Since the beginning of FEEP research, it was generally believed that the operational field of this thruster should be limited to high altitude orbits due to possible contamination of the emitter resulting from propellant interaction with the residual atmosphere. In fact, cæsium reacts with water and oxygen forming cæsium hydroxide (CsOH - melting point 272 °C) and cæsium oxide (Cs2O - melting point 400 °C), respectively. These compounds may obstruct the emitter slit, provoking performance degradation, and eventually preventing ion emission. In view of the forthcoming FEEP flight test on the NASA Shuttle, it is mandatory to assess the risk of FEEP failure due to the background environment surrounding the Shuttle. This paper reports the results of a series of high background pressure tests carried out at Centrospazio using an emitter with a 5 mm long, 1.4 micron high slit, and draws general conclusions on the suitability of FEEP emitters to LEO satellite applications. Experiments included tests at a pressure as high as 10-4 mbar, tests with a significant H2O partial pressure (up to 10-7 mbar), and tests carried out to investigate the effect of prolonged switch off periods (up to 15 hours). As a result of this work, enhanced confidence in the use of FEEP at high pressure was gained. While additional, systematic tests are obviously necessary and are highly recommended, it can be affirmed that the thruster behaviour is not as influenced by the background atmospheric environment as previously believed, even with a relative

FEEP Thruster Performance at High Background Pressure

MARCUCCIO, SALVO;ANDRENUCCI, MARIANO
1997-01-01

Abstract

Since the beginning of FEEP research, it was generally believed that the operational field of this thruster should be limited to high altitude orbits due to possible contamination of the emitter resulting from propellant interaction with the residual atmosphere. In fact, cæsium reacts with water and oxygen forming cæsium hydroxide (CsOH - melting point 272 °C) and cæsium oxide (Cs2O - melting point 400 °C), respectively. These compounds may obstruct the emitter slit, provoking performance degradation, and eventually preventing ion emission. In view of the forthcoming FEEP flight test on the NASA Shuttle, it is mandatory to assess the risk of FEEP failure due to the background environment surrounding the Shuttle. This paper reports the results of a series of high background pressure tests carried out at Centrospazio using an emitter with a 5 mm long, 1.4 micron high slit, and draws general conclusions on the suitability of FEEP emitters to LEO satellite applications. Experiments included tests at a pressure as high as 10-4 mbar, tests with a significant H2O partial pressure (up to 10-7 mbar), and tests carried out to investigate the effect of prolonged switch off periods (up to 15 hours). As a result of this work, enhanced confidence in the use of FEEP at high pressure was gained. While additional, systematic tests are obviously necessary and are highly recommended, it can be affirmed that the thruster behaviour is not as influenced by the background atmospheric environment as previously believed, even with a relative
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/50281
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