Design and Testing of 1 kW Hall Thruster
Design and Testing of 1 kW Hall Thruster
Nicholas Ian Denning, Nicholas Alfred Riedel
Colorado State University
Advised by: Dr. Binyamin Rubin, Dr. John Williams
19 April 2008
Design and Testing of 1 kW Hall Thruster
Background
� Advantageous for low
thrust missions
� Currently used for
station keeping, orbit
adjustments, and deep
space missions
� High specific impulse
Denning 2
Courtesy of ESA
Design and Testing of 1 kW Hall Thruster
Hall Thruster Operation
� Electrons trapped by
induced magnetic field
(Hall Effect)
� Electron/propellant
collisions cause ionization
� Propellant ions accelerate
out of thruster
� Ions are then neutralized
Denning 3
Courtesy of www.al.t.u-tokyo.ac.jp
Design and Testing of 1 kW Hall Thruster
Hall Current Measurement
� Hall current characterization
method proposed by Rubin,
Gelman, and Kapulkin in
2008
� Embedded sensors monitor
magnetic field induced by
current loop
� Hall current measurement
used to predict thrust
Denning 4
Courtesy of Dr. Binyamin Rubin
Design and Testing of 1 kW Hall Thruster
Problem Statement
� Design and test a 1 kW Hall thruster to be used for
validation of the noncontact measurement method
proposed by Rubin, Gelman, and Kapulkin in 2008
� Two additional teams worked concurrently on remaining
components required
� Thrust Stand
� Sensor Array
Denning 5
Design and Testing of 1 kW Hall Thruster
Thruster Design
� Easily modified
� Accommodating to
sensor placement
Denning 6
Design and Testing of 1 kW Hall Thruster
Dimensioning
Denning 7
� Sizing convention from
Russian Hall thruster
designers as presented at
MIT in 1991
� Discharge chamber
diameter of 100 mm was
chosen to give
approximately 1 kW
power output.
Source: http://www.engin.umich.edu/dept/aero/spacelab/pdf/1999_gulczinski_thesis.pdf
Design and Testing of 1 kW Hall Thruster
Discharge Chamber
� Multiple plate design to
accommodate sensor
placement
� Compression plates
required to hold plates
in place
Denning 8
Design and Testing of 1 kW Hall Thruster
Anode
� Spacers incorporated to
vary anode height
� Allowed for fine tuning
of thruster output
Denning 9
Design and Testing of 1 kW Hall Thruster
Thruster Cross-Section
Denning 10
Design and Testing of 1 kW Hall Thruster
Thermal Analysis
� Steady state thermal modeling of the thruster was
performed in ePhysics
� Model was fit to match results published by
previous Hall thruster researchers
Denning 11
Design and Testing of 1 kW Hall Thruster
Magnetic Analysis
� Design analysis was
performed using Finite
Element Method
Magnetics (FEMM)
� Effects from coil current
and shields height
variations quickly
calculated
Denning 12
Design and Testing of 1 kW Hall Thruster
Magnetic Analysis continued
Denning 13
Design and Testing of 1 kW Hall Thruster
Magnetic Analysis continued
� Maxwell 3D magnetic modeling verified FEMM
resultsDenning 14
Design and Testing of 1 kW Hall Thruster
Magnetic Field Mapping
� Magnetic field mapped using two axis stage and
Gauss meter
Denning 15
Design and Testing of 1 kW Hall Thruster
Equipment
� Steel vacuum chamber ( 5 ft. diameter , 15 ft. in length) to simulate space vacuum
� Pumps: Edwards GV250 dry mechanical pump, Edwards EH-1200 mechanical booster pump, and two Varian HS-20 diffusion pumps (35,000 l/s pumping speed for air)
� Baseline pressure in the high 10-6 Torr range (10-5 range during thruster operation)
Denning 16
Design and Testing of 1 kW Hall Thruster
Denning 17
Equipment continued
Design and Testing of 1 kW Hall Thruster
Testing
Denning 18
Design and Testing of 1 kW Hall Thruster
Results
� The thruster demonstrated steady operation in the
following modes operating on argon
Denning 19
Cathode Flow Rate
(sccm)
Anode Flow Rate
(sccm)
Discharge Voltage
(V)
Discharge Current
(A)
Discharge Power (W)
5 55 154 2.02 311
5 60 146 2.79 407
5 100 125 4.95 618
Design and Testing of 1 kW Hall Thruster
Thermocouple Placements
Denning 20
Design and Testing of 1 kW Hall Thruster
Thermal Measurements
Thruster Operating Temperature
0
20
40
60
80
100
120
140
160
0 25 50 75 100 125 150 175 200 225 250
Thruster Firing Time (min)
Tem
pra
ture
(°C
)
Base Plate
Thrust Stand
Outer Coil
Outer Pole Piece
Outer Shield
Denning 21
Design and Testing of 1 kW Hall Thruster
Problems Encountered
� Magnetic core saturation
Denning 22
1 2 3 4 5 6 7 8 9 100
20
40
60
80
100
120
Axial coordinate,cm
Br,
ga
uss
inner coil - 0.5A, outer coil - 1 A
inner coil - 0.5A, outer coil - 2 A
inner coil -1A, outer coil - 1 A
inner coil - 1A, outer coil - 2 A
inner coil - 1A, outer coil - 3 A
inner coil - 1.5A, outer coil - 2 A
inner coil - 1.5A, outer coil - 3 A
Anodelocation
Exitplane
Courtesy of www.allaboutcircuits.com
Design and Testing of 1 kW Hall Thruster
Problems Encountered
� Remaining magnet field
(remanence) inhibited
thruster restart
� Procedure implemented
to reverse field
Denning 23
Courtesy of hyperphysics.phy-astr.gsu.edu
Design and Testing of 1 kW Hall Thruster
Problems Encountered
� Conductive layer built
up on discharge
chamber
� Caused anode to short
� Prevented thruster
restart
Denning 24
Design and Testing of 1 kW Hall Thruster
Future Work
� Improve the strength of the magnetic field
(thicker central core, better magnetic material)
� Fine tuning of anode height
� Complete accurate thermal map
� Integration of sensors
Denning 25
Design and Testing of 1 kW Hall Thruster
Questions
Denning 26
Design and Testing of 1 kW Hall Thruster
Conventional Ion Thrusters
� Ions accelerated through
grids
� Space charge limited
� Ion current density
restricted
� Thrust restricted
Denning 27
Courtesy of NASA
Design and Testing of 1 kW Hall Thruster
Hall Thruster Advantage
� Formation of quasi-
neutral plasma
� Not space charge
limited
� Higher thrust to weight
ratio
Denning 28
Courtesy of Drexel University