Particle confinement in a reversed field pinch plasma

The particle confinement time of boron, tau B , is studied in the TPE-1RM20 reversed field pinch plasma by means of a laser ablation technique. The experimental conditions were as follows: pinch parameter, Theta , and plasma current, I p , are scanned, and tau B obtained from a zero dimensional approximation is compared with the energy confinement time, tau E . The results show that tau B increases almost linearly with tau E , and the implication of this is discussed in terms of energy loss channels. The increase of tau B with Theta supports the recently obtained improved confinement at high Theta . Laser ablation results are compared with the particle confinement time of deuterium, tau p , from the D alpha line spectrum measurement. It is shown that tau b approximately= tau p , which indicates a weak mass dependence in particle transport. Numerical simulation is also conducted and compared on a one dimensional basis with the experimentally obtained spatial distribution of the line emission intensity of the boron impurity injected by the laser ablation. The result shows reasonable agreement with experiment