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CAM200 Hall Thruster - Development Overview

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IAC-15- C4.4.4 Page 1 of 5
IAC-15-C4.4.4
CAM200 HALL THRUSTER - DEVELOPMENT OVERVIEW
Dan Lev, Raanan Eytan, Gal Alon, Abraham Warshavsky and Leonid Appel
Rafael - Advanced Defense Systems Ltd., Haifa, 3102102, Israel, Danle@Rafael.co.il
Alexander Kapulkin and Maxim Rubanovych
Asher Space Research Institute (ASRI), Technion - Israel Institute of Technology, Haifa, 3200003, Israel
We present the development campaign of the CAM200 low power Hall thruster from initial prototype
testing to current performance mapping. The development program presented included proof-of-concept
tests, experimental and theoretical validation of physical mechanisms, wall material selection, performance
and instabilities testing, thruster engineering model production and simulations as well as performance
mapping. During the development campaign CAM200 demonstrated exceptional performance with anode
specific impulse and anode efficiencies well above 1500 sec and 43% respectively at a power level of 250 W.
We also list the planned qualification program with the goal of a full qualification of the CAM200 thruster.
I. INTRODUCTION
Hall Effect Thrusters (HET) are a class of electric
thrusters commonly used for various types of satellite
manoeuvres1. Specifically, low power Hall thrusters,
thanks to their light weight, low thrust and low power
consumption may be used for many applications. For
example, microsatellite orbit injection, Low Earth Orbit
(LEO) drag compensation, E-W communication satellite
slot maintenance or LEO de-orbit manoeuvres2,3.
However, low power Hall thrusters have some
shortcomings relative to their higher power cousins. At
power levels lower than 500 watts Hall thrusters exhibit
reduced efficiency, reduced specific impulse and shorter
lifetime4. Consequently, to utilize low power Hall
thrusters their performance penalties should be
mitigated either by a suitable thruster design or by
appropriate operation technique.
The Co-axial Anode Magneto-Isolated Longitudinal
Anode (CAMILA) HET confronts low power Hall
thruster weaknesses. This is done by a combination of
an unconventional design and a unique magnetic field
pattern. The CAMILA HET incorporates co-axial
anodes, contrary to conventional HET design where the
gas distributer is also the anode. The co-axial anode
structure assists in forming equipotential lines parallel
to the thruster walls; therefore repelling incoming ions
and increasing propellant efficiency relative to
conventional Hall thrusters5,6. In addition, a specific
class of the CAMILA thruster, denoted Full-CAMILA,
contains two internal magnetic coils that generate
magnetic field pattern parallel to the anode surface to
focus the ions at the center of the thruster cavity7,8.
The CAMILA Hall thruster was developed at the
Asher Space Research Institute (ASRI) at the Technion
in cooperation with Rafael9 and initially tested at the
Soreq NRC facility. After preliminary proof-of-concept
set of tests on the CAMILA thruster prototype thruster
development moved to Rafael with the purpose of
improving some engineering aspects of the thruster and
designing a flight-ready model.
II. DEVELOPMENT CAMPAIGN
CAM200 development program is presented in Fig.
1. The development program commenced with the
design, manufacture and experimental investigation of
the CAMILA prototype and currently is in the midst of
a full thruster performance mapping. An elaborated
description of each of the development stages is
presented hereafter.
Thruster Physics
Numerical
Analysis
Ceramic Wall
Material
Selection
Performance
Testing
Prototype
Experimentation
Thruster
Instabilities Test
Structural,
Magnetic and
Thermal Analyses
Electrical
Configuration
Test
Performance
Mapping Present Time
Fig. 1 : CAM200 development program
Prototype Experimentation
Laboratory prototype of the CAMILA Hall thruster
(Fig. 2) was designed, manufactured and experimentally
tested6,9,10. During the initial proof-of-concept
experimental investigation two configurations of the
CAMILA thruster were explored - the Full-CAMILA
and the Simplified-CAMILA. Each thruster
configuration consists of co-axial anodes yet the
magnetic pattern is different as described above. All
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IAC-15- C4.4.4 Page 2 of 5
configurations of the CAMILA thruster were designed
to operate in the 100 W to 300 W power range.
During the initial experimental campaign the
CAMILA Hall thruster demonstrated exceptional
performance with efficiency higher than 0.5 and specific
impulse higher than 1500 sec at power levels lower than
250 W. These performance values are the highest ever
recorded for very low power Hall thrusters.
