טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentYang Cao
SubjectCharacterization of the Plasma Source for Plasma
Wakefield Research
DepartmentDepartment of Physics
Supervisor Full Professor Krasik Yakov
Full Thesis textFull thesis text - English Version


Abstract

We characterize a novel plasma source, based on surface flashover along a dielectric surface of a multi-gap structure, for an experiment where wake-field generation in a plasma filled waveguide by a high-power microwave pulse will be studied. The plasma parameters were studied by a fast-framing intensified camera, a single Langmuir probe, an array of Faraday cups, microwave cutoff and microwave interferometry and spectroscopic diagnostics methods. We found that the parameters of the plasma thus formed are suitable to those required for the wake-field generation experiments. The results enable the description of the dynamics of the plasma formation and the thermal evolution of the plasma source. We also characterized the plasma formed by a 1 ns, 200 MW, microwave (9.96 GHz) beam when it interacts with air and He gas at various pressures. This is important in experiments where the microwave pulse is focused rather than traveling in a waveguide. For this study, we used a fast-framing intensified camera, microwave transparency measurements, microwave pattern measurement and absolute calibration of the He spectral lines. The images obtained by the fast-framing intensified camera, reveal unique dynamics, suggesting that the plasma thus formed by the focused microwave beam, channels it along the experiment axis and causes self-focusing. This channeling effect is also supported by the light pattern obtained on a surface filled with a neon lamp array. Microwave transparency experiments show the dependence of the transparency on pressure.  From absolute calibration of the He spectral lines, the plasma density was determined to be 1012 - 1013 cm-3.