On the Charged Particles' Acceleration in Crossed Fields

The analysis is based on the relations characterizing charged particles' motion in the drift approximation (D. V. Sivukhin, inReviews of Plasma Physics,Ed. by M. A. Leontovich (Consultants Bureau, New York, 1965), Vol. 1, p. 1; B. A. Trubnikov,Introduction toPlasma Theory(Mos. Inzh. Fiz. Inst., Moscow, 1968) [in Russian]). It is noted that the particles can be accelerated using the device proposed in the work (A. V. Timofeev, Sov. J. Plasma Phys.4, 464 (1978)) for the inverse process of converting the particles' chaotic motion energy into electric energy. The magnetic field of such a system is similar to that of the rectilinear current-carrying conductor. In the work (A. D. Beklemishev, Phys. Plasmas22, 103506 (2015)), for particle acceleration, it was proposed to use the magnetic field, which is the superposition of the homogeneous field and the helical field with a varying period. In such a system, the charged particles' acceleration can be considered to be the result of the Cherenkov resonance interaction of particles with the zero-frequency electric field. During the particles' acceleration, the resonance conditions can be maintained due to the autophasing process, which is a consequence of the constancy of the corresponding adiabatic invariant (A. I. Neishtadt and A. V. Timofeev, Sov. Phys. JETP66, 973 (1987)). To ensure these conditions, the helical field period should vary quite slowly along the system's axis.