Measurements of Energy of Hydrogen Atoms Penetrating into Plasma from Vacuum Chamber Wall of the L-2M Stellarator in Ohmic Heating Regime

The energy of hydrogen atoms penetrating into the plasma after being desorbed from the vacuum chamber wall of the L-2M stellarator in the ohmic heating regime was measured based on the Doppler broadening of the Hα line; this energy turned out to be equal to 4.1 eV. Penetration of hydrogen atoms with the energy measured into the plasma was simulated, and energy spectra of the flow of neutrals escaping from the plasma were calculated. The results obtained were compared with the results of similar calculations performed at the 2-eV-energy of atoms penetrating into the plasma. The 2-eV-energy is conventionally used in such simulations. It was shown that changing the energy of neutrals coming from the vacuum chamber wall strongly affects penetration of neutral particles into the central plasma regions. Simulations showed that at a particle energy of 4.1 eV, the number of neutral particles penetrating into the central plasma regions increases by one and a half or two times, as compared to the case of using 2-eV-energy of particles.