Speakers
Description
Collisions between charged and neutral particles in plasma can lead to energy and momentum transfer, which can affect plasma temperature and density profiles. Understanding and controlling these transport properties is necessary to achieve and maintain the conditions required for nuclear fusion reactions to occur in a tokamak.
In this study, we investigate collision frequency and energy transfer between electrons and Helium atoms. The interaction between an incoming electron and He atom was studied by the optical potential method, which consists of three interaction potentials accounting for various effects. Momentum-transfer cross section and phase shifts are found using the partial wave expansion and the variable phase approach, respectively.
The resulting effective frequency has a maximum depending on the energy. The experimental data found in the literature are consistent with the detected maximum. At energies lower than the maximum energy, our results coincide with other works. Energy transfer calculations for the energy values above the detected maximum showed that temperature equalization between helium and electron occurs more slowly than has been known.
Large tokamaks, including JET and JT-60U, also produce electron-positron pairs in plasma, where collisions between several MeV runaway electrons and thermal particles can produce up to 1014 positrons. How many positrons are generated depending on the energy of the runaway electrons, the differential production rate can be calculated using the runaway electron distribution and the Coulomb logarithm.
This research has been funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP AP19679536)
