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GRAVARC

Hypergravity effects on glide arc plasma

Reseorch of arc discharge in ESA-ESTEC

Project duration: 2012

Project manager: Jiří Šperka

In the project GRAVARC at the Large Diameter Centrifuge at ESA ESTEC team of two PhD students investigated the behaviour of gliding arc discharge in carbon containing atmosphere in conditions of hypergravity as well as the properties of the solid products prepared by plasma enhanced chemical vapour deposition in discharge plasma channel. As the appearance of the glide arc plasma channel in special conditions is governed by hot gas buoyancy, team GRAVARC studied the effects of gravity in the range 1 g – 18 g on the shape, intensity, colour and emission spectra of the discharge. Consequently, the solid carbon deposits produced by the plasma enhanced chemical vapour deposition were also studied. The high speed video of the discharge was recorded by a fast digital camera with 224 x 160 resolution at high frame rate of 480 fps. Optical emission spectra were captured with fixed grating spectrometer Avantes.

The experiment has shown that gravity strongly influences the glide arc discharge, which can be explained by rising thermal buoyancy. In gliding arc, the increasing gravity leads to higher gliding speed of the plasma channel and more complex shape of the channel. The design of the experiment was very flexible - allowing operation with i.e. different electrode materials, various electrode spacing or tilting, with various flow and composition of the working gas. During the experiments only one parameter was remotely controlled - the voltage on the HV transformer primary winding. The other parameters were changed manually from the control room of the centrifuge.

The Department of Physical Electronics

The department makes research and application of low-temperature plasma. Main focus is on research and applications of plasmachemical reactions in non-isothermal low temperature plasma and on interaction of plasma with surfaces of various solid materials. Plasma is studied from both theoretical and experimental points of view. More than 50 years lasting tradition of applied plasma physics research at the Department of Physical Electronics resulted in several innovations successfully transferred into the industry.

What would you name as main benefits of the project to you and your company?

“Thanks to efforts of two PhD students from Masaryk University was established strong link between them and the researchers from Life and Physical Sciences Instrumentation and Life Support Laboratory (LIS) at ESA ESTEC in Netherlands. The main benefit was the opportunity to perform the research in conditions that can be achieved in only a few laboratories in the world. Students got chance to perform precious hands-on activity during Spin Your Thesis campaign getting used to the specifics of space instrumentation and space project documentation basics.”