University of Wisconsin-Madison Physical Sciences Lab

Flashlamp Power Supplies Undergoing Final Tests

Thursday, August 19th, 2010

Late in 2006, the UW Physics department asked PSL electrical engineers to design and build a series of flashlamp power supplies for a novel laser system on the Madison Symmetric Torus (MST). The power supplies are complete, installed, and in their final phases of test.

Twenty power supplies were constructed, allowing 20 powerful flashlamps to be fired simultaneously. The lamps power 6 laser amplifier stages, increasing laser beam energy over 10 million times. The power supplies are independently programmable for flashlamp brightness and pulse duration, and can generate electrical pulses of up to 1800V at 2000A.

Lasers are used on the MST to measure critical properties of the plasma, utilizing a phenomenon called Thomson Scattering. Currently, some of the supplies are powering older flashlamps in an existing Thomson Scattering laser system. However, all the power supplies will eventually be used to drive a new laser system called Fast Thomson Scattering. This new system can measure changes in the plasma that occur too fast for the older system to detect.

The Fast Thomson laser system is nearly complete and is being tested with power supplies not currently in use with the older system. Some problems have surfaced, especially the discovery that inductive spikes have pushed the power supply switches (IGBTs) over their voltage limit. A method to squelch the spikes has been designed and tested successfully. Final tests of all power supply systems are now underway.

This project is funded by the Department of Energy.