Double-null divertor configuration discharge and disruptive heat flux simulation using TSC on EAST

The tokamak simulation code （TSC） is employed to simulate the complete evolution of a disruptive discharge in the experimental advanced superconducting tokamak. The multiplication factor of the anomalous transport coefficient was adjusted to model the major disruptive discharge with double-null divertor configuration based on shot 61 916. The real-time feed-back control system for the plasma displacement was employed. Modeling results of the evolution of the poloidal field coil currents, the plasma current, the major radius, the plasma configuration all show agreement with experimental measurements. Results from the simulation show that during disruption, heat flux about 8 MW m-2 flows to the upper divertor target plate and about 6 MW m-2 flows to the lower divertor target plate. Computations predict that different amounts of heat fluxes on the divertor target plate could result by adjusting the multiplication factor of the anomalous transport coefficient. This shows that TSC has high flexibility and predictability.

Concise and efficient direct-view generation of arbitrary cylindrical vector beams by a vortex half-wave plate

A concise, efficient, and practical direct-view scheme is presented to generate arbitrary cylindrical vector(CV)beams, including CV beams, vortex beams, and cylindrical vector vortex(CVV) beams, by a vortex half-wave plate(VHP). Six kinds of first-order and other high-order CV beams, such as azimuthally polarized(AP) beams, antivortex radial polarization mode beams, and three-order AP beams, are formed by simply rotating a half-wave plate. The Stokes parameters and double-slit interference of multitype CV beams are investigated in detail.The polarization parameters, including degree of polarization, polarization azimuth, and ellipticity, are obtained,which demonstrates the efficient generation of CV beams. In addition, the double-slit interference experiment is introduced in the setup, and fringe misplacement and tilt appear for CVV beams, in which the misplacement number M is 2P+1 for P ≤ 2 and 2P-1 for P ≥ 3, where P is the polarization order number, and the fringe tilt offset is positively related to the topological charge number l of CVV beams. In addition, new types of VHPs can be formed by cascading two or more VHPs when the types of available VHPs are limited, assisting in more flexible generation of multitype CV beams. It is experimentally demonstrated that arbitrary CV beams with high quality are effectively achieved by the proposed setup, and the double-slit interference method can be utilized to determine and analyze CV beams rapidly and concisely by practical performance, which shows the potential to be implemented as a commercial device.