PROPAGATION OF POWER PULSES IN MAGNETICALLY INSULATED VACUUM TRANSMISSION-LINES

The propagation of a 1.8-MV 80-kA power pulse in a 10-m-long 41.6-Ω impedance coaxial vacuum transmission line has been investigated experimentally. The onset of magnetic insulation has been correlated to attainment of the critical current. Measurements of boundary (cathode) current suggest that 50-60% of the current flows in space charge in the axial direction between the conductors. The pulse sharpens as it propagates and attains a stationary shape. Pulse rise times of 4 ns were observed. Propagation velocities equal to 0.7c have been measured. Power and energy transports as high as 90 and 70% have been observed. The peak power density in the transmission line was 2×10 9 W cm-2.