The hollow-charge effect in the cathodic plasma jet under vacuum breakdown

It is shown that the rapid pinching of the cathodic plasma jet by its own magnetic field causes the ions to accelerate and to increase their kinetic energy from epsilon(0) similar or equal to 10(2) to epsilon similar or equal to 10(3)-10(7) eV if the current enhancement occurs before the plasma jet has reached the anode. This process is quite similar to that of fast jet formation from the collapse of a cylindrical metal liner driven by converging detonation waves. Energetic ions may be produced only in Delta t = Delta l/V-0 after the onset of breakdown of the vacuum, with V-0 similar or equal to 10(4) m s(-1) being the velocity of the unpinched plasma jet and Delta l similar or equal to 1-5 mm the distance from the cathode at which the magnetic pressure becomes similar to the kinetic pressure of the plasma.