Non-statistical simulations for neutral beam spectroscopy in fusion plasmas

While most of the existing models for calculation of neutral beam emission and attenuation in a fusion plasma assume a statistical distribution of population for the excited states of the beam, the observed motional Stark effect data reveal significant deviations from the statistical predictions. To address this problem, we developed a new collisional-radiative model based on the parabolic states which are the true eigenstates of a hydrogen atom in an induced electric field. This model is completely resolved in the magnetic quantum numbers up to n=10 without any assumption of a statistical distribution. Calculation of collisional cross sections between the parabolic states is based on the atomic-orbital close coupling and Glauber approximations for density matrix elements. Our simulations show excellent agreement with the experimental data from the JET tokamak and also can be used to define the limits for the application of statistical approximation.