Space Environment and Satellite Systems

Transient Plasma Analyzerfor Hypervelocity Impact Studies

Dr. David LaubenJanuary 9, 2013

IntroductionTransient Plasma Analyzer (TPA)• Characterize transient low-energy plasma plume• Every shot unique: no event repetition, no control• Make THIN! (< 5mm) to allow side-panel mount

2

(4) lower plasmadiagnostic panels

(4) upper plasmadiagnostic panels

7cm

5cm

target

ejecta

μg

flash

plasma

photo-diodes

(4) lower plasmadiagnostic panels

(4) upper plasmadiagnostic panels

7cm

5cm

target

ejecta

μg

flash

plasma

photo-diodes

Early Concept (Deployable Target)Simplified Concept (Solar Panel Targets)

Build on previous success!

3

-+

RPA GroundedBNC

Vacuum Air

n/c

Vout

Vcom

V+Scope

V-

±100V

±50V

-10V

Vrep

Vthr

Vsup

D. Lauben, 2010-Aug-03

RPA’s share vacuum-side voltage as follows:1.Like charge species share Vrep, Vsup2.Like charge species may share Vthr3.All RPA’s share V+ and V- power

FloatedSMA

Wall

-+

RPA GroundedBNC

Vacuum Air

n/cn/c

Vout

Vcom

V+Scope

V-

±100V

±50V

-10V

Vrep

Vthr

Vsup

D. Lauben, 2010-Aug-03

RPA’s share vacuum-side voltage as follows:1.Like charge species share Vrep, Vsup2.Like charge species may share Vthr3.All RPA’s share V+ and V- power

FloatedSMA

Wall

• Simple Retarding Potential Analyzer• Concept to working unit in < 30 days• 1st unit fab: ~3 days; 2nd unit: 1 day!

Introduction• Initial Concept (c.f. Enloe et al., 2003)

4

-3 -2 -1 0 1 2 3

-2

-1

0

1

2

Electron Trajectories, Vbias = -275 V

mm

mm

10 15 20 25 30 350

10

20

30

40

50

60

Energy (eV)

Cou

nts

Energy Passband (20 eV)

-3 -2 -1 0 1 2 3

-2

-1

0

1

2

Electron Trajectories, Vbias = -275 V

mm

mm

E > Ehi

En < Elo

collector

entranceaperture

Elo < E < Ehi

Improvement• Revised “C” Aperture (best efficiency)

5

(comsol model)

3D Trajectory Simulation• Accepted particles

6

3D Trajectory Simulation• Rejected particles

7

low energies reflect high energies miss collector

^ isolation shieldneeded here

Response vs Energy, Angle

8

normal incidence

non-ideal,but accept

Fabrication• “All PCB” design (4 layer + 2 layer)

93D rendering from PCB cad package

Cu (Gnd)

Cu (Gnd)

Prepreg

Prepreg

Core

Core

Core

Cu (Gnd)Prepreg

Cu (Gnd)

Cu (Bias) Cu (Bias)

Cu (Collector pad)

Prepreg

Cu (for mounting components)

PCB stack-up, confirmed w/supplier

TPA Design Summary• “All PCB” flat-panel Transient Plasma Analyzer

• c.f., AFIT: MESA, iMESA (ISS/MISSE-7), PCBSAT

• 12x12 mm-scale micro-electrostatic analyzers• (8) clusters of 9 cells/cluster, for (8) e- energy bands• (8) clusters of 9 cells/cluster, for (8) ion energy bands

• Commandable bias voltage for energy selection• Ex: unbiased target: V = 0.5, 1, 2, 5, 10, 20, 50, 100+• Ex: biased target: V = 5, 10, 20, 50, 100, 200, 500+

• Option (at fabrication) for extreme bandwidth• Default: BW > 10 MHz using standard COTS electronics• Option: BW > 1 GHz using latest UWB high-fT discretes

• Data as raw, or onset + time-over-threshold mode10

TPA Development Plan

11

• Ground Tests (Stanford)• Calibrate using standard low-energy e-, ion sources• Simulate HVI events via nanosecond, microjoule laser• Plasma production, RF emission, Sensor Response

• Ground HVI Experiments (LASP)• Measure hypervelocity (>20 km/s), femtogram projectiles• Verify computer models: Plasma, RF, Chamber, Sensors

• Prototype Test Flight• Low-earth orbit plasma environment

• Science Missions!• True in-situ micrometeoroid distribton

Accurate Chamber Effects Model