The electron distribution function in a bumpy torus

New and improved diagnostic techniques and increased theoretical understanding of electron-cyclotron heating (ECH) have led to a new picture of the electron distribution function in the ELMO Bumpy Torus (EBT). For electron energies ≤2 keV, the distribution function can be approximated as consisting of two components: a cold isotropic bulk component and a warm anisotropic tail. For typical steady-state EBT-Scale (EBT-S) operation (microwave power input of 100 to 150 kW) in the T-mode (the operating mode of interest for fusion experiments), bulk densities and temperatures of ne =0.5–0.7×1012 cm−3 and Te ≤100 eV are observed, while the warm tail component has Te =200–800 eV, and densities ≤0.4 that of the cold component. The non-Maxwellian nature of the distribution function is caused by ECH.