ess 261energetic particles1 energetic particles & boundary remote sensing energetic particle...

ESS 261 Energetic Particles1

Energetic Particles & Boundary Remote Sensing

Energetic Particle Instruments: Operation and Data ProductsGeometric Factor. Contamination: Sunlight, Earth-glow, Neutrals

Background/Electronic Noise, Detector Capacitance and Leakage Current.Data Viewing, Removal of Noise and Analysis of Distribution Functions

Access, Use and Pitfalls of Analysis in Various Regions:Solar Wind, Magnetosphere, Radiation Belts and Ring Current

Remote Sensing of Particle Gradients: Magnetopause, Inner Magnetosphere and Low Frequency Waves

Contributions from:”Davin Larson, Thomas Moreau, Andrei Runov and Ryan CaronReferences: ISSI book on Analysis Methods for Multi-Spacecraft Data

ESS 261 Spring Quarter 2009

Lecture 05April 27, 2009


Interaction of particles with matter [1]• The way in which energetic particles interact with matter

depends upon their mass and energy.– Photons - have “infinite range”- Their interaction is “all-or-nothing”

They do not slow down but instead “disappear”, typically through one of three interactions (I=I0e-x where is absorption coefficient ):

• Photoelectric effect (Low energy: E<~50 keV

• Compton Scattering (50 keV ~< E < 1 MeV)

• Pair production ( E >2 x 511 keV).

– Particles with non-zero mass (Electrons and Ions) will slow down as they pass through matter. They interact with electrons, phonons and nuclei.

• Electron interaction is long-range. Enectron-electron energy exchange peaks when incoming particle is close to the target electron energy. The material electrons have energies that are determined by

– The material temperature (phonon-electron interaction couples them) ~kT, ~105m/s

– The Fermi energy, i.e., the energy level of free electrons in absolute-zero temperature. This is about 5-10eV, which gives the Fermi speed of 106m/s.


Photoelectric effect

Compton scattering

Pair production


(/ often used: mass attenuation coefficient)


Interaction of particles with matter [2]• Charged particles primarily interact with the

electrons in a material. Typically the energetic particle suffers numerous, distant collisions with a Fermi sea of electrons losing a small amount of energy with each interaction (much like a plasma!).

• The interaction is typically strongest when the velocity of the energetic particle is approximately the same as the Fermi speed.

• Energetic neutral atoms are quickly ionized soon after entering the solid.

• Neutrons are a different matter altogether


• The stopping power for heavy particles (ions) is given by the Bethe-Bloch formula (1932):

Interaction of particles with matter [3]

: where,4

22

42

Bcm

ezN

dx

dE

e

A

2)1(

2ln 2

2

22

Z

C

I

cm

A

ZB e

Rate of energy loss is ~ inversely proportional to energy, and proportional to Z (the atomic number) and z2, z the projectile chargeI = average ionization potential, and C = density and shell corrections.


• The range is given by:

– dE/dx is often expressed in units of keVcm2/gr which is dE/dx times the material density. This bundles the dE/dx curves into groups by normalizing away the material density from the electronic interactions.

– The range (typically in cm) is also often normalized to the density and expressed in units of grams/cm2, i.e., the equivalent mass per unit area required to stop the particle.

Interaction of particles with matter [4]

This formula is only useful for ions for reasons we will soon see.

dEdx

dER

Estart

0 1


Interaction of particles with matter [8]• Electrons and Ions behave differently due to the

different mass ratio. The primary interaction of all energetic particles is with the sea of electrons.– Ions:

• Ions interact with a series of distant collisions. Each interaction results in a small energy loss and very little angular scattering. – They travel in nearly straight lines as they slow down. The dispersion is small. (Imagine a fast bowling ball thrown into a sea of slow moving ping pong balls.)

– Electrons:• Electrons can lose a large fraction of their energy and undergo large

angle scattering with each interaction (Imagine a high speed ping pong ball thrown into the same sea)


Interaction of particles with matter [9]• When an electron hits an atom it can undergo a very large angle

deflection, often scattering it back out of the material.

