Examine now the particle motion in curved magnetic field. If a particle moves along a curved line or spirals around a force line, the centrifugal force p 2 c2 H
arises. The force will result in a drift in the direction perpendicular to the plane comprising the given section of the force line:
1.10.7. Traps with a magnetic field varying along the force lines
The case is of great interest where the field intensity varies along the force lines (in this case the force lines are not parallel) and the Lorentz force component parallel to v// appears. In connection with this, the field-aligned particle energy varies and, since the total particle energy remains constant in stationary magnetic field, the transverse component of momentum should also vary. Since in the case of motion towards a stronger field the Lorentz force component is directed opposite to the motion, the longitudinal momentum decreases and may even vanish. In this case the particle will move with acceleration in opposite direction, reflection from the sector with stronger field will occur. It can be easily shown (see, for example, in Pikelner, M1961) that if the field inhomogeneity is weak, magnetic moment M is conserved. From this, it follows from Eq. 1.10.8 that the value sin2 e/H = const (1.10.14)
is conserved during the particle motion. A particle with angle 6 to the field at point with intensity H will be reflected at a point where e =n/2, and the field intensity
H' = h/sin2 e. It can be seen from the above that the smaller the initial value of 6 the more intense a field the particle will penetrate. Such reflection region is essentially a magnetic mirror. The particles, in moving between the magnetic mirrors, will be confined within the trap.
1.10.8. Traps with a magnetic field varying with time
It is of great interest to examine the case of particle motion in a magnetic field whose intensity varies with time. Consider a small region of the space where the field may be treated as homogeneous. Under the influence of the induced electric field and as the magnetic field intensity increases, the particles will drift towards the OZ axis at velocity dr/dt = -(1/2)rH/H, (1.10.15)
The existence of the regions with magnetic field inhomogeneities and the collisions of CR particles with plasma particles will result in particle scattering, diffusion across the field, and, ejection from the traps.
1.11. Cosmic ray interactions with electromagnetic radiation in space plasma
1.11.1. Effects of Compton scattering ofphotons by accelerated particles
The Compton effect on relativistic electrons (or, as it is called, the 'inverse' Compton effect) has been studied in many works. The first efforts in this direction were made by Feenberg and Primakoff (1948) in connection with the problem of whether the CR may have the electronic component. It has been shown in (Felten and Morrison, 1963; Ginzburg and Syrovatsky, M1963) that the Compton effect of thermal photons by electrons of CR of galactic origin may make certain contribution to the isotropic y-ray background. Gordon (I960), Shklovsky (1964a), Zheleznyakov (1965), Korchak (1965a,b) studied the possible importance of the inverse Compton effect of thermal photons on the electron component of solar CR to generation of X-rays and y-rays in solar flares. Ginzburg (1964) and Shklovsky (1964b) estimate the possible contribution from the inverse Compton effect to the generation of electromagnetic radiation from various radio objects. Korchak and Ponomarenko (1966) have calculated the expected spectrum of photon emission generated by the inverse Compton effect in interactions between accelerated electrons and isotropic background of thermal photons. In this case Korchak and Ponomarenko (1966) proceed from the formula for Compton cross section (Akhiezer and Berestetsky, M1959):
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