Simple numerical model describing discharge parameters in orificed hollow cathode devices

Capacci, M.; Minucci, M. A. S.; Severi, Alberto

doi:10.2514/6.1997-2791

Cited by 14 publications

(11 citation statements)

References 3 publications

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“…As shown experimentally in studies [25], [35] and theoretically found in [18], [34] insert wall temperature is an increasing function of discharge current. Furthermore, at a given discharge current, emitter wall temperature shows an increasing trend with propellant flow rate as observed by Goebel [36].…”

Section: Resultssupporting

confidence: 54%

“…However, this variations are negligibly small, as also shown in [34]. The calculated insert region plasma electron temperature is around 1.03 eV.…”

Section: Resultssupporting

confidence: 54%

“…It is also found that the emitter plasma electron temperature is an increasing function of mass flow rate. However, this variations are negligibly small, as also shown in [34].…”

Section: Resultsmentioning

confidence: 56%

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Global Numerical Model for the Assessment of the Effect of Geometry and Operation Conditions on Insert and Orifice Region Plasmas of a Thermionic Hollow Cathode Electron Source

Korkmaz

Çelik

2014

Contrib. Plasma Phys.

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Thermionic hollow cathodes have been widely used in wide variety of areas such as spacecraft electric propulsion systems, material processing and lasers for more than half a century as efficient electron sources. Especially in electric propulsion systems, hollow cathodes are being used as electron sources for propellant ionization and ion beam neutralization. Moreover, it is also a promising candidate for utilization as a stand-alone propulsion system in microsatellites or nanosatellites due to its small physical size, low power consumption and ease of operation. On the other hand, the small geometry of the typical orificed hollow cathodes makes the plasma diagnostics difficult which is why numerical studies become important for understanding the driving physical processes behind their operation, and the effects of the geometry and the operation parameters on cathode performance. In this paper, a global numerical model for the insert and orifice plasma of a hollow cathode is presented where volume averaged plasma parameters are considered for both regions. The results of this study show that the developed model can be used for designing and sizing orificed hollow cathodes as comparisons with the results of experimental and other numerical studies are in good agreement with the ones obtained from the developed model.

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Section: Resultssupporting

confidence: 54%

“…However, this variations are negligibly small, as also shown in [34]. The calculated insert region plasma electron temperature is around 1.03 eV.…”

Section: Resultssupporting

confidence: 54%

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Global Numerical Model for the Assessment of the Effect of Geometry and Operation Conditions on Insert and Orifice Region Plasmas of a Thermionic Hollow Cathode Electron Source

Korkmaz

Çelik

2014

Contrib. Plasma Phys.

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“…This previous work assumed that the cathode temperatures were known by measurements. Several previous researchers have investigated hollow cathode thermal processes both experimentally and analytically [4][5][6][7][8]. The hollow cathode thermal model of Van Noord [9] is very similar in approach to the present work, however, it relies on plasma parameters measured along the centerline as measured by Sahli [7].…”

mentioning

confidence: 98%

Thermal Model of the Hollow Cathode Using Numerically Simulated Plasma Fluxes

Katz

Mikellides

Polk

et al. 2007

Journal of Propulsion and Power

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The first results from a hollow cathode thermal model are presented. The thermal model uses the spatially distributed plasma fluxes, calculated by a two-dimensional axisymmetric model of the plasma inside the emitter region, as the heat source to predict the hollow cathode and insert temperatures. The computed insert temperature profiles are compared with measured values for a cathode similar to the 0.635-cm diameter discharge cathode used in the NASA solar electric propulsion technology applications readiness ion engine. The insert temperatures can be used to predict cathode life from barium depletion. The present results and related experimental studies yield three important conclusions. First, the emitter in the NASA solar electric propulsion technology applications readiness hollow cathode does not operate in the emission-limited regime. The thermionic electron current is about 20 A higher than the discharge current and requires significant reverse electron flux from the plasma to satisfy current continuity. Second, the high-plasma density near the centerline of the cathode results in power deposition on the orifice plate that is more than twice the emitter power deposition. Third, despite a higher heat load to the orifice plate, the operating temperature where it would be measured by a thermocouple is approximately 100 C lower than the emitter. The lower orifice plate temperature is due to poor thermal contact between the emitter and the cathode tube and higher than anticipated radiative losses from the external surface of the heater. Nomenclature F = geometrical configuration factor IP = ionization potential, V j emission = emission current density, A=m 2 j the e = plasma thermal current density, A=m 2 j i = plasma ion current density, A=m 2 _ q rad = heat loss by radiation, W=m 2 _ q emission = heat loss by electron emission, W=m 2 _ q e = heating by plasma electrons, W=m 2 _ q i = heating by plasma ion flux, W=m 2 T = material temperature, K T e = plasma electron temperature, eV WF = emitter work function, eV ij = Kronecker delta " = material emissivity = material thermal conductivity, W=m K = Stephan-Boltzman constant, W=m 2 K 4 sheath = sheath potential, V Introduction H IGH-POWER, long-life electric thrusters were considered necessary as NASA planned many of the challenging missions under the Prometheus program. These missions might have required an increase in both life and emission current compared with hollow cathodes used on NASA's Deep Space 1 spacecraft. Although both the discharge and neutralizer hollow cathodes were operating at the end of the NASA solar electric propulsion technology applications readiness (NSTAR) thruster 30,000-h extended life test [1], the future missions may be even more challenging. A previous life test of the International Space Station plasma contactor hollow cathode [2] ended after 28,000 h, when the cathode would no longer ignite. One scenario for end of life is when the insert can no longer provide free barium to lower the work function and the remaining barium in th...

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“…First the electron temperature is varied to satisfy Equation (1). Next, the number density is determined, satisfying Equation (8).…”

Section: Nasa/t_2002-211916mentioning

confidence: 99%

A Particle and Energy Balance Model of the Orificed Hollow Cathode

Domonkos

2002

38th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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Simple numerical model describing discharge parameters in orificed hollow cathode devices

Cited by 14 publications

References 3 publications

Global Numerical Model for the Assessment of the Effect of Geometry and Operation Conditions on Insert and Orifice Region Plasmas of a Thermionic Hollow Cathode Electron Source

Global Numerical Model for the Assessment of the Effect of Geometry and Operation Conditions on Insert and Orifice Region Plasmas of a Thermionic Hollow Cathode Electron Source

Thermal Model of the Hollow Cathode Using Numerically Simulated Plasma Fluxes

A Particle and Energy Balance Model of the Orificed Hollow Cathode

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