Time-resolved optical-emission spectroscopy measurements are used to evaluate plasma density in an interference switch during the extraction of a nanosecond output pulse from a high-power microwave compressor. The compressor represents a resonant cavity connected to an H-plane waveguide tee with a shorted side arm filled with helium at a pressure of 2 • 10 5 Pa; the plasma discharge in the tee side arm is triggered by a Surelite laser. A nanosecond-scale dynamics of the plasma density is obtained by analyzing the shape of the helium spectral lines. The analysis of the experimental data evidences a correlation between the rise time of the plasma density and the peak power of the microwave output pulse. Numerical simulations of the microwave energy release from the cavity with the appearance of the plasma yield results in good agreement with the measured output pulse peak power and waveform.
Numerical simulations of the process of electromagnetic energy release from a high-power microwave pulse compressor comprising a gas-filled cavity and interference switch were carried out. A microwave plasma discharge in a rectangular waveguide H-plane tee was modeled with the use of the fully electromagnetic particle-in-cell code MAGIC. The gas ionization, plasma evolution, and interaction with RF fields accumulated within the compressor were simulated using different approaches provided by the MAGIC code: particle-in-cell approach accounting for electron-neutral collisions, gas conductivity model based on the concept of mobility, and hybrid modeling. The dependences of the microwave output pulse peak power and waveform on parameters that can be controlled in experiments, such as an external ionization rate, RF field amplitude, and background gas pressure, were investigated. V C 2014 AIP Publishing LLC.
Resonant microwave pulse compressors producing output pulses of megawatt-to-gigawatt peak power with high (tens and hundreds) power gain operate at high pressures of a background gas filling a compressor's cavity and switch 1 . Meanwhile, at present, there is no clear understanding of processes governing the plasma formation and ultimately determining the output power in such compressors. In this work, numerical simulations of the microwave energy release from a compressor comprising a gas-filled cavity and interference switch were carried out. The plasma discharge in a switch in a waveguide H-plane tee was modeled using the code MAGIC 2 . Gas ionization, plasma evolution and interaction with RF fields accumulated within the compressor were simulated using different approaches provided by MAGIC: particle-in-cell approach accounting for electronneutral collisions, gas conductivity model based on the concept of mobility, and hybrid modeling. The dependences of the microwave output pulse peak power and waveform on parameters that can be controlled in experiments, such as the external ionization rate, RF field amplitude, and background gas pressure, were investigated. Results of these simulations will be presented.
The evolution of the light emission from the plasma, which is formed to release the microwave energy from the S-band pulse compressor, was studied using fast-frame (2 ns) optical imaging with a 4QuikE intensified camera. The compressor comprised a cavity filled with pressurized air at up to 3⋅10 5 Pa pressure and an H-plane waveguide tee as an interference switch; it generated output pulses of ~8 ns duration and up to 7.4 MW peak power in 2.766 GHz frequency. The plasma discharge in the switch was triggered by a Surelite laser. From the imaging data, the typical size of the plasma and the velocity of its expansion along the RF electric field were determined and the plasma density was estimated. The influence of the plasma time-and space evolution on the power and waveform of microwave output pulses observed in the experiments was determined in numerical simulations. Simulations showed a good agreement with measurement results in terms of output pulse rise time and efficiency of the microwave power extraction.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.