• Bremstrahlung (braking) radiation is produced when electrons undergo extreme accelerations. X-rays are easily generated when energetic electrons strike high Z materials. (a good reason to avoid high Z materials on exposed surfaces)


Protons in

Energy lost to ionization (collectable)

Energy lost to phonons (not collectable)


Alphas in:

Energy lost to ionization (collectable)

Energy lost to phonons (not collectable)


Electrons in

Energy lost toionization(collectable)

Energy lost toBremstrahlungradiation (notcollectable)


Solid State Detectors• Solid State Detectors (SSDs) not only detect individual particles, they can be

used to measure particle energy with good energy resolution.

• Typically only good for E>20 keV

• Recent improvements push the limit to ~2 keV

• Two varieties of Silicon Diode Detectors– Implanted Ion (i.e. Canberra PIPS)

• Produced by implanting p-type material into an n-type silicon substrate

• Easy to produce pixelated surfaces

• Very rugged

– Surface Barrier• Chemical process to create diode surface

• Easily damaged, sensitive to solvents

• Not too common anymore

• Typically both varieties are run fully depleted (electric field extending throughout bulk of material)

• Maximum thickness is ~1000 microns – defines max energy particle that can be stopped within the detector

• Particles can be incident on either side of detector


Operation Principle• With the application of a (large enough)

reverse bias voltage an electric field is established throughout the entire silicon volume (fully depleted detector).

• An energetic charged particle will leave an ionization trail in its wake.

• The electron hole pairs will separate and drift to opposite sides.

• The total charge is proportional to the electronic energy deposited. (3.61 eV per pair for Silicon).

• The signal contains only a few thousand electrons thus requiring sensitive electronics.

• The trick is to collect and measure this small signal.

p n++

--

E

p n++

--

E

Forward bias

p n++

--

E

Reverse biasparticle

-+


Detector Electronics

Simulated A225response for typical 1MeV electron pulse through a Si detector.

The A225 integrates charge, with peak pulse equal to integrated charge.

A 20ns signal turns into an 8usec pulse!


Front End Counting Electronics


Sources of Noise• Capacitance

– Noise results inuncertainty inabsolute valueof energy

• Leakage (dark) current– When dark current is integrated by A225 results in baseline offset– Baseline restorer restores zero level– Leakage current results in error in absolute signal amplitude


Examples of Detector Systems: WIND/3DPPredecessor of THEMIS/SST


Cross section of the EPACT isotope telescope on Wind. The first two detectorsare two-dimensional position sensitive strip detectors (PSD1, PSD2). They are requiredso that path-length corrections may be made for the angle of incidence and fornon-uniformities in detector thickness. Tungsten rings are used to mask off circular areasfor each PSD. There are 6 solid-state detectors increasing in thickness with depth in thestack in order to minimize Landau fluctuations. From von Rosenvinge et al. [1995].

Examples of Detector Systems: WIND/EPACT


Examples of Detector Systems: THEMIS/SST

Attenuator

Foil

Magnet

Detector Stack

Attenuator

Foil Collimator(for electrons)

Open Collimator(for ions)


THEMIS/SST Sensor Unit Schematic

FoilCollimator(electron side)

Thick Detector

Sm-Co Magnet

Attenuator

Al/Polyamide/Al FoilOpen Detector

Foil Detector

Attenuator

Open Collimator (ion side)


• Each sensor unit is a:– Dual-double ended solid state telescope

– Each double ended telescope (1/2 sensor) has:• Triplet stack of silicon solid state detectors

• Foil (on the side measuring electrons)– Filters out ions <~350 keV

– Leaves electron flux nearly unchanged

• Magnet / Open (on the side measuring ions)– Filters out electrons <400 keV

– Leaves ion flux nearly unchanged

• Mechanical Pinhole attenuator– Reduces count rate during periods of high flux

– Reduces radiation damage (caused by low energy ions) during periods of high flux

