An Overview of the Nuclear Electric Xenon Ion System (NEXIS) Program

Polk, Jay; Goebel, Don; Brophy, John R.; Beatty, John; Monheiser, Jeff; Giles, D.; Hobson, David; Wilson, Fred; Christensen, J.A.; Pano, M. De; Hart, Stephen L.; Ohlinger, Wayne L.; Hill, D. N.; Williams, John D.; Wilbur, P. J.; Laufer, D.; Farnell, Casey C.

doi:10.2514/6.2003-4713

Cited by 23 publications

(8 citation statements)

References 8 publications

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“…For this case, the model agrees with experimental data that show that the peak on the axis of the beam profile is largely due to double ion current. The "Data" profile is extrapolated from the NSTAR TH15 data found in Reference [7]. The jB[++] profile shows generally good agreement with the Data profile, though some discrepancy is found near r ~ 3cm and r ~ 13cm.…”

Section: Comparison With Experimental Resultsmentioning

confidence: 99%

“…The jB[++] profile shows generally good agreement with the Data profile, though some discrepancy is found near r ~ 3cm and r ~ 13cm. [7] also included a performance sensitivity analysis that was conducted after the thruster had operated for several thousand hours. During this analysis, the main flow rate was changed over a range of ± 9%, while the beam current was kept constant, resulting in the discharge performance trend shown in Figure 5.2-4.…”

Section: Comparison With Experimental Resultsmentioning

confidence: 99%

“…These parameters are important to understanding the fundamental behavior of the discharge, as described in Reference [32]. Where possible, these values are compared with the NSTAR data from Reference [7]. The values for η ud [*] and ε B are very similar since they are determined by the conditions that define the throttle points from Table 5.1-1.…”

Section: Comparison With Experimental Resultsmentioning

confidence: 99%

“…The validation of high-power, long-life ion thrusters for the missions in Section 1.2 requires a better understanding of ion thruster performance, life, and scaling. Experimental life tests, such as the 8,200-hour and 30,000-hour NSTAR life test, are impractical and prohibitively expensive for validating ion thruster life and performance for future long-duration, high-power missions [7,5]. Thruster component wear changes the performance of the thruster over the life of the mission.…”

Section: A Background and Motivationmentioning

confidence: 99%

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Plasma Processes of DC Ion Thruster Discharge Chambers

Wirz¹,

Katz²

2005

41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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This study has advanced state-of-the-art discharge modeling and revealed important aspects of discharge plasma processes. These extensions of existing ion thruster technology and understanding are necessary to fulfill the needs of future space missions. A multi-component hybrid 2-D computational Discharge Chamber Model (DCM) was developed to help identify important ion thruster discharge processes and investigate miniaturization issues. The model is designed to integrate thruster component (cathode and grid) wear models to allow the determination of thruster life and long-term performance. The model accounts for the five major chamber design parameters (chamber geometry, magnetic field, discharge cathode, propellant feed, ion extraction grid characteristics) and self-consistently tracks the effects of the four plasma species (neutral propellant atoms, secondary electrons, primary electrons, and ions). Results from the model show good agreement with experimental data at two operating points for the 30cm NSTAR ion thruster. A thruster design sensitivity performed with DCM suggests that NSTAR thruster performance is greatly enhanced by increasing the strength of the middle magnet ring. The model analyses show that the peak observed in the NSTAR beam profile is due to double ions that are created by overconfinement of primary electrons on the thruster axis. Design sensitivity results show that, at the NSTAR thruster scale, efficient confinement of primary electrons is relatively easy to achieve; therefore, efforts to improve thruster performance should focus on effectively utilizing the primary electrons to minimize double ion production and maximize the number of single ions extracted to the beam. DCM results also show that non-classical effects are important for predicting the perpendicular mobility of secondary electrons in ion thruster discharges. Good agreement with experimental data was found by weighting the influence of Bohm-type diffusion by considering the non-uniform levels of ionization in the discharge. It was found that ion thrusters operate in an intermediately ionized plasma regime that is between fully and weakly ionized approximations. The observations from this study have furthered the understanding of discharge processes and should improve future ion thruster design and modeling efforts. DCM advances state-of-the-art ion thruster modeling and provides a framework for a complete thruster model that can be used for long-life performance assessment and life validation.

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Section: Comparison With Experimental Resultsmentioning

confidence: 99%

Section: Comparison With Experimental Resultsmentioning

confidence: 99%

Section: Comparison With Experimental Resultsmentioning

confidence: 99%

Section: A Background and Motivationmentioning

confidence: 99%

See 2 more Smart Citations

Plasma Processes of DC Ion Thruster Discharge Chambers

Wirz¹,

Katz²

2005

41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

View full text Add to dashboard Cite

show abstract

“…I. Introduction M ANY long-duration space missions (up to 50 kh) have been proposed over the past two decades that would use electric propulsion in the form of ion [1] and Hall thrusters [2]. Hollow cathodes, which both ionize the propellant and neutralize the exhaust in most forms of electric propulsion, must also be able to meet these increasingly demanding requirements on lifetime and current.…”

Section: Doi: 102514/1b36788mentioning

confidence: 99%