International Journal of Engineering Trends and Technology (IJETT) – Volume 28 Number 3 - October 2015
High Power Electric Propulsion
Rupesh Aggarwal1, Khushin Lakhara2, Prof. (Dr.) P.B. Sharma3, Tocky Darang4
1
Teaching Assistant, Department of Aerospace, Amity University Haryana, India
2,4
Student, Department of Aerospace, Amity University Haryana, India
3
PhD (Birmingham) FIE, FAeroS, FWAPS, Vice Chancellor, Amity University Haryana, India
Abstract—Present Study is the review of variation of
Ion Thruster which was designed to be used in Jupiter
Icy Moons Orbiter. Such kind of Thruster could
produce 670 mN of thrust on a Power of 39.3 KW with
a mass rate flow of 7.0 mg/s with giving the specific
impulse of 9620s.
walls to minimise wall [4], a highly efficient technique
of plasma production in low density gases.[5]
Keywords —Electric Propulsion, Ion Thruster,
Electron Cyclotron Resonance, HiPEP, Jupiter Icy
Moons Orbiter.
I. INTRODUCTION
State of art chemical propulsion technology is
disable to deal with deep space exploration due to its
lower specific impulse and huge mass problems. But
the developments in electric propulsion techniques
have expedited the increments in the area of deep
space exploration. In spite of the technological
limitations and need for the state-of-the-art
metallurgical aspects, electric propulsion systems
seemed to a promising solution with its high specific
impulse. But the problems of huge mass of electric
power production system, erosion, lesser lifetime then
requirement appears as a big obstacle in realization of
the deep interplanetary projectiles dream. But the
recent initiatives by Glenn research centre solved the
problem with high power nuclear electric propulsion
concept. The concept proved as promising solution for
higher specific impulse of range 8000s-9000s and
delta V requirements for missions with lifetime of 714 years, like Jupiter icy moon orbiter missions.[1-2]
The present paper deals with review on HiPEP
concept.
II. HIPEP OPERATING PRINCIPLE
Unlike ion thrusters, HiPEP thrusters utilizes
microwave electron cyclotron resonance (MECR)
concept, Depicted in figure 1[3], in presence of
magnetic field for electron heating. The MECR
concept establish resonance between injected
microwave frequency and gyro frequency (frequency
of rotation of an electron in magnetic field), results in
continuous gain of energy by electrons, one of the
foremost advantage of type of MECR concept. This
overall resonance process take place on the surface of
magnetic field established by magnetic circuits. Then
high energised heated electron ionizes the propellant,
a neutral gas, and generates electrodeless plasma. This
process takes place away from discharge chamber
ISSN: 2231-5381
Fig 1. Conceptual representation of resonance
heating
III. SYSTEM COMPONENTS
System or components for a HiPEPcan be classified
into following 5 categories:
A. Plasma Production:
The new MECR concept, viable plasma generation
technique implicates the replacement of the hollow
cathode convention with an electrodeless plasma
production. [6-10] The MECR technique was
investigated as an approach to eradicate the potential
discharge cathode failure mechanisms. Indeed, Plasma
potential allied with MECR are remarkably reduced in
compare to traditional hollow cathode technique. [6]
In this concern, sputtering of the upstream surface of
the screen grid can be essentially eradicate as the ions
will assault the grid at energies allied with bohm speed.
The execution of the MECR technique employs the
use of a slotted antenna, affords the opportunity for
distributed plasma production, yields uniform plasma
density profiles at the optics exit plane, resulting in
very flat beam profiles, desirable to bypass issues such
as a reduced purveyance limit and accelerated,
localized accelerator grid wear on centreline. [5-6].
The recommended source for microwave energy
production is Klystron, with lifetime of order of space
qualified tubes similar to traveling wave tube (TWT).