Additionally, Langmuir probe measurements of the
plasma properties inside the thruster were conducted to
explain the CAMILA thruster's high performance11,12.
The measurements confirmed high ion density in the
channel center, leading to an efficient propellant
ionization and low ion-to-wall loses.
Fig. 2: Schematic of the CAMILA Hall thruster
prototype9.
1 Anode; 2 Gas distributor; 3 Magnetic circuit; 4
Central magnetic coil; 5 Inner anode coil; 6 Anode
cavity; 7 - Magnetic screens; 8 Acceleration channel;
9 Cathode-neutralizer; 10 Outer anode magnetic
coils; 11 - Outer magnetic coils.
Thruster Physics Numerical Analysis
Particle in Cell (PIC) simulations of the CAMILA
thruster and its configurations were conducted to better
understand the physical mechanisms behind the
CAMILA Hall thruster performance. The results
obtained from the simulation confirmed the reasons for
the high performance demonstrated and were in
accordance with the experimental measurements.
Example showing the high density in the thruster cavity
is presented in Fig. 3.
Fig. 3: Simplified CAMILA: spatial distribution of
plasma density contours - color coded log scale, m3.
White lines are magnetic field lines7.
Ceramic Wall Material Selection
After initial validation further thruster development
was conducted at Rafael with the continuous support of
ASRI13. Subsequently a Development Model (DM) also
denoted CAM200-DM was designed, manufactured and
tested. CAM200-DM incorporated engineering
improvements compared with the CAMILA thruster.
For example, improved ceramic insulation, the use of
additive layer manufacturing (3-D printing) for the
reduction of cost and manufacture duration as well as
the development of production processes.
An experimental program was conducted to identify
the most suitable ceramic wall material for CAM200-
DM14. The program included environmental testing such
as shock and vibration tests. The material selection
program also included performance and erosion test
comparison between the different wall materials.
The exhaustive wall material selection program
resulted in the selection of boron nitride grade M26,
also referred to as 'Borosil', as the most suitable wall
material for the CAM200 thruster.
Performance Testing
During the ceramic wall material selection process
an emphasis was given to thruster performance testing.
During the performance testing high thruster
performance was validated as observed with the
CAMILA prototype Hall thruster.
Thruster Instabilities Test
After performance testing, and as part of the Micro-
satellite Electric Propulsion System (MEPS) project2,3,
thruster impedance was measured. The thruster was
operated both in steady state and in ignition modes and
thruster instabilities recorded. It was found that the
CAM200 thruster exhibits predator-pray instability in
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IAC-15- C4.4.4 Page 3 of 5
the 10 kHz frequency range as expected of Hall
thrusters. The slightly low frequency measured for this
instability, which is typically higher in conventional
Hall thrusters15, can be explained by the fact that the
ionization region in the CAMILA-type Hall thrusters
penetrates into the anode region. The long distance
between the ionization and acceleration regions, relative
to conventional Hall thrusters, may lead to lower
instability frequencies.
Structural, Magnetic and Thermal Analyses
After the basic structure and materials of the
CAM200 thruster were determined an Engineering
Model (EM) of the thruster, denoted CAM200-EM, was
designed and manufactured (Fig. 4). In CAM200-EM
additional engineering improvements were implemented
in order for the thruster to properly withstand structural,
magnetic and thermal environmental conditions under
the European Cooperation for Space Standardization
(ECSS).
Fig. 4: Picture of CAM200-EM Hall thruster
As a result various finite element simulations were
performed to estimate the structural, magnetic and
thermal behaviour of the thruster under the expected
mission environmental conditions. Example of the CAD
and simulation models is presented in Fig. 5.
Fig. 5: CAD model and simulation model of the
CAM200-EM Hall thruster
Structural simulation results indicated structural
integrity throughout the expected structural
environmental conditions. Dedicated shock tests were
conducted to reduce fracture risk in regions susceptible
to structural constraints. All tests were successful thus
validating thruster integrity.
Thermal simulations were performed at three
thruster operational point - 100 W and exposed to open
space, 200 W nominal operation and 250 W facing the
sun. The power loads to the different parts of the
thruster were computed using a Hall thruster heat load
model that takes into consideration the thruster's
operational conditions, basic thruster structure,
measured electron temperatures at various regions of the
thruster and cathode power deposition16.