• Collimators

• Preamplifier / shaping electronics

THEMIS/SST Sensor Unit Details


Detector Pixelation• Detectors similar to STEREO/STE

– Produced at LBNL/Craig Tindall PI

Active area

Guard ring

10 mm

5 mm

Additional Pixels not used for Themis


T Out

+4.5 V

-2.5 V

O Out

-35 V

F Out

F Test in

T Test in

O Test in

~200 A Polysilicon + ~200 A Al

pn

np

np

pn

~200 A Polysilicon

T

F

O

300 micron thick detectors

225FB

225FB

225FB

Outside Grounded

Pixelated side ~1200 A Dead layer

Detector Wiring


• Typical Electrical Connection Between Detector and Flex-Circuit

SST Detector Mechanical Design/Connections

Kapton Flex-Circuit

Detector (pixelated side)

Wirebond Loop

(NOT to scale – actual loop height < 300 micron)


Detectors (4)

Spring Clamp

Spring Plate (2)

• Detector Board Composition (exploded view)

PEEK Spacer (4)

BeCu Gasket (3)

Kapton Flex-Circuit (4) AMPTEK Shield

KaptonHeater

Thermostat

• DFE Board Subassembly

SST Detector Mechanical Assembly


SST Detector Mechanical: Real Life


• DFE Board Subassembly Relative Positions • (2 per sensor)

AMPTEK Shielding

Detector Stack Subassembly

Multi-Layer Circuit Board (62 mil thickness)

Foil Frame

Thermostat

SST Mechanical Design


SST Mechanical Design• Magnet-Yoke Assembly Co-Fe Yoke (2)

Sm-Co Magnet (4) (currently not visible)

Aluminum Magnet Cage


• Attenuator Assembly

Attenuator (4)

Cam (2)

SMA Lever (2)



• Actuators and Position Switches

Honeywell SPDT Hermetically Sealed Switch (2)

SMA Actuator (2)



• Two Collimators Per SideElectron Side

Ion Side



• Four Collimators Per Sensor

Ion Side

Electron Side

Electron SideIon Side



• Support Structure • (back section)

Electrical Connector

Bottom Closeout Panel

Rigid Mounting Flange



• Support Structure • (front section)

Kinematic Flexure (2)

Rigid Mounting Flange



• Bi-Directional Fields-of-View



• Sensor Orientation Relative to Spacecraft Bus



• Sensor Unit Mounting Using Kinematic Flexures– Each sensor mounted to spacecraft panel at three points

• One rigid mounting flange• Two mounting flanges with kinematic flexures

– Allows relative motion due to CTE differences between sensor structure and spacecraft panel• Predicted expansion differential along instrument axes with 120

ºC temperature gradient:– X-Axis: 0.006” (0.15 mm)

– Y-Axis: 0.013” (0.33 mm)

– Flexure dimensions sized to keep maximum bending stresses below 6061-T6 yield strength• Factor of Safety (F.S.) > 1.4 per NASA-STD-5001



• Attenuator Actuation – CLOSED position

Honeywell Switch (extended-position)

SMA Actuator (extended)

Honeywell Switch (compressed-position)

SMA Actuator (retracted)



• Attenuator Actuation – OPEN position

Honeywell Switch (compressed-position)

SMA Actuator (retracted)

Honeywell Switch (extended-position)

SMA Actuator (extended)



• Linear Actuators– Shaped Memory Alloy (SMA) actuator– Single direction 125 gram pull-force

• Required force < 42 gram => F.S. > 3.0– Operating temp range: -70°C to +75°C

Extended Position

Retracted Position

Relative Size(commercial model shown)


Magnetics Testing• Magnet Cage assembly #1

• Measured Py for 19 magnets (All values were very close)

• Selected 4 magnets for assembly #1

• Measured dipole and quadrapole moments of assembly

• Found significant residual dipole moment along x-axis

• Contribution of dipole and quadrapole nearly equal at 2 m

• Conclusion: Px and Pz of individual magnets are important


Magnetics Testing• Sent Magnet Cage assembly #2 to UCLA for testing

• Results are virtually the same

• Contribution of dipole and quadrapole fields are similar at 2 m:– B(dipole @ 2m) = .88 nT