TWTs have already exhibited on orbit lifespan of
144K hours.[11-13] The thruster with large extraction
area is illustrated is shown in figure 2. The large ion
extraction area permits the thruster discharge chamber
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International Journal of Engineering Trends and Technology (IJETT) – Volume 28 Number 3 - October 2015
to function with reduced current density compare to
state of art thruster, reduces grid wear rates[14-15].
become worst as the unsupported span increases in
length. Indeed, the baseline grid geometry furnishes a
100 kg/kW throughput with margin at both the 8000 s
and 6000 s specific impulse design points. [18]
E. Neutralizer
Hollow Cathode Neutralizer(HCN), used in ion
thruster, addresses erosion issues allied with physical
sputtering. So instead of using HCN Microwave
Neutralizers (MN) are developed by Glen Research
Centre [4], and successfully used in deep space
mission. [19-20]. MCN is basically a plasma cathode,
neutralization concept is illustrated in figure
3.Electrons, extricated from the boundary of a very
Fig 2. Conceptual design of Thruster Pod
dense discharge plasma [21], generates number of
other electrons by collisions with gas departing the
B. Magnetic Circuit
For HiPEP thrusters ring cusp magnetic circuit neutralizer. So formed plasma bridge weakens
electron guidance policy is identified very efficient. [5] impedance, shrinks the neutralizer extraction voltage.
In the HiPEP thruster regard, magnetic rings shape Alliance of microwave neutralizer and microwave
spans from circular to hybrid circular-rectangular to main discharge plasma generator in addition to furnish
rectangular, essential to furnish the discharge chamber enhanced life, also simplifies power supply and feed
shape, made of non-ferrous steel. The magnetic circuit system essentials and eliminates gas cleanliness
design furnishes the large volume plasma generation protocols. [22-23]Both slotted antenna and internal
antenna Techniques are worthwhile alternatives for
essential for thruster operation at the design goal.
neutralizer plasma generation, actively pursued in
HiPEP concept.
C. Discharge Chamber
The thruster discharge chamber's ability to raise in
size to furnish higher power operation is a vital
thruster characteristic, addresses the flexibility to
accommodate variation with change in mission
essentials, allows the engine to be suitable to a range
of missions requiring varying power levels.[16-17]
The rectangular shape of discharge chamber
accommodates noteworthy increment in cross
sectional area by increment in lateral dimension,
accommodates discharge plasma to experience
essentially same magnetic field throughout. [4]
D. Ion Extraction Electrodes
Similar to discharge chamber, the ion optics
electrodes are also of rectangular geometry. The 2grid ion extrication system is manufactured from flat
pyrolytic graphite sheet, having remarkably lower
sputter yield at relevant energies compare to
molybdenum, used for conventional thrusters. [3]
Moreover, the grids are of large in cross-section area,
permits reduction in beam current density, and
subsidizes to reduced charge exchange erosion
rates.To increase the beam extrication area of a
traditional circular thruster, the ion aperture diameter
must increase correspondingly increment in grid span
to gap ratio, resulting in a more complex mechanical
design.Ion beam extraction area can be increased
remarkably by corresponding increment in thruster
length, but the grid gap remains closely controlled
across its width. The abovementioned aperture
attributes give the HiPEP thruster significant life
margin. With increasing length of unsupported beam
deformation due to various factors such as thermal
strain, launch vibration, and electrostatic attraction,
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Fig 3. Plasma Cathode Electron Source
IV. FACTORS INFLUENCING THRUSTER LIFETIME
Thruster lifetime is greatly influenced by following
five potential failure modes: 1. Electron back
streaming, 2. Structural failure of ion extraction
gridsdue to erosion 3. Neutralizer cathode failure 4.
Formation of an unalterable shorts between grids 5.
Discharge cathode failure. [4]
Electron back streaming takes place when erosion
widens accelerator grid aperture. As soon as aperture
remarkably widened, positive potential linked with
screen grid leak downstream of the ion optic assembly
resulting electrons from beam plasma backstream into
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International Journal of Engineering Trends and Technology (IJETT) – Volume 28 Number 3 - October 2015
the engine at potential of beam, damaging cathode by
overheating. [13]
Second failure mode is related with serious grid
erosion, takes place by charge exchange erosion. In
case beam lets are not focused well, direct
encroachment can feature erosion. Time and again
these over milling processes results in structural
poverty of the ion optic assembly and so on poorer
discharge performance and finally resulting in
cantilevering of one electrode into another terminating
beam extraction. One of the best solution for the
considered problem is magnetic grid. [10] Ion optics
lifetime can be increased by using Carbon [27-28] or
Titanium [28-29] as electrode material or by
increasing electrode thickness. [30]
Formation of unclear able shorts between grids is a
severe failure mechanism. If conducting flake
formation, formed either due to ion optic electrode
erosion or due to discharge cathode assembly erosion,
were to span the clearance between the high voltage
ion optics, resulting short can abort beam
elicitation.[30] On another grid shorting mechanism is
mattered by unattached debris from spacecraft
surfaces sorting the grids, greatest probability during
launch of spacecraft.
