ION CYCLOTRON INSTABILITIES IN THE PHOENIX APPARATUS

摘要

Instabilities which are associated with bursts of electrostatic oscillations at, or near, the ion cyclotron frequency and its harmonics are present in the PHOENIX machines both in the simple mirror and in the quadrupole magnetic well configurations. In both cases the instability is accompanied by energy spreading of the initially monoenergetic ion energy distribution though the effect is less marked in the latter. The fields have been resolved into those generated by azimuthal and axial currents and the frequency spec¬trum of each component has been measured. In the simple mirror the strongest signals are generated by m = 1 azimuthal currents which show characteristic frequency sweeps starting at the ion cyclotron frequency corresponding to the centre of the machine and falling by some 10％ in the duration of a burst.