Evidence of lasing on the Balmer-α line of OVIII in an ablative capillary discharge.

In a low-inductance ablative discharge through a capillary made of polyacetal (POM), lasing on the Balmer-α line of OVIII at 10.24 nm is identified. In line with previous studies of lasing on CVI ions, it is argued to be the consequence of charge exchange collisions after a m=0 instability.

Calculation of low-Z impurity pellet induced fluxes of charge exchange neutral particles escaping from magnetically confined toroidal plasmas.

Measurements of energy- and time-resolved neutral hydrogen and helium fluxes from an impurity pellet ablation cloud, referred to as pellet charge exchange or PCX experiments, can be used to study local fast ion energy distributions in fusion plasmas. The estimation of the local distribution function f(i)(E) of fast ions entering the cloud requires knowledge of both the fraction F(0)(E) of incident ions exiting the cloud as neutral atoms and the attenuation factor A(E,rho) describing the loss of fast atoms in the plasma. Determination of A(E,rho), in turn, requires the total stopping cross section sigma(loss) of neutral atoms in the plasma and the Jacobian reflecting the measurement geometry and the magnetic surface shape.