– B(quad @ 2m) = .59 nT

• The sum of both contributions exceeds requirement (0.75 nT @ 2m)

• Relaxed requirement, since it is a DC field

-350

-300

-250

-200

-150

-100

-50

0

50

100

150

0 100 200 300 400 Series1

Series2

Series3


Electronics Block Diagram• Signal chain: 1 of 12 channels shown

ADC

FPGACoincidence

Logic &Accumulators

Memory

DACThresh

Gain

PD

BLR

A225FPreampShaper

DFEBoard

DAP Board

Test Pulser

Bias Voltage


FPGA Functions: Interface to ETC• Using Actel RT54SX72S (modeled on STEREO/STE)

– Controls 12 ADCs• Monitor / Count threshold events• Monitor peak detect signal• Produce convert strobe• Coincidence detection• Readout ADC (energy)

– Psuedo-logrithmic energy binning• ADC measurement used as address of LUT to increment accumulators

(LUTs and accumulators stored in SRAM)

– Data Readout (controlled by ETC board)– Command Data Interface (CDI) (loads tables)– Test Pulser control– Noise measurement

• Periodic conversions to measure “noise”

– Analog Housekeeping control


SST Products• Products: Full, Reduced (Burst is same as full)

– Full: 16E x 64A– Reduced: 16E x 6A , or

16E x 1A (omni)

• Modes: Slow Survey, Fast Survey, Particle Burst• Slow Survey:

– Full distributions (ions and electrons) at 5min resolution– Reduced, omnidirectional distributions: every spin

• Fast Survey:– Ions: Full distributions every spin– Electrons: Reduced distributions (16E x 6A) every spin

• Burst:– Ions: same as above– Electrons: Full distributions every spin


SSTs

Angelopoulos, 2008

SST Accommodation


Angelopoulos, 2008

SST Accommodation


Data Analysis Tools [1]• Pitfalls

– Sun contamination• ; Sun contamination is masked on board but often fails

; Use keyword: mask_remove to removed masked bins and interpolate across sectors

• ; Sun contamination is lefted unmasked recently (and most of the time) on board ; There is code to recognize the faulty bins (saturated) and remove them altogether.; This is called : method_sunpulse_clean='spin_fit' , or ‘median’ and tells the; programs to remove data beyond 2sigma away from spin-phase fit/median.

• ;Sun contamination/saturation also affects other channels due to electronic noise.;The code can remove the typical noise value and provide the remaining good; signal (assuming no saturation). The keyword is: enoise_bins and the; procedure is documented in: thm_crib_sst_contamination.pro


Sun contamination (thm_crib_sst_contamination.pro) – ;PROCEDURE: thm_crib_sst_contamination

– ;Purpose: 1. Demonstrate the basic procedure for removal of sun contamination,

– ; electronic noise, and masking.

– ; 2.. Demonstrate removal of suncontamination via various methods.

– ; 3. Demonstrate the correction of inadvertant masking in SST data

– ; 4. Demonstrate scaling data for loss of solid angle in SST measurements.

– ; 5. Demonstrate substraction of electronic noise by selecting bins in a specific region

– ; 6. Show how to use these techniques for both angular spectrograms,energy spectrgrams, and moments.

– ;SEE ALSO:

– ; thm_sst_remove_sunpulse.pro(this routine has the majority of the documentation)

– ; thm_part_moments.pro, thm_part_moments2.pro, thm_part_getspec.pro

– ; thm_part_dist.pro, thm_sst_psif.pro, thm_sst_psef.pro,thm_sst_erange_bin_val.pro

– ; thm_crib_part_getspec.pro

Sun contamination (sst_remove_sunpulse.pro) – ; Routine to perform a variety of calibrations on full distribution sst data. These can remove sun

contamination and on-board masking. They can also scale the data to account for the loss of solid angle from the inability of the sst to measure directly along the probe geometric Z axis and the inability to measure directly along the probe geometric xy plane.(ie X=0,Y=0,Z = n or X=n,Y=m,Z=0, are SST 'blind spots') THM_REMOVE_SUNPULSE routine should not generally be called directly. Keywords to it will be passed down from higher level routines such as, thm_part_moments, thm_part_moments2, thm_part_dist,thm_part_getspec, thm_sst_psif, and thm_sst_psef


