Internal plasma potential measurements of a Hall thruster using xenon and krypton propellant

Linnell, Jesse A.; Gallimore, Alec D.

doi:10.1063/1.2335820

Cited by 49 publications

(44 citation statements)

References 26 publications

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“…For the P5, the ionization region length is approximated as x 12 mm [7]. This value represents a nominal operating condition, and in the context of the performance estimate it is assumed, for simplicity, to be constant.…”

Section: Performance Estimatesmentioning

confidence: 99%

Effect of Anode Temperature on Hall Thruster Performance

Book

Walker

2010

Journal of Propulsion and Power

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The effects of anode temperature on the performance of a 5-kW Hall-effect thruster are investigated. The performance characteristics of the P5 Hall-effect thruster are measured with and without active cooling of the anode. Thrust, ion current density, anode temperature, and cooling power are measured for discharge voltages between 100 and 500 V at xenon propellant flow rates of 4.97 and 10:0 mg=s. All experiments are performed in a 4 by 7 m stainless-steel vacuum chamber at pressures below 2:4 10 5 Torr corrected for xenon. At 100 V, 4:97 mg=s, cooling affects a 6.3% increase in anode efficiency and a 56% increase in thrust-to-power (T=P). At 100 V, 10:0 mg=s, cooling affects a 2.0% increase in anode efficiency and a 7.5% increase in T=P. For both propellant flow rates, the cooled anode efficiency unexpectedly decreases as the discharge voltage increases, which leads to a maximum anode efficiency loss of 5.0 and 9.1% at 4.97 and 10:0 mg=s, respectively. Nomenclature A w = surface area of coolant tube inner wall, m 2 c p = coolant specific heat capacity, J kg 1 K 1 D = inner diameter of coolant tubing, m e = elementary charge, C h = coolant heat transfer coefficient, W m 2 K 1 IF c = ionization fraction with cooling IF uc = ionization fraction without cooling k = Boltzmann's constant, J K 1 k w = coolant thermal conductivity, W m 1 K 1 L=D = coolant tube length-to-diameter ratio m e = electron mass, kg m 0 = neutral atom mass, kg Nu = Nusselt number n e = electron number density, m 3 n 0 = neutral number density, m 3 Pr = Prandtl number q = power extracted by coolant, W Q 0 = electron-neutral collision cross section, m 2 Re = Reynolds number T eV = electron energy, eV T 0 = neutral propellant temperature, K Z c = electron-neutral collision frequency, s 1 = axial flux of neutrals, m 2 s 1 T w = wall to bulk fluid temperature difference, K a = anode efficiency b = current utilization efficiency m = mass utilization efficiency o = utilization efficiency for discharge power T = thruster efficiency v = voltage utilization efficiency = axial penetration distance, m = coolant dynamic viscosity, Pa s h i v e i = ionization reaction rate, m 3 s 1 v = average neutral speed, m s 1 v e0= average electron speed relative to neutrals, m s 1

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Section: Performance Estimatesmentioning

confidence: 99%

Effect of Anode Temperature on Hall Thruster Performance

Book

Walker

2010

Journal of Propulsion and Power

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“…In a typical Hall thruster the impeded electron motion creates the electrostatic field necessary to accelerate propellant ions. Electric equipotential lines and magnetic field lines have been found to correspond in the quasi-neutral plasma 15 because electrons are mobile along field lines. The magnetic field and electric field are essentially orthogonal, giving rise to the dominant azimuthal electron motion and radial thermal motion.…”

