Thermonuclear instability of FMS modes in tokamak

In recent deuterium experiments on tokamaks Ion Cyclotron Emission (ICE) with frequencies up to 500 MHz have been observed. The spectrum of the oscillations presented regular structure with oscillation amplitude peaked at deuteron cyclotron frequency l harmonics (ω lωBD). The signals of ICE were proportional to the neutron emission which indicates that the ICE could be driven by charged fusion products. Observed bursts of high-frequency (l ∼ 1-10) oscillations in JET, appeared with some delay after the sawtooth crash and coincided with Dα signal on the plasma periphery, which could be explained by the finite time of heat wave generated at sawtooth crash and spread from the plasma center to the periphery. The observed ICE was associated with fusion proton driven Fast Magnetosonic (FMS) waves. In this paper we discuss the problem of FMS eigenmodes excitation by D-D fusion protons generated with superalfven velocity Vp0 = 2.4 109 cm/s. (author) 6 refs., 1 fig