Data Analysis Tools [3]• Pitfalls

– Sun contamination– Read crib sheets: thm_crib_sst_contamination.pro, and

documented procedure: thm_sst_remove_sunpulse.pro » ; » edit3dbins,thm_sst_psif(probe=sc, gettime(/c)), bins2mask» ; ON: Button1; OFF: Button2; QUIT: Button3» print,bins2mask

» thm_part_getspec, probe=probe, trange=[sdate, edate], $

» theta=[-45,0], phi=[0,360], $

» data_type=['psif'], start_angle=0,$

» angle='phi',method_sunpulse_clean='median',tplotsuffix='_ex2_t1',$

» enoise_bins = bins,enoise_bgnd_time=times,mask_remove=.99» tplot


Ground processing (particles only)• Pitfalls

– Sun contamination: Bin selection » ;


Density Correction• Interpolate densities• Add• date='2008-03-01'• startdate = '2008-03-01/00:00'• timespan,startdate, 4.0, /hour• Trange=['08-03-01/00:00','08-03-01/04:00']• Tzoom=['08-03-01/01:40','08-03-01/02:40']

• ;... select exact time interval to calculate join ESA/SST moments• tbeg = time_double(date+'/00:00')• tend = time_double(date+'/04:00')• ;select a probe• sc='b'• thm_load_state,probe=sc,coord='gsm',/get_support• thm_load_fit, level=1, probe=sc,

datatype=['efs', 'fgs'],/verbose• thm_cotrans,strjoin('th'+sc+'_fgs'),

out_suf='_gsm', in_c='dsl', out_c='gsm'• ;• ; SST now• thm_load_sst,probe=sc,lev=1• thm_part_moments, probe = sc, instr= ['ps?f'], $• moments = ['density', 'velocity', 't3'], $• mag_suffix='_peir_magt3', $• scpot_suffix='_peir_sc_pot';,/median• ; work in gsm• thm_cotrans,'th'+sc+'_ps?f_velocity',

in_coord='dsl',out_coord='gsm',out_suffix='_gsm'• ;• ; ESA now• thm_load_esa,probe=sc• ; Interpolate densities• tinterpol_mxn,'th'+sc+'_peer_density',

'th'+sc+'_peir_density',/overwrite,/nan_extrapolate• tinterpol_mxn,'th'+sc+'_ps?f_density',

'th'+sc+'_peir_density',/overwrite,/nan_extrapolate• …• ; ...total ion density• totNi = sst_i_n.y + esa_i_n.y

Ni

Ne


Velocity Correction• Interpolate densities• Add flux• ;• ; • ; ...sst Flux• sstFi = sst_i_v.y*0.• sstFi[*,0] = sst_i_n.y*sst_i_v.y[*,0]• sstFi[*,1] = sst_i_n.y*sst_i_v.y[*,1]• sstFi[*,2] = sst_i_n.y*sst_i_v.y[*,2]

• ; ...esa Flux• esaFi = esa_i_v.y*0.• esaFi[*,0] = esa_i_n.y*esa_i_v.y[*,0]• esaFi[*,1] = esa_i_n.y*esa_i_v.y[*,1]• esaFi[*,2] = esa_i_n.y*esa_i_v.y[*,2]

• ; ...total ion density• totNi = sst_i_n.y + esa_i_n.y

• store_data, 'th'+sc+'_Ni',$data={x:esa_i_n.x, y:totNi}

• options, 'th'+sc+'_Ni', 'ytitle', $'Ni !C!C1/cm!U3'

• ylim, 'th'+sc+'_Ni', 0.01, 1., 1

• ; ...total ion velocity (GSM)• totVi = esa_i_v.y*0.• totVi[*,0] = (sstFi[*,0]+esaFi[*,0])/totNi• totVi[*,1] = (sstFi[*,1]+esaFi[*,1])/totNi• totVi[*,2] = (sstFi[*,2]+esaFi[*,2])/totNi