Cathode failure is multi aspect mechanism, in which
keeper assembly erosion and heater failure can finally
result in component failure.[32] This failure mode can
be roughly classified in two fields: emitter element
deficiency of low work function material and physical
erosion due to sputtering. Emitter failure is associated
to thermo-chemical process, that exhibit incapability
of cathode to emit electrons in the unobjectionable
pressure and thermal environment conditions. Usually
emitter failure take place after a long operation time
due to deficiency of reducing work function
depressing permeate at the emission. High temperature
also deficience sites pore-plugging compounds,
remarkably reduces work function results in lifetime
reduction. Cathode assembly features sputter erosion
due to constant expose to ion bombardment from
surrounding discharge plasma.
Elementary failure modes of the thruster are allied
with deterioration of aperture and discharge cathode.
To increase the lifetime HiPEP attitude essentially
pinpoints on remarkable excellence in the modernised
ion thruster component technology and to eliminate all
failure modes.
V. CONCLUSIONS
HiPEP system is basically developed under a
thinking of creating new propulsion system which
could satisfy the requirements for Nuclear Electric
Propulsion (NEP) missions. It has even been designed,
fabricated & ground-tested by NASA. The
Technologies introduced are integrated in such a
manner so that it could aim at increasing life of the
propulsion system. 0.75 efficiency values has been
ISSN: 2231-5381
measured on the power scale of 20-40 KW. This could
be the future of Space Propulsion.
REFERENCES
Polk, J.E, et al, ―An Overview of the NEXIS Program,‖
AIAA Paper 2003-4713, July 2003.
[2]
Patterson, M.J., Foster, J.E., Haag, T., Soulas, G.C., Pastel,
M.R., and Roman, R.F.,―NEXT: NASA’s Evolutionary
Xenon Thruster Development Status,‖ AIAA Paper 20034862, July 2003.
[3]
Three-Dimensional Particle Simulations of Ion-Optics
Plasma Flow and Grid Erosion,Joseph Wang, James Polk,
John Brophy, and Ira Katz, Journal of Propulsion and Power,
November, Vol. 19, No. 6 : pp. 1192-1199
[4]
―The High Power Electric Propulsion (HiPEP) Ion Thruster‖,
John E. Foster, Tom Haag, and Michael Patterson, George J.
Williams Jr, .James S. Sovey,Christian Carpenter, Hani
Kamhawi, Shane Malone, and Fred Elliot, AIAA–2004–3812
[5]
Sovey, J.S., ―Improved Ion Containment using a Ring-Cusp
Ion Thruster,‖ Journal of Spacecraft and Rockets, Vol. 21,
[6]
Sept.-Oct. 1984, pp. 488-495Foster, J.E. and Patterson, M.J.,
―Discharge Characterization of 40 cm-Microwave ECR Ion
Source and Neutralizer,‖ AIAAPaper 2002– 5012, July 2002.
[7]
Divergilio, W.F., Goede, H., and Fosnight, V.V., ―High
Frequency Plasma Generators,‖ NASA CR-167957,
November 1981.
[8]
Toki, H., Fujita, H., Nishiyama, K., Hitoshi, K., and Funaki,
I., ―Performance Test of Various Discharge Configurations
for ECR Discharge Ion Thruster,‖ IEPC Paper 01-107,
October 2001.
[9]
Kuninaka, H., Satori, S., Funaki, I., Shimizu, Y., and Toki,
K., ―Endurance Test of Microwave Discharge Ion Thruster
System for Asteroid Sample Return Mission MUSES-C,‖
IEPC Paper 92-137, December 1997.
[10] Toki, K., et al., ―Technological Readiness of Microwave Ion
Engine System for MUSES-C Mission,‖ IEPC 01-174,
October 2001.
[11] Park, S.S. et al., ―Reliability Analysis of Klystron-Modulator
System,‖
Proceedings
of
the
Second
Asian
ParticleAccelerator Conference, Beijing, China, 2001.
