Heating of Plasma Electrons by Laser Radiation under Parametric Resonance Conditions in Strong Magnetic Field
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MA HEATING
Heating of Plasma Electrons by Laser Radiation under Parametric Resonance Conditions in Strong Magnetic Field V. B. Krasovitskiya,* and V. A. Turikovb,** a Keldysh b
Institute of Applied Mathematics, Russian Academy of Sciences, Moscow, 125047 Russia Peoples’ Friendship University of Russia (RUDN University), Moscow, 117198 Russia *e-mail: [email protected] **e-mail: [email protected] Received September 18, 2018; revised November 22, 2018; accepted November 22, 2018
Abstract—Heating of plasma electrons by an extraordinary laser wave at the double upper hybrid frequency in a strong magnetic field is studied numerically by the particle-in-cell method. It is shown that, in this case, significant heating takes place even at considerable detunings from the fundamental parametric resonance. This makes it possible to reduce the resonance magnitude of the magnetic field. The minimum value of the laser field amplitude at which parametric heating of this type can be implemented is found. DOI: 10.1134/S1063780X19050064
1. INTRODUCTION The interaction of high-power laser radiation with dense plasma is accompanied by the generation of superstrong quasistatic magnetic fields. Interest in studying such processes has significantly arisen in recent years in connection with the appearance of ultrarelativistic laser sources. A vast literature on this problem was presented in the survey [1]. Magnetic fields observed experimentally in the region with the critical plasma density reached several hundred megagausses [2]. The effect of strong magnetic fields generated in laser-produced plasma on the process of electron acceleration up to relativistic energies in the field of a plane wave was studied in [3]. The resonance interaction of high-power laser radiation with plasma in a strong magnetic field leads to the excitation of largeamplitude nonlinear plasma oscillations [4–7]. Strong magnetic field in plasma can also be created in the Z-pinch neck. The effect of laser radiation on such plasma was considered in [8]. In the experiments carried out at the NTF facility [9], high-power laser radiation at the fourth harmonic of the fundamental frequency (λ0 = 1064 nm) was used to diagnose the pinch interior. In this context, it is of interest to find out whether it is possible to additionally heat Z-pinch plasma at such laser frequencies. In this work, the mechanism of electron heating by an extraordinary laser wave in the region of the fundamental parametric resonance at the double upper hybrid frequency is studied by numerical simulation. This mechanism of
plasma heating is widely used in magnetic confinement systems. However, the amplitudes of heating radiation in such systems are much lower than the amplitudes of radiation generated by present-day high-power lasers. Therefore, it is important to study the influence of nonlinear effects on the dynamics of parametric instability at such high amplitudes. 2. PARAMETRIC INSTABILITY OF COLD PLASMA IN THE FIELD OF AN EXTRAORDINARY LASER WAVE Let us consider the parametric action of a
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