John Scharer

Emeritus Professor


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513 Engineering Research Building
1500 Engineering Drive
Madison, WI 53706

Profile Summary

We also are carrying out 193 nm excimer laser (300 mJ/pulse) creation of high density (1013/cm3) plasmas of large dimension (50 cm long x 20 cm wide x 5 cm thick).The short pulse laser plasma can be then sustained by inductively coupled radiofrequency power.These plasmas have applications as an agile mirror microwave reflector or absorber.Research on radiofrequency sustainment of high pressure atomic and air component plasmas with flow is carried out. These plasmas have important applications in the communications, materials processing and environmental areas. A two-dimensional finite-difference computer code has been developed to describe the antenna coupling, wave propagation and heating of plasmas by these radiofrequency waves.Comparisons with experiments are carried out using state-of-the-art multiprocessor workstations. We have constructed a helicon radiofrequency (1-200 MHz) plasma source steady-state plasma wave facility to carry out wave propagation and heating in an inhomogeneous plasma. The wave amplitude and phase and two-port network analyzer antenna measurements are made, stored, and analyzed utilizing an online computer data acquisition system. The experiment is used to study efficient plasma source production which can be used for a variety of applications. These include submicron etch materials processing, gas processing and simulations of space plasmas. Theoretical, computational, and experimental research is carried out in the areas of radiofrequency plasma sources for materials processing multi-tone experiments and linearized signal processing for broadband travelling wave amplifiers and plasma wave heating for controlled fusion. I also carry out research on excimer laser formation of plasmas and the analysis of and experiments on millimeter broadband wave amplifiers for satellite use. I am also particularly interested in antenna wave coupling, propagation, heating and current drive for the ion cyclotron frequency range (50-200 MHz) in tokamak plasmas. Theoretical formulations and computational research is carried out by a state-of-the-art fiber optics multiprocessor workstation computer facilities to model antenna coupling and plasma heating utilizing radio frequencies and for analysis of gain and nonlinearities in multi-frequency travelling wave amplifiers. The research is carried out by grants from NSF, AFOSR, ONR and DOE. Examples of research currently carried out with graduate students and scientists in our group and with other faculty are indicated as follows:

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