Parameter exploration for a Compact Advanced Tokamak DEMO*

A new parameter study has explored a range of design points to assess the physics feasibility for a compact 200MWe advanced tokamak DEMO that combines high beta ($\beta_N<4$) and high toroidal field ($B_T=6-7$T). A unique aspect of this study is the use of a FASTRAN modeling suite that combines integrated transport, pedestal, stability, and heating & current drive calculations to predict steady-state solutions with neutral beam and helicon powered current drive. This study has identified a range of design solutions in a compact ($R_0=4$m), high-field ($B_T=6-7$T), strongly-shaped ($\kappa=2$, $\delta=0.6$) device. Unlike previous proposals, C-AT DEMO takes advantage of high-beta operation as well as emerging advances in magnet technology to demonstrate net electric production in a moderately sized machine. We present results showing that the large bootstrap fraction and low recirculating power enabled by high normalized beta can achieve tolerable heat and neutron load with good H-mode access. The prediction of operating points with simultaneously achieved high-confinement ($H_{98}<1.3$), high-density ($f_{GW}<1.3$), and high-beta warrants additional assessment of this approach towards a cost-attractive DEMO device.