On the passage of charged particles through a magnetic field sharply varying in space

The motion of charged particles in a magnetic field which is sharply alternating in space (casp) is theoretically discussed. Found are the conditions in the single-particle approximation under which the transmission of the tubular beam through casp occurs at minimum distortion of the beam characteristics and minimum losses of particles. Also determined was the ultimate degree of deceleration of the longitudinally moving particles at the casp output. It is shown that at a low parameter of the tubular beam a/rsub(o) (a is the Larmor radios, and rsub(o) is the radius of particle escape from a cathode relative to the magnetic field axis), low energy spread and rsub(o) spread a short casp is capable of efficiently converting the translational energy of the tubular beam into the rotational energy and vice versa. In this case the particle density in the beam, which has been preliminarily modulated in density, may increase almost by one order owing to deceleration in the casp