Then present invention relates to Hall thrusters. More particularly, the present invention relates to low power Hall thruster effective for micro-spacecrafts and nano-spacecrafts.
Hall thrusters were developed and studied in the past 40-45 years, till 1992—mainly in the former Soviet Union and after 1992—in the west as well. Over 200 Hall thrusters have been flown on Soviet or Russian satellites in the last thirty years. This technology was used on the European Lunar mission SMART-1 and is used on a number of commercial geostationary satellites.
A worldwide effort is presently being invested in the developments of micro- and nano-spacecraft propelled using advanced electric propulsion engines. The evaluations and experiments carried out up to now show that attempts to solve this problem face considerable difficulties, which had not yet been overcome (reviews are attached herein as references: “Micropropulsion for Small Spacecraft”/Edited by M. M. Micci and A. D. Ketsdever, Progress in Astronautics and Aeronautics, vol. 187, 477 p., 2000.
Among the electric rocket engines that are considered as the candidates for application on micro- and nano-spacecraft, Hall thrusters occupy a prominent place. This is due to the following factors:
It is an object of the present invention to provide a novel low power Hall thruster capable of increasing the efficiency and specific impulse of small power Hall thrusters.
It is yet another object of the present invention to provide a novel low power Hall thruster capable of relatively high lifetime without reducing the efficiency.
Furthermore and in accordance with another preferred embodiment for the present invention, said magnetic system comprises magnetic circuit, magnetic poles, and magnetic coils.
Furthermore and in accordance with another preferred embodiment for the present invention, said magnetic system comprises having magnetic circuit, magnetic poles, and permanent magnets.
Furthermore and in accordance with yet another preferred embodiment fog the present invention, said magnetic system comprises magnetic circuit, magnetic poles and combined magnetic coils and permanent magnets.
Furthermore and in accordance with another preferred embodiment for the present invention, surfaces of said co-axial anode are substantially parallel to the longitudinal axis of the Hall thruster with possible deviation within 20°.
Furthermore and in accordance with another preferred embodiment for the present invention, the magnetic field in the cavity of the anode is parallel to an adjacent surface of the anode.
Furthermore and in accordance with another preferred embodiment for the present invention, said longitudinal magnetic field in the anode cavity is created by special magnetic coils with mutually opposite electric currents and magnetic screens, and wherein the magnetic field is regulated independently of said radial magnetic field in said acceleration channel.
Furthermore and in accordance with another preferred embodiment for the present invention, said longitudinal magnetic field within the anode cavity is created with permanent magnets.
Furthermore and in accordance with another preferred embodiment for the present invention, the length of said co-axial anode is predetermined in accordance with the mass flow rate density in the anode cavity.
Furthermore and in accordance with another preferred embodiment for the present invention, the length of said co-axial anode is regulated by placing said gas distributor in a needed point at the anode cavity.
In order to better understand the present invention and appreciate its practical applications, the following Figures are attached and referenced herein. Like components are denoted by like reference numerals.
It should be noted that the figures are given as examples and preferred embodiments only and in no way limit the scope of the present invention as defined in the appending Description and claims.
The present invention provides a novel low power thruster that is provided with a co-axial magneto-isolated longitudinal anode configured to overcome the limitations in such low power Hall thrusters involved in steady state operation. The co-axial magneto-isolated longitudinal anode concept of the present invention intends to solve the problem of propellant ionization in the low-power Hall thruster by means of aa ionization area extension along with the prevention of ion losses on its walls.
Reference is now made to
One of the primary features of the CAMILA Hall thruster magnetic system is the mostly longitudinal magnetic field in the ionization zone that is located in an anode cavity 120, and mostly radial magnetic field in the acceleration zone 124 near the thruster exit plane. The minimal required value of the longitudinal component of the magnetic field induction in the ionization region is about 0.002 T and depends on the width of the anode cavity. The effectiveness of the propellant ionization in the anode cavity should increase at increasing the induction of the longitudinal magnetic field, according to evaluation that was done by the inventors of the present invention. The magnetic field topography in the anode cavity 120 should be substantially close to symmetric relative to the central surface of the cavity. In the acceleration region, the requirements to the magnetic field configuration and the value of the magnetic induction are the same, to a first approximation, as in common Hall thrusters: symmetry relative to the channel central surface and, which is essential, high positive axial gradient. At large values of the induction of the longitudinal magnetic field in the anode cavity the magnitude of the radial component of the magnetic field induction in the acceleration region can be reduced compared to the conventional Hall thruster. The reduced values of the radial component of the magnetic field can be used as a consequence of the specific feature of the CAMILA Hall thruster. As distinguished from the conventional Hall thruster, in the CAMILA Hall thruster there is more than one “barrier” for the electrons on their way towards the anode. The first barrier is the radial magnetic field in the acceleration region, and the second barrier is the longitudinal magnetic field in the anode cavity.
Reference is now made to
Optionally and in addition to the basic magnetic system, the possibility of using strong permanent magnets instead of anode coils to create the magnetic field in the anode cavity was checked. The permanent magnets are capable of creating high field values and do not require power supply. The results of the calculations show that it is possible to create the required magnetic field configuration in the CAMILA thruster using a combination of the magnetic coils and permanent magnets.
Reference is now made to
Reference is now made to
Optionally and in accordance with yet another preferred embodiment of the present invention, all magnetic coils in the Hall thruster can be replaced by permanent magnets. The anode coils, as in the previous case were replaced by the permanent magnets. In addition, the part of the inner magnetic pole piece was also replaced by a permanent magnet. The analysis demonstrated that it is possible to create appropriate magnetic field configuration using only permanent magnets.
Reference is now made to
Reference is now made to
It should be noted that CAMILA differs from the conventional Hall thruster in two main aspects:
In order to understand the operation of the CAMILA Hall thruster, reference is made again to
It should be clear that the description of the embodiments and attached Figures set forth in this specification serves only for a better understanding of the invention, without limiting its scope as covered by the following claims.
It should also be clear that a person skilled in the art, after reading the present specification can make adjustments or amendments to the attached Figures and above described embodiments that would still be covered by the following claims.
This patent application is based upon and claims the benefit of the filing date of co-pending U.S. Provisional Patent Application Serial No. 60/865,033, filed Nov. 9, 2006, entitled LOW POWER HALL THRUSTER, by the inventors of the present application, which application is incorporated herein in its entirety.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IL2007/001384 | 11/11/2007 | WO | 00 | 1/11/2010 |
Publishing Document | Publishing Date | Country | Kind |
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WO2008/056369 | 5/15/2008 | WO | A |
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International Preliminary Report on Patentability Dated May 12, 2009 From the International Bureau of WIPO Re. Application No. PCT/IL2007/001384. |
International Search Report and the Written Opinion Dated Mar. 11, 2008 From the International Searching Authority Re. Application No. PCT/IL2007/001384. |
Communication Pursuant to Article 94(3) EPC Dated Feb. 3, 2016 From the European Patent Office Re. Application No. 07827357.0. |
Number | Date | Country | |
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20100107596 A1 | May 2010 | US |
Number | Date | Country | |
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60865033 | Nov 2006 | US |