Homopolar Generator as the Energy Store for a Large Laser

THE homopolar generator1,2 at the Australian National University in Canberra can be connected to deliver 1.5 × 106 A at more than 800 V for 0.1 s. When light sources capable of handling such power and energy are developed, it will be possible to use the energy to pump a large laser. We have used the generator with its four disks in series to power a co-axial discharge tube filled with xenon at a pressure of 30 cm of mercury. During a pulse lasting for 7.5 ms we injected 6,000 J/inch into the flash tube which enclosed a Nd glass laser rod 0.5 inches in diameter and 6 inches long. The fluorescent lifetime of the glass is quoted as 360 µs. A record of the radiation intensity is shown in Fig. 1. The decrease in intensity with time was caused by the current being reduced by a variable resistor in series with the lamp, increasing in preparation for the termination of the pulse. If the laser assembly could stand it, a pulse of this power could be supplied for 50 s from the generator.