The conversion of the thermal energy of plasma in the SOL of tokamaks

Abstract

When the plasma expands across the confining magnetic field, a part of its thermal energy is converted to electrical energy. In the SOL of tokamaks, the motion of the plasma across the field due to turbulent processes is accompanied by its departure along the open lines of the magnetic field. The conversion of thermal energy is taken into account in theoretical studies devoted to the physics of plasma in the SOL; however, this conversion is ignored in numerical models, for example, in B2–SOLPS4.0. This paper deals with thermal-to-electrical energy conversion in the SOL of tokamaks. It is demonstrated that the part of the thermal energy subjected to conversion to electrical energy forms an appreciable part of the total energy flowing in the SOL. In ITER, this fraction may be as high as 20–25%. The electrical energy generated in the SOL volume is liberated in the form of Joule heat in a relatively cold plasma in the vicinity of diverter plates or directly on these plates.

Influence of scrape-off layer on plasma confinement

“…10 As plasma flows along field lines in the SOL toward the divertor the field lines expand and part of the plasma thermal energy is converted into electrical energy, which can produce significant ohmic heating of the divertor plasma or target plate. 11 It is becoming feasible to measure the neutral density distribution and ionization source term in the edge plasma by spectroscopy. For example, computer modeling of neutral density distributions by the EIRENE code has been validated by spectroscopic measurements in the edge plasma of the TJ-II stellarator.…”

Polarization currents in tokamak scrape-off layer at disruptions and edge-localized modes

“…The relation γ /ω B depends on the transfer of energy from the plasma core to the SOL, which is not studied sufficiently. If the thermoconductivity and diffusion turbulent coefficients are similar to such coefficients in stationary regimes one can make the following assessment: the turbulent coefficient of thermoconductivity χ ⊥ is several times higher than the diffusion one D ⊥ , the heat fluxes due to thermal conductivity and convection are comparable in magnitude [6], γ ≈ χ /λ 2 T . If we assume that the total effective coefficient of thermoconductivity χ ≈ D ⊥ , in that case…”