Section: Mobility Conceptsmentioning

confidence: 99%

Mobility Studies of a Pure Electron Plasma in Hall Thruster Fields

Fossum

King

Makela

2006

42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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An electron trapping apparatus was constructed in order to study electron dynamics in the defining electric and magnetic fields of a Hall-effect thruster. The approach presented here decouples the cross-field mobility from plasma effects by conducting measurements on a pure electron plasma in a highly controlled environment. Dielectric walls are removed completely eliminating all wall effects; thus, electrons are confined solely by a radial magnetic field and a crossed, independently-controlled, axial electric field that induces the closed-drift azimuthal Hall current. Electron trajectories and cross-field mobility were examined in response to electric and magnetic field strength and background neutral density. Without wall effects or neutral plasma effects mobility is presumed to follow the classical mobility model. In the present research, measurement techniques are investigated, and results are verified against the classical model. Preliminary findings suggest that that the apparatus and techniques used will be valid for mobility studies in more complex field environments. Nomenclature

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“…With the larger zone, the krypton neutrals would have a longer residence time before they were ionized, consequently decreasing the frequency. Additionally, the ionization zone was found to be outside the discharge channel, which decreased the thruster efficiency due to a larger beam divergence [9].…”

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confidence: 98%

Ultrahigh-Speed Imaging of Hall-Thruster Discharge Oscillations With Krypton Propellant

Liu

Huffman

Branam

et al. 2011

IEEE Trans. Plasma Sci.

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The discharge oscillations of a 200-W Hall thruster, with krypton propellant, was captured optically with an ultrahighspeed camera providing information up to 500 kHz. The sequential images provide a temporal 2-D description of the plasma field, which illustrate the direct emission (i.e., visible light emitted by the plasma discharge) of the plasma increasing and decreasing within the thruster channel. These periodic fluctuations of intensity have a frequency of 31 kHz, which is 10% less than the measured breathing-mode frequency utilizing xenon propellant under the same conditions. Index Terms-Breathing modes, Hall thrusters, optical emission, plasma instability. W HILE there are a variety of electric-propulsion devices ranging from the electrodynamic pulsed plasma thrusters to the more electrostatic ion thrusters, the Hall thruster has steadily emerged as a popular solution for the ever increasing assortment of space missions. Although first developed in the U.S., the Russian space program was the first to exploit this advanced thruster in the 1960s for their station-keeping maneuvers. However, in recent years, the Hall thruster reemerged in the West due to its versatility. From station keeping to deepspace missions, the capabilities and performance of the Hall thruster have caught the attention of many institutions such as the National Aeronautic and Space Administration and the United State Air Force.The basic physics of the Hall thruster include an electric field produced by an externally mounted hollow cathode located at the open end of an annular channel and an anode located at the opposite end, which is closed off. Propellant is fed through the anode, which also acts as a gas distributor, and migrates toward the open end of the annular channel or the exit plane. Electrons from the cathode travel toward the anode; however, before they can reach the anode, they are trapped by a magnetic field close to the exit plane, which is perpendicular to the electric field. The trapped electrons begin to collide with the propellant, thus forming plasma. The charged particles (krypton ions in this case) are then accelerated in the electric field providing the exchange in momentum required to generate thrust. As the ions Manuscript Fig. 1. Discharge current (circle) compared with the average visible emission intensity (triangle). The thruster was operating at nominal conditions. V d = 250 V, I d = 0.8 A, andṁ = 0.5 mg/s. leave the thruster, they are neutralized by electrons generated via the hollow cathode [1], [2].A BHT-200 thruster (with a nominal operating power of 200 W) was used in this paper and was operated at nominal conditions. Although the thruster was designed for xenon, krypton was employed in this paper to determine the effects of the alternative propellant.Visible light emitted by the plasma discharge or direct emission was collected with a Shimadzu HyperVision HPV-2 ultrahigh-speed camera capable of recording at one million frames per second (Mfps). The camera has a maximum resolution of 312 by 260 pixels ...

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Internal plasma potential measurements of a Hall thruster using xenon and krypton propellant

Cited by 49 publications

References 26 publications

Effect of Anode Temperature on Hall Thruster Performance

Effect of Anode Temperature on Hall Thruster Performance

Mobility Studies of a Pure Electron Plasma in Hall Thruster Fields

Ultrahigh-Speed Imaging of Hall-Thruster Discharge Oscillations With Krypton Propellant

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