Group leader: Dániel Dunai
The website od the group: wigner.mta.hu/beam_emission_spectroscopy
The Beam Emission Spectroscopy (BES) experimental technique has been used in fusion plasma experiments for decades. Nearly all major fusion experiments are equipped with BES diagnostics, and a variety of applications have been developed. The basic idea is that an atomic beam can penetrate the magnetic field of fusion devices and the beam fluorescence is measured. The light emission originates from excitation by plasma particle collisions; hence the light intensity gives information primarily on local plasma density.
Principle of the beam emission spectroscopy diagnostic
Light rays in and port structure of EAST alkali beam diagnostics
Transport of energy and particles in magnetic fusion devices is mostly driven by small-scale turbulence. Fusion plasma is a self-regulating system, where parameter profiles drive the small turbulence and turbulence sets the parameter profiles. Additionally turbulence itself is regulated by self-generated flows. BES diagnostics are capable of measuring all 3 elements: the plasma density profile, the ion scale (cm) turbulence structures, and through their movement the flows. The temporal resolution in these experiments is typically 1 microsecond, the spatial resolution is cm.
Our group designs, manufactures, installs and operates BES diagnostics in several major fusion devices around the globe. Heating beam BES diagnostics were installed at MAST, KSTAR and EAST tokamaks, while alkali beams are operated in collaborations at JET, KSTAR, EAST, Compass and ASDEX Upgrade tokamaks. Wendelstein 7-X stellarator is also being equipped with an alkali beam BES diagnostic. This diversity gives a unique opportunity for multi machine comparison of several important physics phenomena.
BES diagnostics built and partly operated by the members of the BES research group around the world .