TPX divertor design

The TPX tokamak incorporates a double null slot divertor that may be operated in a single or double null mode. Provisions are incorporated to provide for radiative divertor operation to reduce the peak heat flux to the divertor. Particle pumping is provided through vertical ports to control the plasma density. This paper describes the conceptual design of the TPX divertor. The divertor is designed for steady state thermal operation. TPX pulse lengths will be from 1000 sec to steady-state. The materials used for the divertor are mostly titanium for the structure and water manifolds, dispersion strengthened copper for the water cooling tubes, and carbon-carbon (C-C) composite for the plasma facing surfaces. Low activation materials are used where possible in order to preserve hands on maintenance during the first two years of operation. Analysis indicates that surface heat fluxes as high as 15 MW/m² will heat the C-C plasma facing surface to above 1000°C. This temperature results in an acceptable impurity release of the high conductivity C-C materials. The divertor sector (22.5° toroidally) has been designed into two modules which are the inner divertor module and the baffle/outer divertor module. This was done to allow for installation/removal of the divertor within the space limitations of the TPX plasma chamber. Water coolant lines, diagnostic instrumentation, and gas lines for radiative divertor gas feed are designed to be remotely connected/disconnected. Module to module alignment is critical to limit edge heating of the C-C surface and this alignment has been achieved by using mounting rings forming a common surface for aligning the modules. Disruption and halo current loads are significant and set the requirements for structural strength and attachment points