Energy Conversion & Loss Processes of Heavy gas FRCsHeavy-gas FRCs
D J h L RDr. Joshua L. RoveyAssistant Professor of Aerospace EngineeringMi i U i it f S i & T h lMissouri University of Science & Technology
(formerly University of Missouri-Rolla)
Presented to:AFOSR Contractors Meeting, Arlington, VA
May 12th, 2010
Project Main Focus
M i F Pl id f ti h i i h
Plasmoid Propelled Spacecraft
• Main Focus: Plasmoid formation physics in heavy gases– What are the collisional, radiative, transport properties during
formation of heavy-gas plasmoids?formation of heavy gas plasmoids?– How do they evolve during formation?– What are the major loss mechanisms, limiting ion production?– Methods or design features to reduce losses?
Motivation
• Higher Power Thruster10’s 100’s of kW– 10 s – 100 s of kW
– We have the technology– Costs mass
100
1000
10 MW
• Lower Specific Alpha0 1
1
10
Thru
st (N
) 1 MW
HET Ion100 kW
Plasmoid Thruster
– less kg mass per unit power
0 001
0.01
0.1T
1 kW
Ion10 kW
0.1 kWP 0.001
1032 3 4 5 6 7
1042 3 4 5 6 7
105
Specific Impulse (sec)
jet
input
PP
input jet ionization therm lossP P P P P
Plan of Attack
1. Design & develop a device that repeatably forms heavy-gas plasmoidsy g p
– No need for expulsion– Cylindrical theta pinch geometry
2 Characteri e sing time resol ed diagnostics2. Characterize using time-resolved diagnostics– Standard diagnostics: triple probe, Bdot, flux loops, wall
probes– Fast spectroscopy & bolometry (total radiation loss)– Radial & axial plasma properties
3. Develop plasma modeling to elucidate experimental3. Develop plasma modeling to elucidate experimental results, understand heavy-gas plasmoid formation physics
Dynamic plasma circuit modeling– Dynamic plasma-circuit modeling– MOQUI baseline platform– Collisions & two-fluid effects need to be included
Plasmoid Propulsion Project
• Present– LRC circuit modeling– Dynamic LRC circuit modeling– Missouri Plasmoid Experiment (MPX) design
• Future– Focus on plasmoid formation physics in heavy
gases, argon, xenon, air– Experimental test article MPX– Modeling with coupled plasma-circuit modelg p p
Dynamic Circuit Modeling
• Cylindrical coil primaryC i l l
CoilR• Concentric plasma slug• Coil and slug connected via
t l i d t
Plasma slug
mutual inductance• Electrical circuit soln.
Z
LE RE I 2ft
V C
LE RE
RSLC LSIC
IS
M
2
021
2
s sI R
CV
Primary Coil Circuit Plasma2
Initial Results – Static
• ConstantM t l i d t
0.7
γs
0.01– Mutual inductance– Slug self inductance– Slug resistance
0.4
0.5
0.6
η
0.010.020.050.10.2– Slug resistance
0
0.1
0.2
0.30.20.5
0.8 γc
0.0110
−210
−110
010
10
γc
0.4
0.6
η
0.010.020.050.10.2
0.2
0.4η 0.20.5
o Ec
C
t RL
o Ss
S
t RL
10−3
10−2
10−1
100
0γs
C S
Dynamic Plasma-Circuit Modeling
• Couple dynamic circuit modeling with a plasma model
CoilRmodeling with a plasma model• Imperative for plasma physics
focusPlasma slug
• Sizing to maximize energy into plasma
Z
LE RE IS
R
V C RSLC LSIC
Primary Coil Circuit Plasma
MZ
Primary Coil Circuit Plasma
Dynamic Plasma-Circuit Model
• Variation of:M t l i d t l di d– Mutual inductance as plasma radius decreases
– Plasma self inductance as radius decreases
• Grover Inductance Calculations• Grover – Inductance Calculations
10
100
H)
8394 7 1 9044100.0
y = 133.69x2.062
0 1
1
10
nduc
tanc
e (y = 8394.7x1.9044
10.0
tanc
e (nH
)
L=0.30mL=0 46m
0.001
0.01
0.1M
utua
l In
0.1
1.0
0 0 05 0 1
Indu
t L=0.46m
0.0010 0.1 0.2 0.3
Inner Coil Radius (m)
0 0.05 0.1Coil Radius (m)
Plasma Model
• Snowplow Model– As plasma compressed, mass entrained– Equation of motion includes pressure and magnetic force
Magnetic force d e to changing ind ctance both M and L– Magnetic force due to changing inductance, both M and L– Initial assumption, adiabatic compression
d d 2magd drm f p rdt dt
rdW dr
rdWFmag
constpV
Future Research Plan
• Focus : Plasmoid formation processes in heavy gases
• Ionization, excitationC i h i• Compression, heating
• Radiation, transport
E t bli h d t di f h l id• Establish understanding of heavy gas plasmoid energy conversion and loss processes
• Ion production efficiency • Efficient conversion of electrical energy to
thrust; minimize Etherm and Elosses
Overall Program Approach
Plasmoid Program
Experiment Numerical Modeling
i S CMPX Test Article
Plasma Properties
PrismSPECTcollisional-radiative
MOQUI?pTriple probe MOQUI?