The results from the hottest expected thruster
scenario under operation at 250 W are presented in
Fig. 6. It can be observed from the thermal analysis
results that even at the most extreme case of highest
power operation while facing the sun the highest
thruster temperature is lower than 450°C. This is an
acceptable temperature for the inner ceramic channel
that can withstand much higher temperatures.
Temp’, ºC
450
350
250
100
Fig. 6: Thermal simulation results for the 250 W
anode power case while thruster is facing the sun.
Electrical Configuration Test
The experimental campaign conducted on the
prototype of the CAMILA thruster included an
electrically insulated gas distributer. However, from a
design point of view it is easier to design a thruster
configuration where the gas distributer is at anode
potential. Accordingly, both thruster electrical designs
were explored. It was shown that at the chosen magnetic
field configuration thruster performance is insensitive to
gas distributer electrical potential within measurement
error bars.
These results allow for either a simplistic electrical
insulation between the anode and gas distributer or the
complete removal of such insulation.
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IAC-15- C4.4.4 Page 4 of 5
Performance Mapping
The current state of the on-going CAM200-EM
development program includes full performance
mapping. In this development phase thruster
performance is investigated at a wide range of
operational parameters beyond the parameter range
specified in the MEPS project specification
requirements.
Some of the experimental results obtained thus far
are presented in Fig. 7 - Fig. 9.
Fig. 7: Experimental results of thrust as measured on
the CAM200-EM Hall thruster.
100 150 200 250 300
800
1000
1200
1400
1600
Pd, W
Ispa, sec
Fig. 8: Experimental results of specific impulse as
measured on the CAM200-EM Hall thruster.
100 150 200 250 300
20
25
30
35
40
45
Pd, W
a [%]
Fig. 9: Experimental results of anode efficiency as
measured on the CAM200-EM Hall thruster.
These experimental results demonstrate the
outstanding performance of the CAM200-EM thruster
with anode specific impulse and anode efficiencies well
above 1500 sec and 43% respectively at a power level
of 250 W.
Additionally, the thruster mapping effort includes
performance sensitivity to changes in magnetic field
magnitude. This check will aid in determining the
required operational point, in terms of magnetic field
magnitude, that will maintain thruster operation stability
throughout mission lifetime. Also, this check will allow
the reduction of magnetic field power to the minimal
needed to properly operate the thruster; therefore
increasing system efficiency.
III. CONCLUSIONS AND FUTURE WORK
CAM200 Hall thruster development has been
overviewed from initial prototype design to current
thruster performance mapping.
The development program presented included proof-
of-concept tests, experimental and theoretical validation
of physical mechanisms, wall material selection,
performance and instabilities testing, thruster EM
production and simulations as well as performance
mapping. This meticulous thruster development plan
ensures a reliable and robust thruster.
Further CAM200 development will be conducted as
part of the MEPS project and will include: thruster-
cathode coupling experiment, full characterization test,
shock and vibration tests, lifetime test and a full system
coupling test. The end goal of the program is to fully
qualify the CAM200 thruster and present it as a viable
solution for various types of space missions.
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IAC-15- C4.4.4 Page 5 of 5
REFERENCES
1Dan M. Goebel & Ira Katz. Fundamentals of Electric
Propulsion: Ion and Hall Thrusters. JPL Space Science and
Technology Series, Jet Propulsion Laboratory & California
Institute of Technology, 2006.
2Tommaso Misuri, Riccardo Albertoni, Cosimo Ducci,
Barak Waldvogel, Leonid Appel, Raanan Eytan, Dan Lev,
Kathe Dannemayer and Davina Di Cara. "MEPS: A Low
Power Electric Propulsion System for Small Satellites".
Proceedings of the 10th IAA Symposium on Small Satellites for
Earth Observation Berlin, Germany, April 20 - 24, 2015, IAA-
B10-1103.
3Tommaso Misuri, Mariano Andrenucci, Jacob
Herscovitz, Barak Waldvogel and Kathe Dannenmayer.
"MEPS Programme - New Horizons for Low Power Electric
Propulsion Systems". Proceedings of the 34th International
Electric Propulsion Conference (IEPC), July 4-10, 2015,
Hyogo-Kobe DC, USA, IEPC-2015-491.
4E. Ahedo and J. M. Gallardo. Scaling Down Hall
Thrusetrs. In The 28th International Electric Propulsion
Conference (IEPC), 17-21 March, 2003, Toulouse, France,
IEPC-03-104.
