Time Dependent Model For D-/sup 3/ He Fusion Ignition and Burning in a Tokamak

A numerical, time dependent model for studying the major physical processes involved in D-
³
He and D-D ignition and burning has been implemented in the BALDUR transport code. A version is publicly available. The model follows the evolution of the thermal ion species
¹
H,
²
H,
³
H,
³
He,
⁴
He, and an optional impurity. The fusion reactions that play a major role in the energy balance and the energetic neutron production, D+T, D+D, D+
³
He, and T+T, are included, with simple models for the collisional slowing down of the fast particles, first orbit losses, "ash" removal after slowing down, and fast ion-thermal ion fusion reactions. The high temperature synchrotron radiation model (S. Tamor) has been modified to remove instabilities due to the method of approximating the size of the central, optically thick region. The model allows the study of important aspects of D-
³
He and D-D ignition and burning, such as the effects of particle fuelling and recycling, ash removal, and the effects of finite plasma beta on both the plasma geometry and stability. Benchmarks and comparisons with a previously developed one dimensional transport code are presented. New results on the ignition and burning of D-
³
He with a D-T assisted start are presented, for a high magnetic field, tight aspect ratio tokamak.