Emission SpectraFast spectrometer
Dynamic Circuit-Plasma ModelsFast spectrometer
Total Radiation FluxPhotodiodes
Plasma Models
APLab Research Program Goal:Determine the major formation
Plasma TransportElectrostatic wall probes
physics for heavy gas plasmoids and the main loss mechanisms
Missouri Plasmoid ExperimentTest ArticleTest Article
Plasmoid Test Article
• Quartz vacuum tube connected to main vacuum chamber• Cylindrical theta pinch• High-frequency pre-ionization• Heavy-gas, xenon & argon operation• Wall probes, fast spectrometer
Fast Spectroscopy
40
60
0
20ur
rent
(kA
)
-60
-40
-20Cu
600 1 2 3
Time (microsec)3500 9000
100015002000250030003500
Inte
nsity
(-)
50010001500200025003000
Inte
nsity
(-)
2000300040005000600070008000
Inte
nsity
(-)
0500
200 400 600 800 1000Wavelength (nm)
0200 400 600 800 1000
Wavelength (nm)0
10002000
200 400 600 800 1000Wavelength (nm)
Plasma Properties versus Time
• PrismSPECTC lli i l di ti d 6000
700080009000
)
n, Te– Collisional-radiative code– LTE and non-LTE plasma– Input density/temperature 1000
20003000400050006000
Inte
nsity
(-)
– Input density/temperature– Output spectral emission
30003500
01000
200 400 600 800 1000Wavelength (nm)
3500Does not agree
1500200025003000
tens
ity(-
)
2000250030003500
nsity
(-) n, Te
Agrees
g
0500
1000
200 400 600 800 1000
Int
0500
10001500
Inte
n
200 400 600 800 1000Wavelength (nm)
Data PrismSPECT Results
200 400 600 800 1000Wavelength (nm)
Radial Plasma Properties
• Chordwise measurementsSpectrometer– Spectrometer
– Photodiode/bolometer• Analysis of spectra using y p g
PrismSPECT• Abel inversion technique
l i di l filanalysis – radial profiles• Symmetry? Radial
variation using topvariation using top chords agree with bottom?
Timeline
• Year 1 – device design, setup, operation with standard probes• Year 2 spectroscopy techniques & analysis development• Year 2 – spectroscopy techniques & analysis development• Year 3 – data comparison with models, effects of heavy gas
through comparison with hydrogeng p y g2010 2011
TASK Q2 Q3 Q4 Q1 Q2 Q3 Q4Vacuum Facility Fabrication
l d lDynamic Circuit MHD Plasma Modeling 1MPX Design FinalizedMPX Fabrication/InstallationTriple Probe/Flux Loops InstallationMPXOperational/Preliminary DataMPX Operational/Preliminary DataComparison with Modeling 1Spectroscopy DevelopmentSpectroscopy InstallationSpectroscopyMeasurementsSpectroscopy MeasurementsSpectroscopy Analysis w/ Abel InversionComparison with PrismSPECT
Vacuum Facility
Vacuum Facility
Vacuum Facility
Thank you!
• Mitat Birkan – AFOSR
• Jean-Luc Cambier, Dan Brown, Carrie Niemela –AFRL Ed dAFRL Edwards
h ill i i hl• Shawn Miller, Brian Donius, Ryan Pahl, Warner Meeks – APLab students
• Ken Schmid, Bob Hribar, Joe Boze – Missouri S&T TechniciansTechnicians
Questions?