5A. Kapulkin and M. Guelman. "Theoretical Modeling of
Ionization Processes in Anode Cavity of CAMILA Hall
Thruster". Proceedings of the 31st International Electric
Propulsion Conference (IEPC), 20-24 September, 2009, Ann
Arbor, Michigan, USA, IEPC-2009-068.
6M. Rubanovich, V. Balabanov, A. Kapulkin and E.
Behar. "Experimental Investigations of Component
Determining CAMILA Hall Thruster Performance".
Proceedings of the 33nd International Electric Propulsion
Conference (IEPC), October 6-10, 2013, Washington DC,
USA, IEPC-2013-235.
7Kronhaus, I., “Experimental and Numerical
Investigations of the Physical Processes in a Co-Axial
Magneto-Isolated Longitudinal Anode Hall Thruster”. Ph.D.
Dissertation, Aerospace Dept., Technion - Israel Institute of
Technology, Haifa, Israel, 2012.
8Kronhaus, I., Kapulkin, A., Guelman, M., Natan, B.,
"Investigation of Two Discharge Configurations in the
CAMILA Hall Thruster by the Particle-in-Cell method",
Plasma Sources Sci. Technol., Vol. 21, p. 035005, 2012.
9M. Guelman, A. Kapulkin, V. Balabanov, L. Rabinovich,
G. Appelbaum. "A New Low-Power Hall Thruster Concept".
Proceedings of the The 59th International Astronautical
Congress, Glasgow, Scotland, 29 Sep 3 Oct 2008, IAC-08-
C.4.4.6.
10A. Kapulkin, V. Balabanov, M. Rubanovich, E. Behar,
L. Rabinovich and A. Warshavsky. "CAMILA Hall Thruster:
New Results". Proceedings of the 32nd International Electric
Propulsion Conference (IEPC), October 11-15, 2011,
Wiesbaden, Germany, IEPC-2011-041, 2011.
11Kronhaus, I., Kapulkin, A., Balabanov, V., Rubanovich,
M., Guelman, M.,Natan, B., "Investigation of Physical
Processes in CAMILA Hall Thruster using Electrical Probes",
J. Phys. D: Appl. Phys. Vol. 45, p. 175203, 2012.
12Kronhaus, I., Kapulkin, A., Balabanov, V., Rubanovich,
M., Guelman, M., Natan, B., ”Discharge Characterization of
the Coaxial Magnetoisolated Longitudinal Anode Hall
Thruster,” Journal of Propulsion and Power, Vol. 29, pp.
93849, 2013.
13Jacob Herscovitz, Zvi (Zucki) Zuckerman and Dan Lev.
"Electric Propulsion Developments at Rafael". Proceedings of
the 34th International Electric Propulsion Conference (IEPC),
July 4-10, 2015, Hyogo-Kobe DC, USA, IEPC-2015-030.
14Raanan Eytan, Dan Lev, Gal Alon, Abraham
Warshavsky, Alexander Kapulkin and Maxim Rubanovych.
"Wall Material Selection Process for CAM200 Low Power
Hall Thruster". Proceedings of the 34th International Electric
Propulsion Conference (IEPC), July 4-10, 2015, Hyogo-Kobe
DC, USA, IEPC-2015-103.
15E. Y. Choueiri, “Plasma Oscillations in Hall Thrusters,”
Phys. of Plasmas, vol. 8, no. 4, pp. 14111426, 2001.
16Lev, Dan. CAM200-EM - Power Load Model. Internal
Report, RAF#12177236-v1: Rafael. Advanced Defence
Systems Ltd. 2015. 11.
... CAM200 was developed by Rafael to serve as efficient means of propulsion for power-limited micro-satellites. 7 Moreover, CAM200 takes part in the European-Israeli Micro-satellite Electric Propulsion System (MEPS) project. 8,9 The goal of the MEPS project, which is funded by European Space Agency (ESA) and the Israeli Space Agency (ISA), is to design, manufacture and qualify an electric propulsion system for micro-satellites. ...
... Lessons learned and further improvements from CAM200 Development Model (DM) were implemented in the CAM200-EM with the purpose of producing a lighter-weight, electrically and mechanically robust thruster capable of operating in the expected environment of space. 7 In addition, an effort was made to simplify some of the manufacture procedures of the thruster; therefore making it quicker to produce and cost effective. The key features of the CAM200 thruster are listed in Table 2. ...
