Electromagnetic radiation generation is an inseparable property of fusion plasmas, acting as one of the major energy sinks. This is caused by the mean free paths of photons, which can escape the majority of fusion plasma regimes without collisions and absorption . The properties of the escaped photons are given by the plasma properties and force fields and thus carry outside valuable information about its state. Visible light spectroscopy is field oriented on utilising this radiation to estimate properties of plasma. One of the drawbacks is the bad spatial localisation of measurements. To overcome this, spectroscopy uses a wide variety of measurement and data science techniques.
Recently it was agreed that part of the spectroscopic instrumentation previously used at the COMPASS tokamak will be transferred to GOLEM. It consists of single channel overview spectrometers, a high resolution multi-channel spectrometer and optical equipment allowing multi-channel measurements at the tokamak side. The aim is to enhance the capability of spectroscopic measurements of GOLEM.
The goal of this work is to put the listed system into operation. This includes getting familiar with the instrumentation and learning how to prepare and control the diagnostic during experiments. This includes for example alignment and calibration procedures and also management of spectra measured during GOLEM experiments and their subsequent analysis. If the instrumental part of the work is successful, the student can attempt to estimate plasma properties from the measured spectra, for which a familiarity with processes and conditions, leading to their generation, is needed.
The nature of this work is weighted more on the instrumental part of scientist’s work and thus is suited more for experimentally oriented students. The skills gained by working on this topic include getting experience with spectroscopic instrumentation and operation of diagnostics on a fusion device and also learning some entry-level programming skills to perform simple data analysis.
The expected language of the thesis is English, but the supervisor is capable of communication in both Czech and English languages.
Outline:
- Familiarisation with spectroscopic instrumentation transferred from COMPASS to GOLEM.
- Installation of selected spectroscopic diagnostics on GOLEM
- Operation and measurement with the diagnostics during GOLEM experiments
- Analysis of the measured spectroscopic signals
Literature:
- SALZMANN, David. Atomic physics in hot plasmas. New York: Oxford University Press, 1998. International series of monographs on physics (Oxford, England), 97. ISBN 0195109309.
- HUTCHINSON, I. H. Principles of plasma diagnostics. 2nd ed. New York: Cambridge University Press, 2002. ISBN 0521803896.
- Lomanowski, B.A., Meigs, A.G., Sharples, R.M., Stamp, M., Guillemaut, C. and Contributors, J.E.T., 2015. Inferring divertor plasma properties from hydrogen Balmer and Paschen series spectroscopy in JET-ILW. Nuclear Fusion, 55(12), p.123028.
- Henderson, S.S., Bernert, M., Brezinsek, S., Carr, M., Cavedon, M., Dux, R., Gahle, D.S., Harrison, J., Kallenbach, A., Lipschultz, B. and Lomanowski, B., 2019. An assessment of nitrogen concentrations from spectroscopic measurements in the JET and ASDEX upgrade divertor. Nuclear materials and energy, 18, pp.147-152.