Pressure Correction• Remove SST noise• Interpolate pressures• Then add• ;• ; SST now• ; SST now• thm_load_sst,probe=sc,lev=1• thm_part_moments, probe = sc, instr= ['ps?f'], $• moments = ['density', 'velocity', 't3'], $• mag_suffix='_peir_magt3', $• scpot_suffix='_peir_sc_pot';,/median• ; …interpolate• ; … add• ; ...pressure• ; ...SST: perpendicular temperature only• sst_Tperp = .5*(sst_i_t3.y[*,0]+sst_i_t3.y[*,1])• sst_i_p_nPa = 0.16*.001*sst_i_n.y * sst_Tperp • ; perp. pressure in nPa• store_data, 'th'+sc+'_psif_p_perp_nPa', $• data={x:sst_i_n.x, y:sst_i_p_nPa}• options, 'th'+sc+'_psif_p_perp_nPa', $• 'ytitle', 'sst Pi !C!CnPa'

• ; ...ESA: scalar temperature• esa_Ti = total(esa_i_T.y,2)/3.• store_data,'Ti_th'+sc+'_peir', $• data={x:esa_i_n.x, y:esa_Ti}• ; ...ESA ion pressure:• esa_i_p_nPa = 0.16 *.001 * esa_i_n.y*esa_Ti• ; scalar pressure in nPa• store_data, 'th'+sc+'_peir_p_nPa', $• data={x:esa_i_n.x, y:esa_i_p_nPa}• options, 'th'+sc+'_peir_p_nPa', $• 'ytitle', 'esa Pi !C!CnPa'

• ; ...Total ion pressure• totPi = sst_i_p_nPa + esa_i_p_nPa• store_data, 'th'+sc+'_i_p_nPa', $• data={x:esa_i_n.x, y:totPi}• options, 'th'+sc+'_i_p_nPa', 'ytitle', 'Pi !C!CnPa'


Finite gyroradius techniques• Ion Gyroradius large compared to magnetospheric boundaries

– Can be used to remotely sense speedand thickness of boundaries

– Assumption is that boundary is sharpand flux has step function across

• Application at the magnetopause• Application at the magnetotail

– Can also be applied to waves ifparticle gradient is sufficiently high

• Application on ULF waves atinner magnetosphere

Method exploits finite iongyroradius to remotely senseapproaching ion boundary andmeasure boundary speed (V⊥)

THEMIS

To EarthTo Sun

To Tail


At the magnetotaili,thermal-tail (4keV,20nT)= ~325kmi,super-thermal (50keV,20nT)= ~2200km

Plasma Sheet Thickness ~ 1-3 RE

Boundary Layer Thickness ~500-2000kmCurrent layer Thickness ~ 500-2000km

Waves Across Boundary: ~1000-10,000kmAlong Boundary: ~Normal : 1-10 RE

For magnetotail particles, the current layer and plasma sheet boundary layer are sharp compared to the superthermal ion gyroradius and the magnetic field is the same direction in the plasma sheet and outside (the lobe). This means we can use the measured field to determine gyrocenters both at the outer plasma sheet and the lobe, on either side of the hot magnetotail boundary.


Side View (elevations)

To Sun

SpinAxis

ESA:Elevationdirection(DSL)

SST:Elevationdirection(DSL)

25o

52o

-25o

-52o

11.25o

33.75o


Top View (sectors)For ESA and SST (0=Sun)

Spin motiondirection ( DSL)

11.25o

33.75o

To Sun (0o)

Spin axis

Normal to Sun, +90o


(a)

(b)

(c)

(d)

(e)

TH-B

(a)

(b)

(c)

(d)

(e)

TH-B

Particle motion directionCoordinate: ( DSL)Energy: 125-175keV

Note: direction dependson spin axis.

B fieldazimuth(solid white)

-B fieldazimuth(dashed white)

You care to time this!(+/- 90o to Bfield azimuth)


Multiple spacecraft, energies, elevations

A

B

D

E

….

