Efficacy of Electron Mobility Models in Hybrid-PIC Hall Thruster Simulations

Hofer, Richard R.; Katz, Ira; Mikellides, Ioannis G.; Goebel, Dan M.; Jameson, Kristina K.; Sullivan, Regina; Johnson, L. K.

doi:10.2514/6.2008-4924

Cited by 74 publications

(79 citation statements)

References 38 publications

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“…In the post-1990 era, numerous efficiency analysis frameworks and modifications have been proposed [33][34][35][36][37], including notable studies by Komurasaki and Arakawa [38], Ahedo et al [39], and Hofer et al [40,41]. The difference between the proposed architecture with past ion thruster studies, the analytical factorization in Russian literature, and the post-1990 methodologies varies in each case.…”

Section: Historical Perspective and Recent Effortsmentioning

confidence: 96%

Methodology and Historical Perspective of a Hall Thruster Efficiency Analysis

Brown

Larson

Beal

et al. 2009

Journal of Propulsion and Power

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A Hall thruster performance architecture was developed based on separation of the total thrust directed along thruster centerline into mass-weighted and momentum-weighted terms. With this formulation, the total thruster efficiency equation was analytically decomposed to explicitly account for the effects of energy conversion losses, plume divergence, and the velocity distribution function of the propellant jet. Thruster efficiency is defined as the product of 1) energy efficiency, 2) propellant efficiency, and 3) beam efficiency. Energy efficiency comprises losses due to ionization processes and losses that manifest as Joule heating, and contains no information about the vector properties of the jet. Propellant efficiency incorporates losses from dispersion in the jet composition and is unity for 100% ionization to a single ion species. The effect of neutrals on dispersion of the jet velocity distribution function in propellant efficiency is introduced in the neutral-gain utilization. The beam efficiency accounts for divergence of the jet and is ideal when the ion velocity vectors are parallel to the thrust axis. Plume divergence is defined as a momentum-weighted term, and the approximation as a charge-weighted term is characterized. The efficiency architecture is derived from first principles and is applicable to all propulsion employing electrostatic acceleration, including Hall thrusters and ion thrusters. Distinctions and similarities to several past methodologies are discussed, including past ion thruster analyses, early Russian performance studies, and contemporary architectures. To illustrate the potential for enhanced understanding of loss mechanisms and ionization processes with an array of farfield plume diagnostics, a case study is presented of low-discharge voltage operation from a 6 kW laboratory Hall thruster. Nomenclature A = spherical shell surface area element in the plume E 1 = voltage exchange parameter E 2 = mass exchange parameter F = thrust density vector in the plume F = Faraday constant, 96; 485 C=mol of charge f j = normalized ion mass flow fraction of jth ion species fv = velocity distribution function of ions and neutrals g = Earth's gravitational constant at sea level, 9:806 m=s 2 I Axial = axial component of beam current parallel to thruster centerline I Beam = integrated beam current I d = anode discharge current I sp = total specific impulse J = current density in the plume at angular position j = propellant charge state index, 0, 1, 2, 3, etc., for Xe 0 , Xe 1 , Xe 2 , Xe 3 M = molecular weight of propellant, Xe 0:1313 kg=mol _ m i = mass flow rate of ions, where P _ m j _ m i for j 1 to the jth ion species _ m j = mass flow rate of jth species _ m T = total mass flow rate to the anode and cathode, where P _ m j _ m T for j 0 to the jth ion species _ m = mass flux at angular position P d = discharge power to the anode P jet = jet power P loss = power lost to Joule heating processes P min = minimum power required to sustain ionization Q = average charge of propellant ions R = downst...

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Section: Historical Perspective and Recent Effortsmentioning

confidence: 96%

Methodology and Historical Perspective of a Hall Thruster Efficiency Analysis

Brown

Larson

Beal

et al. 2009

Journal of Propulsion and Power

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“…The original version of this thruster was a joint development between AFRL, JPL and the University of Michigan [24], [26]- [29]. The data collected on this thruster at JPL is used to validate plasma simulations [19], [23], [30] intended to evaluate thrusters being considered for NASA science missions. Details on the experimental configuration and thruster performance can be found in [21] and [31].…”

Section: Experimental Apparatusmentioning

confidence: 99%

Conducting Wall Hall Thrusters

Goebel¹,

Hofer

Mikellides³

et al. 2015

IEEE Trans. Plasma Sci.

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A unique configuration of the magnetic field and channel geometry near the wall of Hall thrusters, called magnetic shielding, has recently demonstrated the ability to significantly reduce the erosion of the boron nitride (BN) walls and extend the life of Hall thrusters by orders of magnitude. The ability of magnetic shielding to minimize interactions between the plasma and the discharge chamber walls in regions where erosion typically occurs has for the first time enabled the replacement of insulating walls with conducting materials without loss in Hall thruster performance. It is important to note that this is not a thruster with anode layer (TAL) where the walls are at or near cathode potential, but is a Hall thruster configuration where the walls are near the anode potential. The BN rings in the 6-kW H6 Hall thruster were replaced with graphite that self-biased to near the anode potential during operation. The thruster efficiency remained over 60% (within 2% of the baseline BN configuration) with a small decrease in thrust and increase in Isp typical of magnetically shielded Hall thrusters. The graphite wall temperatures decreased significantly compared with both shielded and unshielded BN configurations, leading to the potential for higher power operation. Eliminating ceramic walls makes it simpler and less expensive to fabricate a thruster to survive launch loads, and the graphite discharge chamber radiates more efficiently, which increases the power capability of the thruster compared with conventional Hall thruster designs.Index Terms-Hall effect devices, plasma propulsion.

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“…For example, the time dependent neutral gas density computed along the middle of the channel in a 6 kW laboratory Hall thruster [4] using the hybrid-PIC simulation code ''HPHall'' [1,2], is shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%