Meet the teams: GRAVARC TNG

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ESA / Education / Spin Your Thesis!

The team is composed of three PhD students from Masaryk University in Brno, Czech Republic. The experiment will examine the behaviour of gliding arcs of plasma in noble gases under hypergravity conditions with the objective of improving our understanding of the physical phenomena involved.

Plasma diagnostics of gliding arc under varying hypergravity

University Masaryk University
Endorsing professor Vit Kudrle
Masaryk University
ELGRA mentor Job Beckers
Eindhoven University of Technology
Team Jiri Sperka, Lucia Potocnakova, Peter Zikan

The team, called GRAVARC TNG, is conducting a similar experiment to the one performed last year by the GRAVARC team during the Spin your thesis! 2012 programme. It means that this year, they have begun with the advantage of an existing baseline. However, with the support of new students, many parts of the experimental setup have been changed or improved, as originally they had a slightly different purpose.

A gliding arc is an electrical discharge which is formed between two or more divergent electrodes with a gas between them. The electrical discharge is formed in the gas, at the smallest gap between these electrodes. The discharge then spreads as it glides along the electrode edges with an increasingly large gap until it dissipates when it clears the electrodes. The dynamics of the gliding arc plasma discharge are partially governed by hot gas buoyancy. Since the strength of the forces exerted by the buoyancy effect varies with gravity, the team expects to observe dynamics that depend on the level of gravity.

Experiment set-up integrated in a LDC gondola
Experiment set-up integrated in a LDC gondola

The main goal of this project is to better understand the processes that govern the glide arc plasma in hyper gravity and in different gases. After analysing the data acquired during experiments in the Large Diameter Centrifuge (LDC) they will find the main parameters in different gravity conditions: the gliding frequency and velocity of the discharge channel, the plasma shape in different gravity conditions, the optical emission spectra also with spatial resolution and the discharge current and voltage waveforms. From the knowledge gained by these parameters for four different noble gases the students will try to correlate the plasma behaviour with gas properties.

The experimental set-up consists of a steel frame containing three platforms. The bottom platform contains the power section of a variable autotransformer (variac), high-voltage transformer, high voltage probe and Rogowski coil current probe. The discharge section includes the discharge chamber itself with copper electrodes, and most of the diagnostics tools. Some of them, like microphone for acoustic measurements and thermocouple are integrated into discharge chamber wooden frame. Also present are fast digital cameras and optical fibres (connected to spectrometer) which will monitor the discharge from close distance. The top section will consist of a computational section that will include oscilloscope and industrial computer. This computer will collect and save the data from multimeters, oscilloscope, microphone and thermocouple.

Read the final experiment report here.

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