Pustarex, the electron ring accelerator experiment at Garching

Preliminary results of experiments carried out at the Pustarex are reported. It is shown that experimental data fit very well the calculated behaviours of the magnetic field index. In the experiments with the squirrel cage structure magnetic probe signals are shown during different compression stage. It is shown that resistive wall instability, high rf-activity and strong electron losses occurred and 4x1012 electrons in a ring 18 cm in radius are trapped. In the experiments without squirrel cage 6-8x1012 electrons are trapped and compression of the ring to a major radius of 1.6-1.8 cm and a minor radius of 0.5 cm was conducted. The results of investigations of a field emission cathode are given