|
Descripción
|
|
|---|---|
| The next generation of satellites will make use of the recent developments in space propulsion by accelerated plasma streams. The advantages of electric propulsion (EP) for longterm missions rely in combined reasons of economy and practical interest. These systems produce ion streams up to exhaust velocities of tens of kilometers per second, higher than those of conventional chemical or bipropellant systems. This fact provides higher values of the specific impulse and brings relevant weight savings over traditional propulsion systems. In addition, the EP engines are powered by electric the solar panels and make use of chemically inert gases as propellant (usually xenon) of easy stowage. Therefore, EP offers considerable advantages for in orbit station keeping of geostationary satellites, deep space missions or planetary probes. This field has received a special attention (topic C) within the Horizon 2020 CEE research program for space and will face a strong competition n the following years. In this communication the characterization of the exhaust plasma streams from the prototype ALPHIE (Adaptable Low Power Hybrid Ion Engine) designed for small and medium satellites is discussed. The classical collecting and emissive Langmuir plasma probes provide local measurements allowing the mapping of the outgoing plasma flow. In particular, the spatial profile of the plasma potential is of paramount relevance to determine the local electric fields governing the dispersion of the plasma stream. The diagnostic using emissive Langmuir probes is reviewed with emphasis in low density plasmas. Relevant details of this technique, such as the strong or weak emission modes, probe length, etc. that are frequently overlooked and might potentially mislead the experimental results are discussed. The measurements could also be dramatically affected by careless signal conditioning and/or defective circuit grounding. As we shall see, our results support the conclusion that potential structures around the probe, as the virtual cathodes, would be responsible for the operation of emissive probes in low density plasmas. The determination of the energy spectrum of outgoing low energy ions is also discussed. This parameter modulates the effective thrust imparted by the ion engine and is critical because unwanted ion flows might affect the operation of nearby payloads by ion bombardment. | |
|
Internacional
|
Si |
|
ISSN o ISBN
|
|
|
Entidad relacionada
|
|
|
Nacionalidad Entidad
|
BULGARIA |
|
Lugar del congreso
|
Kiten, Bulgaria |