Motional Stark Effect Measurements of the Local ICRH Induced Diamagnetism in JET Plasmas

Measurements of the toroidal magnetic field inside the JET tokamak plasma by means of the motional Stark effect are reported. In the vicinity of the resonance layer ion-cyclotron-resonance-heating (ICRH) generates a population of energetic ions. For the first time the diamagnetic change in the toroidal magnetic field due to these ICRH fast ions has been measured. A magnetic field decrease up to 4% has been observed. Oscillations of the toroidal magnetic field caused by sawtooth oscillations of the thermal plasma pressure have been resolved. First results of the local-increase slowing-down time of the fast particles are presented.
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JETP93024 1.94 Mb