The divertor dome is the plasma facing component (PFC) located between the two divertor channels. It closes the private flux region to enhance neutral containment in the divertor region. This component must withstand heat loads of 5 MW/m² during nominal operation and transient heat loads of 15 MW/m² for 1-2 sec. The reference design for the dome PFC includes a 10-mm-thick layer of W-brush armor bonded to a 30-mm-thick, formed copper plate with tapered hypervapotron cooling channels. The W-brush armor reduces thermal stresses during operation, which appears to be necessary for joint reliability. This plate is diffusion-bonded to a thick copper manifold structure that distributes coolant to the vapotron channels. The PFC is mechanically attached to a 316L(N)-IG stainless steel body so that this potentially vulnerable component can be removed and replaced without displacing other PFCs. The US is developing processes necessary to fabricate the stainless steel body, fabricate the hypervapotron coolant channels, bond the W armor to the copper PFC, and then join this PFC subassembly to the stainless steel dome body.

The PFC coolant manifold will be fabricated from a CuCrZr forging with internal cooling passages drilled into it. The hypervapotron channels will be machined into a separate CuCrZr plate that is bonded to the PFC body using low-temperature (below 550^oC) hot-isostatic-pressing (HIP) assisted diffusion bonding methods. The same process is used to bond the W-brush armor to the copper alloy (CuCrZr) dome PFC structure. The 316L(N)-IG dome body is currently being considered as a cast and HIP structure that is fabricated using techniques identical to those being developed to fabricate the large divertor cassette body. Joining of the copper dome PFC subassembly to the stainless steel dome body will be accomplished by expanding two hollow copper pins into lugs extending off the rear of the PFC at the mating surfaces.

This paper will describe the dome assembly design details and manufacturing process development associated with each of the sub-components comprising this assembly.

* Work supported by US DOE under Contract AC-3013 with Sandia National Laboratories.