByb\dI vs x EPB dipole CURRENT 1400A

y=ti375 in

I By(o)dl=41.6‘11(G-rn

x(h-9 -4.5 -4,0 -3.5 -3.0

JBy(r)dl/ lByb)d I .I I84 .I 997 .3064 .4574

-2.5 .6974

1 ! I ! I I I 1 f -6 -5 -4 -3 -2 -I 0 +I +2 3-3 -54 4-5 +6

-$0 I.00 27 -I -5 I.01 I 2 -I -0 - .5

0.0 .5

I .o I .5 PO : 15. b -0 b.5 4.0 k.5

3989 l 9997 I ,000o .9999 .999 I 1.0154 r-J -9728 w .6505 ‘4285 .2869 ,I852 .I295

I,0

.S

,8

FIG. c-4 fBy(X)dl/lBy(o) cjl vs x EPB dipole CURRENT=l688A

Y = -;375in,

f By(o\dl =46.19I(G-tn

-

-

I I I ! I I i 1 -5 -4 -3 -2 -I Q +I t2 +3 +4 -6 +6

- ;4.0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -! 45

CL0 .5

(,O 13 Lo 2.5 3.0 3.5 ?.,O 445

. 167 I -I 973 - 3039 ,45 41 .6920 .9984

I 0091 .99ti3 2 9996

I ,000 a997 ,9983 I ,013s .9720 .6525

l 4300 l 2870 .I849 .I267

-

- -E

-

X POSI TlON(i n)

FIGS-5 EPB dipole IBy dl/fByl@dl vs x

CURRENT’ 1688 A y=o

I By(o) = 46.19 KG = rn

x (in) - 4.5 - 4.0 ,2062 -3.5 .3182 -3.0 .4777 -2.5 ‘7044 - 2.0 ,92 94 -I l 5 -1.0 - l 5

0.0 ..5

I 0 r:s 2.0 z-5 3.0 3 ,-5 4*0 4..5

.9983 l 9995

,9998

1,000 -9997 ,9996 .9964 ,907l .67Ol ,452O .3008 .I926 * 1090

-

- r-2 h-l

-

-

26

-

-

-

FlG.C-6 EPB dipole

I Bxd I vs x CURRENT MOOA

Y- - -3/s:’

TM-434 0621.05

I I I I I I I I I ! I “- 5 -4 -3 -2 -I 0 I 2 3 4 -5

x POSIT ION (in)

27 TM-434 0621.05

IC

8

6

A

n

&

J 2 &J G

xc rm

-2

-4

-f

-e

-lC

FIG C-7 EPB dipole

1 I ! 1 [ 1 -5 -4 -3 -2 -I 0 I 2 3 4 5

x POSITION&n)