Investigation of plasma heating by powerful relativistic electron beams

The results of investigations on plasma heating by relativistic electron beams, conducted at the Institute of Nuclear Physics, which are an integral part of the programme of investigating the possibility of creating a thermonuclear reactor based on solenoid systems, are outlined. The results of experiments on the interaction of high-current relativistic electron beams and a plasma, carried out on the GOL-1 and INAR devices, are presented. - Experiments on beam transport in a plasma (nsub(e) approximately equal to 1014cm-3) in two magnetic-field configurations: homogeneous (L=7.5m) and multi-mirror (L=3.5m), were carried out on the GOL-1 device. No macroscopic beam instabilities were found. The interaction of the beam with the plasma was investigated simultaneously with the beam transport (nsub(e) approximately equal to 1014cm-3 and H0=13kOe). Approximately 5% of energy per metre is released in the plasma at jsub(b)=1kAcm-2. - A series of experiments was carried out on the INAR device, whose purpose it was to clarify the possibility of heating a plasma with a density of n approximately 1015cm-3. It is shown that a decrease in the angular spread of the injected beam by reducing the thickness of the input foil and also the use of a strong magnetic field lead to an increase in the energy release in the plasma column; the most effective heating is observed, in this case, at the beam input into the plasma. At H0=25kOe,jsub(b)=1kAcm-2 and at an input foil thickness of 6μm(Ti), the relative beam energy losses in a plasma with density of n=4x1014cm-3 amounted to 20% on a length of 240cm. A plasma heating efficiency of 10-15% of the total beam energy at a density of n=3x1015cm-3 was achieved with an increase in the beam current density of up to 5kAcm-2. The strong dependence of the energy release in the plasma on the angular beam spread as well as its non-uniformity over the length of the device indicate that a beam instability should play the main role. (author)