Study of high-β plasma stability and transverse loses in the experiments on modern magnetic mirrors

The paper reviews recent results obtained the experiments on the modern magnetic mirrors in Novosibirsk. An emphasis was made on studies of plasma transverse losses and stability in the regimes with maximal plasma beta. The experiments were carried out on the multiple mirror device GOL-3 and gas dynamic trap (GDT). Both devices are characterized by axial symmetry and improved axial confinement of plasma compared to conventional mirror machines [1-4]. Observed plasma activity in the GDT is thought to be related to both high anisotropy of fast ion component produced by 25keV, 5MW neutral beam injection and high plasma beta approaching 60%. This activity however does not result in considerable increase of plasma energy losses, which are dominated by axial collisional losses through the end mirrors. In the GOL-3 device, in which plasma is heated by axial injection of a relativistic electron beam, excitation of large amplitude plasma turbulence also does not considerably increase radial plasma losses, so that the axial ones are always dominate energy balance.