Performance Projections for the Lithium Tokamak eXperiment (LTX)

Use of a large-area liquid lithium limiter in the CDX-U tokamak produced the largest relative increase (an enhancement factor of 5-10) in Ohmic tokamak confinement ever observed. Numerical simulations of CDX-U low recycling discharges have now been performed with the ASTRA code, utilizing a model with neoclassical ion transport and boundary conditions suitable to a nonrecycling wall, with fueling via edge gas puffing. This transport model has successfully reproduced the experimental values of the energy confinement (5 – 6 msec), loop voltage (<0.5V), and density for a typical CDX-U lithium discharge. In addition, DEGAS 2 modeling has now been performed for low recycling CDX-U discharges. The transport model benchmarked with CDX-U data has also been used to project the performance of the new Lithium Tokamak eXperiment (LTX), in Ohmic operation, or with modest neutral beam injection (NBI). NBI in LTX, with a low recycling wall of liquid lithium, is predicted to result in core electron and ion temperatures of 1 – 2 keV, and energy confinement times in excess of 50 msec.