The electron cyclotron resonance heating (ECRH) heats (only) the electrons by radio wave heating. The radial position of the resonance layer ist determined by the elctron cyclotron frequency, f = 28 MHz/T. Due to the fact, that the magnietic field decreases with 1/R in a tokamak/stellarator, the ECRH heats the plasma very locally. For our system with a fixed frequency of 140 GHz, the deposition at 2.5 T is located exactly at the minor radius of ASDEX Upgrade.
During the experiments at ASDEX Upgrade the advantage of the local heating is used. The physical studies concentrates on