| タイトル | Barium Depletion in the NSTAR Discharge Cathode After 30,000 Hours of Operation |
| 著者（英） | Capece, Angela M.; Katz, Ira; Polk, James E.; Mikellides, Ioannis G. |
| 著者所属（英） | Jet Propulsion Lab., California Inst. of Tech. |
| 発行日 | 2010-07-25 |
| 言語 | eng |
| 内容記述 | Dispenser hollow cathodes rely on a consumable supply of barium released by impregnant materials in the pores of a tungsten matrix to maintain a low work function surface. Examinations of cathode inserts from long duration ion engine tests show deposits of tungsten at the downstream end that appear to block the flow of barium from the interior. In addition, a numerical model of barium transport in the insert plasma indicates that the barium partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant barium-producing reaction, and it was postulated previously that this would suppress barium loss in the upstream part of the insert. New measurements of the depth of barium depletion from a cathode insert operated for 30,352 hours reveal that barium loss is confined to a narrow region near the downstream end, confirming this hypothesis. |
| NASA分類 | Spacecraft Propulsion and Power |
| 権利 | Copyright |
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