A one-dimensional study of the evolution of the microwave breakdown in air

Abstract

The microwave breakdown in air is simulated numerically within a simple 1D model taking into account a perturbation of electromagnetic field by plasma. The simulations were performed using two qualitatively different codes. One of these codes is based on computation of Maxwell equations, whereas the other one utilizes an approximation of quasi-monochromatic electromagnetic field. There is a good agreement between simulation results obtained by using both codes. Calculations have been carried out in a wide range of air pressures and field frequencies; also varied were initial spatial distributions of plasma density. The results reveal strong dependence of the breakdown evolution on the relation between the field frequency and the gas pressure as well as on the presence of extended rarefied background plasma. At relatively low gas pressures (or high field frequencies), the breakdown process is accompanied by the stationary ionization wave propagating towards the incident electromagnetic wave. In the case of a high gas pressure (or a relatively low field frequency), the peculiarities of the breakdown are associated with a formation of plasma filament array. The extended background plasma can suppress formation of the plasma filament array completely even at high pressures (or low frequencies).

Discharge from a high-intensity millimeter wave beam and its application to propulsion

“…Semenov et al conducted a 1D plasma fluid simulation coupled with Maxwell's equation to examine the effects of the incident electromagnetic wave intensity, incident microwave frequency, and the background plasma profile on the microwave plasma formation [79,80]. A 1D plasma diffusion equation was numerically integrated using a simple diffusion coefficient instead of using the effective diffusion coefficient.…”

Joule-heating-supported plasma filamentation and branching during subcritical microwave irradiation

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] In recent years, a plasma filamentation was reported to occur during microwave irradiations. Hidaka et al 1 experimentally obtained a filamentary plasma by lens focusing of the microwaves generated by a pulsed 1.5 MW, 110 GHz gyrotron.…”

“…In a number of studies, numerical simulations using a fluid or particle model coupled with electromagnetic wave propagation were conducted to reproduce the self-organized pattern observed under the overcritical condition. [8][9][10][11][12][13][14][15][16][17] In these simulations, instead of solving the beam-focusing process by the lens, the rms electric field of the incident beam (E 0,rms ) was set to be above E c to reproduce the plasma formation sustained by the overcritical field at the focal point. The simulation results indicate that a quasi-standing wave is induced in front of the plasma because microwaves reflected by the dense plasma overlap the incident microwave.…”

A possibility of remote detection of air breakdown in a focal spot of microwave beam using reflected signal

“…The breakdown delay time, as well as the plasma parameters, is sensitive to existence of radioactive materials which can ionize air producing thereby seed electrons in the vicinity of the breakdown prone volume [1][2][3]. Therefore a study of the breakdown evolution can give some particular information about the closeness of radioactive materials to the focal spot of high power microwave beam [3,4].…”