Plasma heating using strong turbulence and relativistic electron beams

A mirror-confined plasma column (plasma density nsub(p)<=6x1013 cm-3) has been heated by current-driven turbulence and by the injection of a relativistic electron beam along the magnetic field. In experiments performed with low-current beams (beam current I<=21sub(A)=2x17 kA) the energy per electron-ion pair transferred to the plasma increased linearly with the beam to plasma density ratio nsub(b)/nsub(p). In these experiments the electron heating is attributed to the electron-electron beam plasma interaction while the energetic ions are probably produced by an electrostatic acceleration. After heating, the plasma column oscillates radially with a frequency ω proportional to the Alfven velocity (ω proportional to B nsub(p)sup(-1/2) where B is the confining field). At the higher plasma densities, energetic confined electrons were detected, and are attributed to interactions with waves propagating at large angles to the beam. (author)