Plasma Research at UW-Madison
Professor John Scharer and his research group at UW-Madison have been conducting research on plasmas since 1978. He has published over 100 journal articles and contributed to the fields of fusion plasmas, laser induced plasmas, helicon plasmas and many other areas.
Several recent Scharer group publications highlight results from our main research areas:
Laser Produced Plasmas
The Laser Produced Plasma Facility uses a high power flux (10 TW per square centimeter) excimer laser operating in the argon-fluoride mode (6.4 eV per photon, 193 nm) to investigate laser breakdown of air at pressures from 5 atm down to 50 torr. A recent publication [Thiyagarajan 2008b] shows laser breakdown follows the same scaling as high power microwave breakdown as well as examines laser breakdown shockwave dynamics using shadowgraphy. Thiyagarajan 2008a investigates density and electron temperature evolution during laser breakdown and compares results to the SPECAIR code.
RF Air Plasmas
Up to 25 kW of 13.56 MHz RF power is available to create seeded air and nitrogen plasmas. Luo 2008 investigates laser initiation and RF sustainment of plasmas at pressures up to 760 torr with a low power budget (5 W/cc).
The Madison Helicon Experiment (MadHeX) is capable of up to 10 kW operation (13.56 MHz) at flowrates as low as 1sccm. Recent experiments have culminated in a publication [Denning 2008] highlighting exciting results concerning the effects of neutral depletion on plasma flow and pressure balance in helicon plasmas.