The simple magnetic configuration of mirror traps allows for the efficient mechanism of plasma heating by powerful electron beams. The energy of plasma oscillations driven by the injected beam is transferred to the dissipation region of turbulent spectrum due to various nonlinear processes and eventually absorbed by plasma particles. As the turbulence energy increases, generation of electromagnetic waves near the plasma frequency and its second harmonic comes into play.
Since the high-current relativistic electron beams employed in laboratory experiments at the GOL-3 multi-mirror trap at the Budker Institute of Nuclear Physics (Novosibirsk, Russia) are powerful enough to provide a strong pump of excited turbulence, the question arises whether a mirror-like machine can be used for generation of high-power electromagnetic radiation in the terahertz frequency range. This kind of radiation could be potentially useful for a number of applications in medicine, energy transmission, security systems, and radar installations.
Calculations show that in the region of most intensive beam-plasma interaction, the power of the second harmonic plasma emission generated due to coalescence of upper-hybrid waves inside the most energetic part of turbulent spectrum can reach the level of 1MW/cm3, which corresponds to 1% conversion efficiency of the beam energy losses into electromagnetic emission. These calculations are in a good agreement with the results of existing experiments operated in a low plasma density regime and will have a significant impact on the future works aimed at construction of a new type of electromagnetic generator, in which the radiation frequency can be easily varied just by tuning the plasma density.
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