Title screen

[References: 22 tit.]

The dynamics of propagation of the virtual cathode (VC) during the collective acceleration of protons in the Luce diode has been measured by observing prompt signals of electron currents emitted by the VC with a series of five collimated sensors set normally along the diode axis, as well as by recording signals of Bremsstrahlung and �-rays generated in a B4C target placed at 25 cm distance from the anode. It has been found that the VC, after the acceleration phase to the optimal distance of about 12 cm, further propagates in the direction of the target with a nearly constant velocity. It has been shown that the generation of the high-energy �-rays in the target corresponds to the moment the VC arrives at the target position, which indicates the acceleration of protons by the VC and the synchronism of their joint motion. It has been proposed that the acceleration of the VC towards the target is mainly due to the ionization of the residual atmosphere of the drift chamber by the accelerated protons. The ionization efficiency decreases with an increase in the energy of the accelerated protons, which ultimately limits the possibility of their further acceleration.