VX-200 Magnetoplasma Thruster Performance Results Exceeding Fifty-Percent Thruster Efficiency

Longmier, Benjamin W.; Cassady, Leonard D.; Ballenger, Maxwell G.; Carter, Mark D.; Chang‐Diaz, Franklin; Glover, T. W.; Ilin, Andrew V.; McCaskill, Greg; Olsen, C.; Squire, Jared P.; Bering, Edgar A.

doi:10.2514/1.b34085

Cited by 43 publications

(24 citation statements)

References 31 publications

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“…As the force exerted on the thruster structure is equal in magnitude and opposite in direction to the thrust, the thrust is accurately estimated from a spatial displacement occurring with the thruster operation. When the devices have heavy structures as being a variable specific impulse magnetoplasma rocket (VASIMR), 5 it would be difficult to mount the thruster head on the thrust balance and the displacement arising from the thrust force would be very small even if it can be mounted. Furthermore, the spatial displacement is often caused by the magnetic force arising from the applied magnetic field and/or discharge current, as investigated by Haag.…”

Section: Introductionmentioning

confidence: 99%

Measurement of plasma momentum exerted on target by a small helicon plasma thruster and comparison with direct thrust measurement

Takahashi

Komuro

Andõ

2015

Review of Scientific Instruments

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Momentum, i.e., force, exerted from a small helicon plasma thruster to a target plate is measured simultaneously with a direct thrust measurement using a thrust balance. The calibration coefficient relating a target displacement to a steady-state force is obtained by supplying a dc to a calibration coil mounted on the target, where a force acting to a small permanent magnet located near the coil is directly measured by using a load cell. As the force exerted by the plasma flow to the target plate is in good agreement with the directly measured thrust, the validity of the target technique is demonstrated under the present operating conditions, where the thruster is operated in steady-state. Furthermore, a calibration coefficient relating a swing amplitude of the target to an impulse bit is also obtained by pulsing the calibration coil current. The force exerted by the pulsed plasma, which is estimated from the measured impulse bit and the pulse width, is also in good agreement with that obtained for the steady-state operation; hence, the thrust assessment of the helicon plasma thruster by the target is validated for both the steady-state and pulsed operations.

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Section: Introductionmentioning

confidence: 99%

Measurement of plasma momentum exerted on target by a small helicon plasma thruster and comparison with direct thrust measurement

Takahashi

Komuro

Andõ

2015

Review of Scientific Instruments

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“…In recent years there has been significant interest in helicon discharges in expanding magnetic fields for applications such as spacecraft propulsion [1] and plasma processing [2] as well as for studies in basic plasma science [3][4][5][6]. Helicon discharges are used to efficiently produce plasma [7] while the diverging magnetic field produces an ion beam which has the potential for producing thrust for space applications or etching in processing applications [2,8].…”

Section: Introductionmentioning

confidence: 99%

Temperature gradients due to adiabatic plasma expansion in a magnetic nozzle

Sheehan¹,

Longmier²,

Bering³

et al. 2014

Plasma Sources Sci. Technol.

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A mechanism for ambipolar ion acceleration in a magnetic nozzle is proposed. The plasma is adiabatic (i.e., does not exchange energy with its surroundings) in the diverging section of a magnetic nozzle so any energy lost by the electrons must be transferred to the ions via the electric field. Fluid theory indicates that the change in plasma potential is proportional to the change in average electron energy. These predictions were compared to measurements in the VX-200 experiment which has conditions conducive to ambipolar ion acceleration. A planar Langmuir probe was used to measure the plasma potential, electron density, and electron temperature for a range of mass flow rates and power levels. Axial profiles of those parameters were also measured, showing consistency with the adiabatic ambipolar fluid theory.

