The features of the characteristic electromagnetic plasma bunches oscillations in the long magnetic mirror

The aim of this work was to study the spectrum of LF and HF oscillations generated by plasma bunches created and confined in the volume of a microwave cavity immersed in the magnetic field of a mirror trap. The registration of electrostatic oscillations in the plasma was carried out using two flat electrodes mounted diametrically opposite in the central part of the cavity close to its wall. This diagnostic showed the presence of low-frequency oscillations with frequencies of 130 kHz and 450 kHz. The oscillation spectrum in the microwave range was recorded at the minimum of the magnetic trap using a real-time spectrometer and a loosely coupled loop antenna. The registration of the spectra in the 40 MHz band revealed a regular change in the frequency of the fundamental oscillation mode of the cavity and the presence of two harmonics of the synchrotron radiation of the plasma bunch at frequencies of 2.25 GHz and 4.52 GHz, respectively. According to the obtained data, the parameters of the formed bunch (density, shape, volume, energy spectra of plasma components) can be restored.

Расчет и анализ электрофизических процессов в мощном импульсном ускорителе плазмы с собственным магнитным полем

We have considered basic theoretical models describing various aspects of the formation and acceleration of plasma in pulsed accelerators. The discharge current, magnetic field, and plasma bunch velocity have been determined experimentally at different initial gas pressures in the accelerator chamber. We have considered the correspondence of some theoretical models of plasma acceleration to experimental data obtained in a KPU-30 coaxial accelerator. It is shown that the formation of the plasma in the coaxial accelerator depends on the plasma density, and acceleration processes at densities higher and lower than a certain transient density value on the order of 10^11–10^12 cm^–3 are different. At a density higher than this critical value, the plasma is accelerated by a magnetic force. At the same time, at a low plasma density, plasma can be accelerated by an internal electric field.