Session KP01 - Poster Session III.
POSTER session, Tuesday afternoon, March 23
Exhibit Hall, GWCC
Quasi-omnigenous (or drift orbit-optimized) stellarators have recently been designed at low field periods (N_fp = 3,4), low aspect ratio (A = 3 - 4), low bootstrap current fraction, and high ranges of rotational transform (i = 0.5 - 0.8). Continuing improvement of these devices is underway and is guided by accurate evaluation of their physics characteristics. For confinement studies, we use a Monte Carlo model (DELTA5D) which follows ensembles of guiding center trajectories through 5-dimensional phase space (\Psi,øminus,\zeta,v_\|/v, and energy). Different particle initializations appropriate to thermal plasma, ICRF heated tail ions, and alphas in reactors have been developed and diagnostics include: local diffusivities, global losses, bootstrap current (using low noise \deltaf weightings), and loss patterns of particles exiting the outer flux surface. Application of this model to QO devices has demonstrated that they can achieve good core transport (\tau_E^neo\approx 2-3 \times \tau_E^ISS95) and sufficient confinement of energetic tail populations for efficient heating. We will discuss the transport characteristics of a variety of QO configurations of current interest.