Elev: 25deg E=30-50keV Elev: 25deg, E=80-120keV


Vi_const 310km/sec/keV fci_cons 0.0152Hz/nT B 30nTTi 40keV rho_ion 683kmTi 100keV rho_ion 1081km Ti 150keV rho_ion 1323km Ti 300keV rho_ion 1872km

SC E (keV) detectord (deg) r time B 40 SPW -128.0 683.4 11:19:29 B 40 SPE -52.0 683.4 11:19:39 B 40 SEW -155.0 683.4 11:19:18 B 40 SEE -25.0 683.4 11:19:42 B 40 NPW 128.0 683.4 11:19:29 B 40 NPE 52.0 683.4 11:19:38 B 40 NEW 155.0 683.4 11:19:24 B 40 NEE 25.0 683.4 11:19:43 B 100 SPW -128.0 1080.5 11:19:17 B 100 SPE -52.0 1080.5 11:19:42 B 100 SEW -155.0 1080.5 11:19:20 B 100 SEE -25.0 1080.5 11:19:45 B 100 NPW 128.0 1080.5 11:19:20 B 100 NPE 52.0 1080.5 11:19:45 B 100 NEW 155.0 1080.5 11:19:23 B 100 NEE 25.0 1080.5 11:19:48 B 150 SPW -128.0 1323.4 11:19:10 B 150 SPE -52.0 1323.4 11:19:44 B 150 SEW -155.0 1323.4 11:19:14 B 150 SEE -25.0 1323.4 11:19:51 B 150 NPW 128.0 1323.4 11:19:23 B 150 NPE 52.0 1323.4 11:19:45 B 150 NEW 155.0 1323.4 11:19:13 B 150 NEE 25.0 1323.4 11:19:48 B 300 SPW -128.0 1871.5 11:19:10 B 300 SPE -52.0 1871.5 11:19:44 B 300 SEW -155.0 1871.5 11:19:14 B 300 SEE -25.0 1871.5 11:19:51 B 300 NPW 128.0 1871.5 11:19:23 B 300 NPE 52.0 1871.5 11:19:45 B 300 NEW 155.0 1871.5 11:19:13 B 300 NEE 25.0 1871.5 11:19:48

Note:NEE= North-Equatorial, EastNPW=North-Equatorial, WestAngles measured from East direction-25deg elevation, 90deg East = SEE+52deg elevation, 90deg East = NPE… Spin axis

B

NPW

NEW

SEW

SPW

NPE

NEE

SEE

SPE

Boundary


Spin axis

BNPW

NEW

SEW

SPW

NPE

NEE

SEE

SPE

Boundary

V: NEE Part. direction

Hot/dense plasma

Cold/tenuous plasma Y

Z

GCNEE

n

Y

Y

n

Show: d=*sin(-)Note: d negative if moving towards spacecraft

d

SC


• Procedure– For a given , determine variance of data for all – Find minimum in variance, this determines (boundary direction)– Speed distance as function of time determines boundary speed

– intro_ascii,'remote_sense_A.txt',delta,rho,hh,mm,ss,nskip=13,format="(25x,f6.1,f8.1,3(1x,i2))"– ;– angle=fltarr(73)– chisqrd=fltarr(73)– for ijk=0,72 do begin– epsilon=float(ijk*5)– get_d_vs_dt,epsilon,hh,mm,ss,rho,delta,dist,times– yfit=dist & yfit(*)=0.– chi2=dist & chi2(*)=0.– coeffs=svdfit(times,dist,2,yfit=yfit,chisq=chi2)– angle(ijk)=epsilon– chisqrd(ijk)=chi2– endfor– ipos=indgen(30)+43– chisqrd_min=min(chisqrd(ipos),imin)– plot,angle,chisqrd– print,angle(ipos(imin)),chisqrd(ipos(imin))– ;– stop


Var

ianc

e,

2

Boundary orientation,

= 280o

Var

ianc

e,

2

Boundary orientation,

= 280o

1000

km

V ~ 70km/s

Z

Y

D

BA

• Procedure– Note two minima (identical solutions)

