Advanced Space Propulsion CISAS Propulsion Group
Plasma Experiment
The main objective of the experimental campaign is to achieve the best source and magnetic nozzle configuration to maximize the propulsive efficiency. The apparatus is continuously updated to match the requirements of the ongoing activities.
A customized design is fundamental in order to perform a flexible and fast change of the key components involved in the optimization process of the plasma sources.
The facility consists of three main sub-systems:
•an ultra-high-vacuum apparatus, required to simulate the extra-atmospheric environment, equipped with a 10000 l/s diffusive pump.
•a multitasking acquisition and control system, specifically developed to meet the different experimental issues;
•a diagnostic equipment to perform a wide plasma characterization
.The installed sensors are the following:
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optical spectrometers: measurement of the plasma radiation in the wavelength range 200-1100nm;
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Langmuir probe: measurement of the local plasma density and electron temperature;
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Retarding Potential Analyzer: measurement of the energy of the ejected plasma;
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microwave interferometer: measurement of the plasma density;
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B-field probe: measurement of the magnetic component of the electromagnetic waves emitted by the antenna, both with and without plasma;
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CCD cameras combined with optical filters: detection of the excited ions distribution inside the source and study of the ejected plume divergence
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3D movement system: The vacuum chamber is equipped with slits able to move probes within teh chamber thus allowing a deep characterization of plasma within the plume
The performances of the plasma thruster are affected by several parameter which need to be varied in order to identify their influence on plasma behavior:
•geometrical parameters: plasma source length, outlet diaphragm diameter, injector shape and dimension;
•antenna and power network: antenna type and axial position, matching network, feeding frequency;
•magnetic field: magnetic field intensity and gradients, provided by solenoids or permanent magnets.
The test set-up was expressly designed to allow intense experimental campaign on may different thruster configurations
