Asymmetry of dense divertor plasmas influenced by thermoelectric potential and charge-exchange momentum loss

Asymmetric equilibria of divertor plasmas influenced by the thermoelectric potential and the momentum loss due to the charge-exchange collisions have been studied by using a five-point model. The momentum loss becomes large when the divertor plasma temperature decreases below about 10 eV. The increase of the pre-sheath potential due to the momentum loss compensates the reduction of the sheath potential at the low-temperature side of an asymmetric equilibrium. Through the change of the pre-sheath potential, the momentum loss has a stabilizing effect on the thermoelectric instability and mitigates the asymmetry at the high-density divertor regime. The momentum loss at the low-temperature and high-density side divertor is effective to lower the temperature at the high-temperature side divertor.