MWPlasma

“Microwave semiconductor driven plasma sources of high power ranges for plasma generation”

Summary

For industrial generation of microwaves, particularly at high power levels, magnetron tubes are commonly used today. Tubes operating at a frequency of 915 MHz are employed. Due to manufacturing tolerances of the magnetron tubes, the microwave frequency can vary by several tens of megahertz. In addition, tolerances in the mechanical components of the plasma sources can cause shifts in the resonance frequency of the plasma system. Moreover, depending on the specific application, the plasma itself can influence the resonance frequency.

While this is negligible for industrial microwave heating, it becomes significant in the excitation of microwave plasma sources that are based on resonant structures. Typically, these deviations are compensated by tuning elements. In contrast, solid-state microwave generators offer the advantage of being able to adjust the excitation frequency accordingly.

The service life of high-power magnetron tubes typically ranges around 10,000 hours, and their operating frequency can drift slightly over time. For high-value processes such as diamond film deposition (with process durations of 200–300 hours), longer lifetimes are of great interest, since a system failure during operation can easily result in losses on the order of €100,000.