[12] Hansen, J.W., ―US TWTs from 1 to 100 GHz,‖ Microwave
Journal, 1989, Vol. 32, pp. 179-183
[13] .Dieumegard, D. et al, ―Life Test Performance of Thermionic
Cathodes,‖ Applied Surface Science, Vol. 111, February,1997,
pp. 84-89.
[14] El-Genk, M.S., ed., A Critical Review of Space Nuclear
Propulsion: 1984-1993, AIP Press, NY, 1994, pp. 22-23.
[15] Sengupta, A., et al, ―Status of the Extended Life Test of the
Deep Space 1 Flight Spare Ion Engine after 30,000 hours of
Operation,‖ AIAA paper 2003-4558, July 2003.
[16] Polk, J.E, et al, ―An Overview of the NEXIS Program,‖
AIAA Paper 2003-4713, July 2003.
[17] Patterson, M.J., Foster, J.E., Haag, T., Soulas, G.C., Pastel,
M.R., and Roman, R.F.,―NEXT: NASA’s Evolutionary
Xenon Thruster Development Status,‖ AIAA Paper 20034862, July 2003
[18] Williams, G.W. , Sovey, J., and Haag, T., ―Performance
Characterization of HiPEP Ion Optics,‖ AIAA Paper 20043627, July 2004.NASA/TM—2004-213194 12
[19] Sengupta, A., Brophy, J.R., Garner, C.E., and Anderson, J.A.,
―An Overview of the Results from the 30,000 Hour Life Test
of the Deep Space One Flight Spare Ion Engine,‖ AIAA
Paper 2004-3608, July 2004.
[20] Toki, K, Kuninaka, H., Nishiyama, K., Shimizu, Y., and
Funaki, I., ―Technological Readiness of Microwave Ion
Engine system for Muses-C mission,‖ IEPC 01-120, October
2001.
[21] Satori, S, Kuninaka, H., Ohtaki, M, and Ishikawa, Y.,
―Operational Characteristics of Microwave Discharge
Neutralizer,‖ IEPC Paper 97-05, December 1997.
[22] Oaks, E. M., ― Physics and Techniques of Plasma Electron
Sources,‖ Plasma Sources Sci. Technol., Vol. 1, 1992, pp.
249- 255.
[1]
http://www.ijettjournal.org
Page 132
International Journal of Engineering Trends and Technology (IJETT) – Volume 28 Number 3 - October 2015
[23]
[24]
[25]
[26]
[27]
[28]
Kamhawi, H., Foster, J., and Patterson, M.J., ―Parametric
investigation of an ECR cathode,‖ AIAA Paper 2004-3819,
July 2004.
‖ElectricPropulsionLaboratory:Facility
Capabilities,‖
http://facilities.grc.nasa.gov/epl/epl_caps.html.
Soulas, G.C., Domonkos, M.T., and Patterson, M.J.,
―Performance Evaluation of the NEXT Ion Engine
Soulas, G.C., Foster, J.E., and Patterson, M.J., ―Performance
of Titanium Optics on a NASA 30 cm Ion Thruster,‖ AIAA
Paper 2000-3814, July 2000.
Shotwell, R., ―Carbon-Carbon Grid Development for Ion
Propulsion Systems,‖ IEPC Paper 2001-093, October 2001.
Haag, T., Patterson, M.J., and Soulas, G.C., ―Carbon-Based
Ion Optics Development at NASA GRC,‖ IEPC Paper 2001094, October 2001.
ISSN: 2231-5381
[29]
[30]
[31]
[32]
Soulas, G.C., ―Improving Total Impulse Capability of the
NSTAR Ion Thruster with Thick-Accelerator –Grid Ion
Optics,IEPC Paper 01-081, October 2001.
Sengupta, A., Brophy, J.R., Garner, C.E., and Anderson, J.A.,
―An Overview of the Results from the 30,000 Hour Life
Testof the Deep Space One Flight Spare Ion Engine,‖ AIAA
Paper 2004-3608, July 2004.
Polk, J.E, et al, ―An Overview of the NEXIS Program,‖
AIAA Paper 2003-4713, July 2003.
Patterson, M.J., Foster, J.E., Haag, T., Soulas, G.C., Pastel,
M.R., and Roman, R.F.,―NEXT: NASA’s Evolutionary
Xenon Thruster Development Status,‖ AIAA Paper 20034862, July 2003.
http://www.ijettjournal.org
Page 133