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“…This conclusion again agrees with the results seen by Linell, who states that "the beam divergence accounts for a loss equally important as propellant utilization" when referring to operation with krypton versus xenon propellant. 27 An interesting observation is that diatomic nitrogen and argon have nearly the same first ionization energy, 15.58 eV and 15.76 eV, respectively, compared to 12.13 eV for xenon. 28 Despite the fact that rotational and vibrational energy modes can sink energy away from a nitrogen discharge and not an argon one, no significant difference in voltage utilization or propellant utilization is seen.…”

Section: A Single-stage Operationmentioning

confidence: 94%

“…Some of this work involves the use of a helicon source alone as a thruster, [11][12][13][14] while other propulsion systems attempt to use the helicon source as an ionization stage, with a separate acceleration stage. [15][16][17] Previous work has also demonstrated the operation of an annular helicon source, which may be applied as an ionization stage for a two-stage Hall thruster. 18 The Helicon Hall thruster (HHT) is a two-stage thruster designed to utilize the efficient ionization of a helicon plasma source with the acceleration mechanism of a Hall thruster.…”

Section: Introductionmentioning

confidence: 99%

Performance of a Helicon Hall Thruster Operating with Xenon, Argon, and Nitrogen

Shabshelowitz

Gallimore²,

Peterson

2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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The Helicon Hall Thruster (HHT) is a two-stage thruster that was developed to investigate whether a radiofrequency ionization stage can improve the overall efficiency of a Hall thruster operating at high thrust and low specific impulse. This experiment measured the single-stage and two-stage performance of the HHT for 10-25 mg/s anode mass flow rates of xenon at 100-200 V discharge voltages, and also for 6 mg/s of argon at 300 V, and 2.6 mg/s of nitrogen at 200 V. Argon and nitrogen performance are characterized by low beam divergence efficiency and low propellant utilization efficiency. During two-stage operation, the thrust of the HHT increased slightly with rf power, but the propulsive efficiency and thrust-to-power both decreased with increasing rf power. Probe diagnostics suggest that gains were realized by a slight increase in propellant efficiency, but that the rate of increase was not sufficient to overcome the increase in power. NomenclatureA c,eff = Faraday probe effective collection area [m 2 ] e = elementary charge [C] E 1 = voltage exchange parameter [-] E 2 = mass exchange parameter [-] = Faraday constant [C/mol] I axial = axial component of ion beam current [A] I beam = ion beam current [A] I c = current collected by probe [A] I d = discharge current [A] I sp,a = anode specific impulse [s] I sp,a + = theoretical anode specific impulse of a singly-charged plasma [s] = molar mass [kg/mol] m i = ion mass [kg] = total thruster mass flow rate [kg/s] = anode mass flow rate [kg/s] = cathode mass flow rate [kg/s] P d = discharge power [W] P elec = total electrical power [W] P dc = dc discharge power [W] P mag = magnet power [W] P rf = rf power [W] P thrust = jet power of thruster exhaust [W] 2 r = Faraday probe distance from thruster [m] T = measured thrust [N] T + = theoretical thrust of a thruster with singly-charged plasma [N] = average axial velocity of exhaust particle [m/s] V d = discharge voltage [V] V mp = most probable energy of exhaust ions [V] V p = plasma potential [V] = anode efficiency [-] = anode efficiency of a thruster with singly-charged plasma [-] = cathode efficiency [-] = discharge efficiency [-] = magnet power efficiency [-] = current utilization efficiency [-] = rf power efficiency [-] = total efficiency [-] = voltage utilization efficiency [-] θ = angular position of Faraday probe [radians] λ = effective exhaust divergence angle [degrees] = propellant utilization efficiency [-] = beam divergence efficiency [-]

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VX-200 Magnetoplasma Thruster Performance Results Exceeding Fifty-Percent Thruster Efficiency

Cited by 43 publications

References 31 publications

Measurement of plasma momentum exerted on target by a small helicon plasma thruster and comparison with direct thrust measurement

Measurement of plasma momentum exerted on target by a small helicon plasma thruster and comparison with direct thrust measurement

Temperature gradients due to adiabatic plasma expansion in a magnetic nozzle

Performance of a Helicon Hall Thruster Operating with Xenon, Argon, and Nitrogen

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