Fusion Science and Technology / Volume 59 / Number 1T / January 2011 / Pages 199-201
Numerical kinetic model of axial confinement is developed. Simulations show that in semi-collisional regime axial losses are determined by narrow “beam” of cold ions. Analytical treatment is proposed for the case of square-well magnetic field. Simulation of the ambipolar trapping of axial losses in the intermediate collision frequency range shows that essential suppression of axial losses is possible even when ambipolar barrier is of the order of ion temperature.