• One for approaching boundary at V>0• One for receding boundary at V<0

– Convention that d<0 if boundarymoves towards spacecraftallows us to pick one of the two(positive slope of d versus time)


Probe: TH-BAngle to Y_east=280degD0 = -2224 kmV0 = 69.9 km/stcross= 11:19:31.81

Time since 11:19:00

Bou

ndar

y di

stan

ce (

km)

Probe: TH-BAngle to Y_east=280degD0 = -2224 kmV0 = 69.9 km/stcross= 11:19:31.81

Time since 11:19:00

Bou

ndar

y di

stan

ce (

km)

tcross V [km/s] [deg]

D 11:19:27.6 75 270

B 11:19:31.8 70 280

A 11:19:38.4 80 275

Table 1. Results of remote sensing analysis on the inner probes

Timing of the arrivals of the other signatures at the inner three spacecraft


At the magnetopausei,sheath (0.5keV,10nT)= ~200kmi,m-sphere (10keV,10nT)= ~1000km

Magnetopause Thickness ~ 6000kmCurrent layer Thickness ~ 500km

FTE scale, Normal 2 Boundary: ~6000kmAlong Boundary: ~Normal : 1-3 RE

For leaking magnetospheric particles, the currentlayer is sharp compared to the ion gyroradius andthe magnetic field is the same direction in the sheath and the magnetopause outside the current layer. This means we can use the measured field outside themagnetopause to determine gyrocenters both at the magnetopause and the magnetosheath on either side of the hot magnetopause boundary.


C

DTH-B AE

Ygse

Xgse

C

DTH-B AE

Ygse

Xgse

Magnetopause encounter on July 12, 2007

(a)(b)

(c)

(d)

(e)

(g)

(f)

(h)

(a)(b)

(c)

(d)

(e)

(g)

(f)

(h)

Magnetic field angle is 60deg below spin plane and +120deg in azimuth i.e., anti-Sunward and roughly tangent to the magnetopause. The particle velocities, centered at 52deg above the spin plane, have roughly 90o pitch angles, with gyro-centers that were on the Earthward side of the spacecraft. The energy spectra of the NP particles show clearly the arrival of the FTE ahead of its magnetic signature, remotely sensing its arrival due to the finite gyroradius effect of the energetic particles. T=55s, i,100keV, 28nT) =1150km, V=40km/s


At the near-Earth magnetosphere



timespan,'7 11 07/10',2,/hours & sc='a'

thm_load_state,probe=sc,/get_supp

thm_load_fit,probe=sc,data='fgs',coord='gsm',suff='_gsm'

thm_load_mom,probe=sc ; L2: onboard processed moms

thm_load_esa,probe=sc ; L2: gmoms, omni spectra

tplot,'tha_fgs_gsm tha_pxxm_pot tha_pe?m_density tha_pe?r_en_eflux'

;

trange=['07-11-07/11:00','07-11-07/11:30']

thm_part_getspec, probe=['a'], trange=trange, angle='gyro', $

pitch=[45,135], other_dim='mPhism', $

; /normalize, $

data_type=['peir'], regrid=[32,16]

tplot,'tha_peir_an_eflux_gyro tha_fgs_gsm tha_pxxm_pot tha_pe?m_density tha_pe?r_en_eflux'

Remote sensing of wavesin ESA data, at the mostappropriate coordinateSystem, I.e, field alignedcoordinates. gyro=0o => Earthward particles



trange=['07-11-07/11:00','07-11-07/11:30']

thm_part_getspec, probe=['a'], trange=trange, angle='gyro', $

pitch=[45,135], other_dim='mPhism', $

/normalize, $

data_type=['peir'], regrid=[32,16]

tplot,'tha_peir_an_eflux_gyro tha_fgs_gsm tha_pxxm_pot tha_pe?m_density tha_pe?r_en_eflux'

Same as before but using keyword: /normalizeI.e., anisotropy is normalized to 1, to ensure flux variations do not affect anisotropy calculation.

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