Cold-Cathode Magnetron Gun with a Beam Current More than Kiloampere in Self-Supporting Secondary Emission Mode at Relativistic Voltage

High power magnetron injection gun with voltage up 1000 kV was calculated, designed and manufactured. The gun was tested in nanosecond and microsecond operating modes. The application of nanosecond voltage pulses with amplitude up to 600 kV permitted to obtain the secondary-emission current up to 4 kA. The cathode testing in microsecond mode permitted to obtain beam pulse with amplitude up to 1.2 kA at voltage of 400 kV in magnetic field of 0.3 T. There were obtained beam traces on the copper plate. Traces had the form of rings with diameter of 125 mm and width of 5 mm. The secondary emission nature of the cathode current up to 4 kA and beam current up to 1.2 kA was established. The identification was held basing on considered features of the exciting and on the maintenance of the secondary emission current. However, there is the probability of the parasitic explosive emission at extremely high voltage values since 800 kV.