High Current Cathode Development for 50 kW Class Hall Thrusters

John, Judy St.; Sarver-Verhey, Timothy R.; Jacobson, David T.; Kamhawi, Hani

doi:10.2514/6.2005-4244

Cited by 3 publications

(7 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…14,15,16,23 Cathode-to-ground voltage results in Figure 8 indicate that, in general, the cathode-toground voltage became more negative as the flow rate was increased. At a flow rate of 19 sccm, configuration 1 operated in plume mode for all discharge currents.…”

Section: Resultsmentioning

confidence: 90%

“…This trend has been reported by others and was expected. 14,15,16,25,26 Increasing the cathode flow rate results in increased plasma density inside the emitter; this results in increased plasma fluxes to the emitter surface which slightly increases the emitter temperature. 26 Although there exists no direct emitter surface temperature measurements for high current cathodes (> 50 A), previous studies have used the cathode orifice plate tip temperature as a measure and indicator of the peak emitter temperature.…”

Section: A Emitter Temperaturementioning

confidence: 98%

“…Previous studies have shown that increased cathode orifice diameters will result in reduced cathode orifice plate tip temperatures. 13,15 To determine the cathode orifice plate tip temperature reduction due to the increased cathode orifice size would require testing of a new cathode configuration that utilizes configuration 2 novel emitter and configuration 1 cathode orifice diameter. Manufacturing, assembly, and testing of a new cathode configuration is not feasible, so numerical simulations with JPL's OrCa2D code will be used to help understand and elucidate configuration 1 and 2 test results at the different operating conditions.…”

Section: A Emitter Temperaturementioning

confidence: 99%

“…14 The results indicated that at an emission current of 100 A, the cathode orifice plate tip temperature was between 1360 C and 1400 C. In 2005, another effort was undertaken to demonstrate a 100 A HCA that can have a long life capability and that can operate at temperatures lower than the temperatures demonstrated by the 2001 HCA. 15 Several configurations were assembled and tested. The best performing configuration demonstrated an orifice plate tip temperature between 1300 C and 1320 C at 100 A.…”

Section: Past High Current Hollow Cathode Development At Nasa Grcmentioning

confidence: 99%

“…26 Although there exists no direct emitter surface temperature measurements for high current cathodes (> 50 A), previous studies have used the cathode orifice plate tip temperature as a measure and indicator of the peak emitter temperature. 13,14,15,16 Direct emitter surface temperature measurements were performed by Polk et al on a NEXT NCA type cathode. 23 The measurements indicated that indeed the cathode orifice plate tip temperature is an indicator of the peak emitter temperature in most cases.…”

Section: A Emitter Temperaturementioning

confidence: 99%

See 4 more Smart Citations

Development and Testing of High Current Hollow Cathodes for High Power Hall Thrusters

Kamhawi

Noord²

2012

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

Self Cite

View full text Add to dashboard Cite

NASA's Office of the Chief Technologist In-Space Propulsion project is sponsoring the testing and development of high power Hall thrusters for implementation in NASA missions. As part of the project, NASA Glenn Research Center is developing and testing new high current hollow cathode assemblies that can meet and exceed the required discharge current and life-time requirements of high power Hall thrusters. This paper presents test results of three high current hollow cathode configurations. Test results indicated that two novel emitter configurations were able to attain lower peak emitter temperatures compared to state-of-the-art emitter configurations. One hollow cathode configuration attained a cathode orifice plate tip temperature of 1132 °C at a discharge current of 100 A. More specifically, test and analysis results indicated that a novel emitter configuration had minimal temperature gradient along its length. Future work will include cathode wear tests, and internal emitter temperature and plasma properties measurements along with detailed physics based modeling. NomenclatureA = Ampere A o = Universal constant, 120 A/cm 2 C = fit coefficient J d = discharge current density, A/cm 2 J e = return electron current density, A/cm 2 J em = emission cathode current density, A/cm 2 J ion = return ion current density, A/cm 2 J orif = orifice current density, A/cm 2 k = Boltzmann constant, 1.38×10 -23 Joules/K m e = electron mass, 9.1x10 -31 kg n e = electron number density, m -3 q e = electron charge, 1.609×10 -19 Coulomb sccm = standard cubic centimeter per minute T e = electron temperature, eV T emit = emitter temperature, K t = lifetime, hours t depth = time to barium depletion depth, hours V a = energy of activation x = axial position y depth = depth into emitter α = emitter constant, eV/K φ w = emitter work function, eV φ o = temperature independent work function, eV sheath = sheath potential, V * Aerospace Engineer, Propulsion and Propellants Branch, hani.kamhawi-1@nasa.gov, Associate AIAA Fellow. † Aerospace Engineer, Propulsion and Propellants Branch, jonathan.l.vannoord@nasa.gov, Senior AIAA Member.

show abstract

Section: Resultsmentioning

confidence: 90%