Conference Paper
In this paper we present two of the main activities conducted as part of the CAM200 Hall thruster development campaign at Rafael: thruster performance characterization and vibration test. We present the CAM200 thruster performance maps and emphasize the unusually high performance; i.e. thrust, Isp and efficiency (12mN, 1,550sec and 45% @200W respectively). We present the vibration test campaign in which we examined the possible effects of the maximum expected launch loads on thruster performance and structural integrity. Using resonance sweeps we show that the thruster's structural Eigen frequencies are well above the minimum allowed value of 140 Hz. Additionally, no performance degradation, due to applying launch loads, was observed. Lastly, the thruster's structural integrity was preserved throughout all vibration tests. Nomenclature I m = current to magnet coils Isp = specific impulse P d = discharge power T = thrust V d = discharge voltage ṁ = mass flow rate η = efficiency
... No difference in the thruster performance was found before and after the test. (2) Thruster axis perpendicular to mounting plane (3) Thruster axis parallel to mounting plane (4) Values computed for measured thruster weigh of 0.410 kg (including IF washers and screws) ...
... This configuration enables high performance relative to traditional Hall thrusters operating at low power. To date the thruster has undergone full scale development that included performance testing, electrical circuit configuration, environmental testing and cathode coupling test [3]. The model currently operated is an Engineering Model (EM). Figure 4-1) was designed, manufactured, integrated and initiated its testing campaign during 2014 and 2015. ...
... CAM200 was developed by Rafael to serve as efficient means of propulsion for power-limited micro-satellites. 7 Moreover, CAM200 takes part in the European-Israeli Micro-satellite Electric Propulsion System (MEPS) project. 8,9 The goal of the MEPS project, which is funded by European Space Agency (ESA) and the Israeli Space Agency (ISA), is to design, manufacture and qualify an electric propulsion system for micro-satellites. ...
... Lessons learned and further improvements from CAM200 Development Model (DM) were implemented in the CAM200-EM with the purpose of producing a lighter-weight, electrically and mechanically robust thruster capable of operating in the expected environment of space. 7 In addition, an effort was made to simplify some of the manufacture procedures of the thruster; therefore making it quicker to produce and cost effective. The key features of the CAM200 thruster are listed in Table 2. ...
... Such thrusters typically deliver 10 mN of thrust with an efficiency around 40% despite small dimensions. Currently, the most advanced devices are, to the best of our knowledge, the BHT200 American HT [18], the SPT30 and Plas-40 Russian HTs [19], [20], the CAM200 Israeli HT [21], the HT100 Italian HT [22], the KAIST Korean HT [23], and the ISCT200 French HT [24]. The inclined reader can find additional information about low-power annular HTs in [24] and [25] and references herein. ...
... Rafael's CAM200 Engineering Model (EM) (Shown in Table 1) was designed, manufactured, integrated and initiated its testing campaign during 2014 and 2015. Lessons learned and further improvements from CAM200 Development Model (DM) were implemented in the CAM200-EM with the purpose of producing a lighter-weight, electrically and mechanically robust thruster capable of operating in the expected environment of space 10 . In addition, an effort was made to simplify some of the manufacture procedures of the thruster; therefore making it quicker to produce and cost effective. ...
Conference Paper
Full-text available
CAM200 is a low power Hall thruster operating in the 100-250 W power range. We present two recent activities in the development of the CAM200 Hall thruster-performance validation in an independent facility and measurement of the ion flux in the thruster plume. We show that the thruster performance, measured throughout six different operation points, is in line with the performance recorded at the Technion in past experiments (At 250 W: Thrust of 13.9±0.6mN, Isp of 1570±73 sec and efficiency of 43±3.7%). We also present ion flux curves for each operation point and show that the beam divergence angle is less than 40° for discharge power of 160 W and higher.
... Rafael's CAM200 Engineering Model (EM) (Shown in Figure 2) was designed, manufactured, integrated and initiated its testing campaign during 2014 and 2015. Lessons learned and further improvements from CAM200 Development Model (DM) were implemented in the CAM200-EM with the purpose of producing a lighter-weight, electrically and mechanically robust thruster capable of operating in the expected environment of space 5 . In addition, an effort was made to simplify some of the manufacture procedures of the thruster; therefore making it quicker to produce and cost effective. ...
