Experiments on ICRH at the end system of AMBAL-M

Results of experiments on ICR-heating of hot initial plasma at the end syst em of AMBAL-M are reported. The heating is performed by an antenna of "Nago ya-III" type installed in the transition region between the mirror and the semicusp. Varying the magnetic field strength in the mirror it was found th at the plasma heating in the mirror occurred both at the first and at the s econd frequency harmonics. The heating does not result in any detectable di stortion of the azimuthal symmetry of the initial plasma. The experiments w ith a small radius of the initial plasma allowed to determine coefficient o f diffusion arising in result of RF heating. Measurements of the RF fields spectrum in the plasma demonstrated the emergence of the second frequency h armonic. At the limiting ICR-heating power it was found that after the pulse of the initial plasma created by the gas-discharge source, the steady-state plasma with duration of 40 ms was sustained in the mirror during RF-power input. The steady state plasma is fed by hydrogen puffing arising in result of con siderable recycling. The steady state plasma has the density similar to 10( 12) cm(-3), electron temperature similar to 40 eV, ion energy 300-400 eV.