A single-shot method for measuring the energy spectra of pure electron plasmas driven by E × B rotation

In this study, a new single-shot method is developed for obtaining the parallel energy spectra of pure electron plasmas that rotate around the machine axis by the E × B drift. When the confinement voltage is raised to the ground level on a timescale that is comparable with the E × B rotation period, the electrons escape from the confinement region along the magnetic field lines over the potential barrier and onto a phosphor screen in the descending order of the energy of the electrons. This causes the phosphors to emit light at different points on the screen along the E × B rotation trajectory depending on the electron's energies. Further, the energy distribution can be derived from the luminosity distribution along this trajectory by appropriately converting these positions into their corresponding energy levels. (author)