Conference Paper
Full-text available
Micro-Satellite Electric Propulsion System (MEPS) is a development and qualification programme jointly supported by the European Space Agency (ESA) and the Israeli Space Agency (ISA) aiming at the full space qualification of a low power electric propulsion system specifically designed to be used onboard for small satellites (mini-and micro-class). The system is conceived to have maximum flexibility to be appealing for a wide variety of missions, ranging from drag-compensation to spacecraft de-orbiting. To date the system components were developed to bread-board and engineering models level and take part in system integration tests. Currently Rafael and Sitael, the two prime companies that are in charge for the system development, are approaching the thruster units endurance test campaign, in parallel to power processing unit and propellant management assembly development.
... To combat this drawback of low power Hall thrusters, Rafael, in cooperation with the Asher Space Research Institute (ASRI), has developed a unique Hall thruster [ 3]. The Hall thruster, denoted CAM200, is designed to operate in the 100-300 W discharge power range and exhibits exceptionally high thrust efficiency. ...
Conference Paper
Full-text available
Using a semi-empirical power load model we estimate the various input power components, in the 100-250 W power range, in a co-axial anode Hall thruster, denoted CAM200, that is designed and manufactured by Rafael. The model shows that at low power the heat dissipated into the co-axial anodes and ceramic channel is dominant and takes up to 40% of the discharge power. However, as discharge power increases this power fraction decreases down to about 25% and the thrust generation mechanisms become more efficient. The model shows that undirected kinetic power consumes approximately 22% of the discharge power while assuming a constant divergence angle. The model also shows that both thermal power and cathode power consume a small fraction (<10% each) of the discharge power and are relatively constant with changes in discharge power. The presented power load model suffices for the calculation of the thruster unit temperature distribution, with discharge power, and can be used in the future for this purpose.
Article
Full-text available
The CAMILA (co-axial magneto-isolated longitudinal anode) concept was developed to improve the anode efficiency in low-power Hall thrusters. Previous measurements, performed in Asher Space Research Institute, have shown that the thruster has the highest efficiency for its class. This paper presents an analysis of the discharge structure in an effort to improve understanding of the physical processes in CAMILA type thrusters. Internal measurements of the discharge parameters were performed using an emissive probe, a biased probe and a Faraday cup. The probes were mounted on a positioning system capable of mapping the channel in two dimensions. Maps for the plasma potential, the ion current density and the electron temperature were obtained. In addition, a one-dimensional fluid model was developed in order to compute the distribution of the plasma density and the ion velocity. The experimental investigations confirmed the basic assumptions used in the physical model of the CAMILA concept and revealed phenomena related to the radial non-uniformity of the discharge. In particular, focusing equipotentials were discovered in the area of intense ionization, reducing ion loss to the walls of the channel. This mechanism is principal in obtaining the high efficiency of the thruster. When operated with strengthened longitudinal magnetic field, the plasma density inside the anode cavity was significantly higher in the middle than near the anodes. The fraction of ion current generated inside the anode cavity was greater than in the simplified case, 19% compared with 13% respectively. In addition, it was shown that electrons in the cusp region, the region between predominately radial to predominately axial magnetic fields, were not well confined, however, no potential hump is created and ions are able to cross this region to the acceleration channel.
Article
Full-text available
The nature of oscillations in the 1 kHz–60 MHz frequency range that have been observed during operation of Hall thrusters is quantitatively discussed. Contours of various plasma parameters measured inside the accelerating channel of a typical Hall thruster are used to evaluate the various stability criteria and dispersion relations of oscillations that are suspected to occur. A band by band up-to-date overview of the oscillations is carried out with a description of their observed behavior and a discussion of their nature and dependencies through comparison of the calculated contours to reported observations. The discussion encompasses the excitation of low frequency azimuthal drift waves that can form a rotating spoke, axially propagating “transit-time” oscillations, azimuthal drift waves, ionization instability-type waves, and wave emission peculiar to weakly ionized inhomogeneous plasmas in crossed electric and magnetic fields.
