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Abstract
The investigation of the dynamics of coaxial plasma accelerator
system for its use as a source of microwave radiation in gyrotron mode is
of interest. A simulation model of microwave emissions of gyrotron type
has been designed and was in agreement with experimental results. The
findings of this study showed that the emission of microwave has a
starting condition, which is markedly depends on sheath velocity of
rotation around the axis of discharge. i.e. it depends on gas density and
driving Lorentz force.
The introduction of a. magnetization coil provides a strong axial
magnetic field driving a radial force, which in turn acts upon the coaxial
accelerator current sheath and forces it to rotate around the axis of
discharge electrodes. As a result of the current sheath fast rotation inside
the magnetic field, wave emission in the range of microwave frequencies
is produced. This hypothesis is investigated experimentally on two
accelerator discharge chambers having contrast aspect ratios. Theoretical
modeling describing this wave emission as a result of current sheath
rotation around the axis is analyzed and comparison of the model results
with experimental results is illustrated.
The validity of the Lee simulation model for coaxial discharge
geometries IS investigated: experimentally on the two electrode
configurations (apparatus A and apparatus B). The results of
photomultiplier tubes detection of the time of arrival of luminous area of
the current sheath are compared with the simulated results. The simulated
sheath dynamics model results are used in theoretical representation of
the wave emission described in the derived analytical model. Results of
the model showed a time-band of wave emission for case of 3-cm 10-
GHz waves in the microwave region occurring at ranges of charging
voltage and gas p.essure.
Experimental results of 3-cm 1 O-GHz wave emission for inspected
ranges of charging voltage and gas pressure are compared with theoretical
results, showing that experimental results of time of occurrence of wave
emission are In agreement with results calculated from the derived
analytical model.