Article
The coaxial magnetoisolated longitudinal anode concept was introduced to improve efficiency and lifetime of lowpower Hall thrusters (≤350 W). The coaxial magnetoisolated longitudinal anode represents a significant departure from conventional Hall thrusters and has not been thoroughly studied yet. The high efficiency of the thruster, as validated by measurements, increases the need for a better understanding of the physical processes in this type of thruster. An analysis of the coaxial magnetoisolated longitudinal anode discharge based on experimental measurements was conducted for this aim. The experimental setup includes electrical probes mounted on a fast moving positioner, enabling one to obtain the spatial distribution of plasma parameters inside the thruster channel. The results confirmed the basic assumptions used in the physical model of the coaxial magnetoisolated longitudinal anode concept and revealed new phenomena related to the radial nonuniformity of the discharge. In particular, focusing equipotentials were discovered not only in the anode cavity but also in the dielectric channel, where the area of intense ionization was located. The physical processes contributing to the formation of the focusing equipotentials are discussed.
Article
The CAMILA (co-axial magneto-isolated longitudinal anode) concept was introduced to improve the ionization efficiency in low-power Hall thrusters. With relatively large coaxial anode surfaces and longitudinal magnetic strength, the CAMILA represents a significant departure from conventional Hall thrusters. In order to investigate the physical processes inside the CAMILA thruster, a two-dimensional particle-in-cell simulation of the thruster channel is used. The discharge parameters are analysed in two magnetic configurations: simplified CAMILA with a conventional magnetic field and full CAMILA with strengthened longitudinal component of the magnetic field. The simulation is fully kinetic with electrons, ions and gas atoms (xenon) represented as particles. Electron–neutral interactions are included together with particle–boundary interactions such as recombination and secondary emission. In addition, dielectric boundaries float and the cathode is represented as a free-space boundary, emitting electrons to satisfy quasi-neutrality on its surface. The high anode efficiency, observed in experiments, can be explained by several mechanisms found in this work. In the simplified case (magnetic configuration similar to the experiments) a focusing potential is created near the anode–dielectric boundary that directs ions away from the walls. It is created due to a combination of anode placement, in parallel with the channel, penetration of the plasma inside the anode cavity and the shape of magnetic force lines. Simulated steady-state results show good agreement with experimental measurements. In the full CAMILA case we demonstrate that the ionization region is found in the anode cavity. The electric field inside the anode cavity is substantial and it is directed towards the anode cavity centreline. Electrons are heated sufficiently to reach a high degree of ionization inside the anode cavity while ion currents to the anode surfaces are reduced significantly.
Experimental Investigations of Component Determining CAMILA Hall Thruster Performance
  • Behar
Behar. "Experimental Investigations of Component Determining CAMILA Hall Thruster Performance". Proceedings of the 33 nd International Electric Propulsion Conference (IEPC), October 6-10, 2013, Washington DC, USA, IEPC-2013-235.
MEPS Programme -New Horizons for Low Power Electric Propulsion Systems
  • Tommaso Misuri
  • Mariano Andrenucci
  • Jacob Herscovitz
  • Barak Waldvogel
  • Kathe Dannenmayer
Tommaso Misuri, Mariano Andrenucci, Jacob Herscovitz, Barak Waldvogel and Kathe Dannenmayer. "MEPS Programme -New Horizons for Low Power Electric Propulsion Systems". Proceedings of the 34 th International Electric Propulsion Conference (IEPC), July 4-10, 2015, Hyogo-Kobe DC, USA, IEPC-2015-491.
Scaling Down Hall Thrusetrs
  • E Ahedo
  • J M Gallardo
E. Ahedo and J. M. Gallardo. Scaling Down Hall Thrusetrs. In The 28th International Electric Propulsion Conference (IEPC), 17-21 March, 2003, Toulouse, France, IEPC-03-104.
Theoretical Modeling of Ionization Processes in Anode Cavity of CAMILA Hall Thruster
  • A Kapulkin
  • M Guelman
A. Kapulkin and M. Guelman. "Theoretical Modeling of Ionization Processes in Anode Cavity of CAMILA Hall Thruster". Proceedings of the 31st International Electric Propulsion Conference (IEPC), 20-24 September, 2009, Ann Arbor, Michigan, USA, IEPC-2009-068.
Experimental and Numerical Investigations of the Physical Processes in a Co-Axial Magneto-Isolated Longitudinal Anode Hall Thruster
  • I Kronhaus
Kronhaus, I., "Experimental and Numerical Investigations of the Physical Processes in a Co-Axial Magneto-Isolated Longitudinal Anode Hall Thruster". Ph.D. Dissertation, Aerospace Dept., Technion -Israel Institute of Technology, Haifa, Israel, 2012.