FIRE Design: FY03 PFC Tasks

1. FIRE Design: FY03 PFC Tasks NSO PAC Meeting San Diego, February 27-28, 2003 Mike Ulrickson (FIRE Divertor Design Team) presented by Richard Nygren (new member, NSO PAC) Sandia National Laboratories Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company,for the United States Department of Energy under contract DE-AC04-94AL85000.

2. Introduction • Best guess for readiness for PVR is late August or early September 2003. • Continuing resolution in FY03 has constrained the initial schedule. • In the following slides: green textindicates completed tasks, blue textindicates tasks in progress, black text indicates planned tasks that can be done with the FY03 budget.

3. Plasma Equilibrium green (completed) • Define baseline plasma shape for 2.14 m. • Use TSC to compute vertical and radial disruption cases. • Define the range of , li, , and Paux that should be accommodated and provide magnetic data. black text (can be done with FY03 $$)

4. Edge modeling • Use UEDGE to reestablish edge plasma conditions with the proper fusion power and heating • Determine heat flux profiles • Determine boundaries for partial detachment blue(in progress) black text (can be done with FY03 $$) Note: for high density plasma in ARIES-RS/CLIFF for APEX, Rognlien found steady state solution for strongly radiating regions near X-point.

5. Disruption Forces • Rebuild OPERA model of vessel and PFCs including copper(input from design at Boeing) • Use TSC data as input to Opera to find eddy currents and forces • Use Opera to determine the effect of the copper shell on magnetic diagnostics • Run a vertical disruption case to compare to vertical disruption on 2.0 m machine and use results to scale radial disruption forces to 2.14 m

6. Design • Revise baseline divertor design (input to Opera) • Revise the divertor hardware to accommodate the new plasmas and check shape variations • Compute stresses in the revised design for both thermal and disruption loads (input from Opera) • Revise design as needed to accommodate stresses green (completed) black text (can be done with FY03 $$)

7. Heat flux testing • Investigate new concept for W rod attachment to improve reliability (PFC base program but input from FIRE design) • New design completed • Negotiating with vendor for production green (completed) black text (can be done with FY03 $$)

8. W-rod Armor • Mockups have survived high heat flux tests to 24MW/m2 and thermal cycling for 500 cycles*. • We recommend two design improvements. - Creep resistant Cu alloy as the rod bed. - Positive mechanical lock of rod to bed (grooved rod tip). Vendor bids have been received. *PW-8 rods reached 3300oC at 24MW/m2. Some erosion of rods occurred but no cracking or melting. PW-8 was then subjected to thermal fatigue cycles After 370 cycles (10s-ON:10s-OFF) at 20MW/m2, one rod began to melt. The affected area grew to 9 rods; we terminated testing at 500 cycles.

9. ELMs on FIRE ELMS are not a problem if no surface melting occurs. We must reduce the magnitude of ELMS. • Most of the 2% cases and a few 5% cases are acceptable. • Limit for 0.1ms ELM is ~0.3 MJ/m2(partially detached, 12 MW/m2) • Limit for 1.0ms ELM is ~1.0 MJ/m2(partially detached, 12 MW/m2) • Assumptions for ELM energy deposited on FIRE divertor plates. • Either (a) 2% or (b) 5% of stored energy is lost. • Footprint for deposition is either (a) same as normal operation or (b) up to three times larger • Duration of ELM is 0.1<tELM<1ms

10. ELMs Melting LIMIT Melting will not occur when the deposited energy density is less thanthe value at the intersection of (a) T-rise curve and (b) TLIMIT,normalHF. T-rise (1ms ELM) 5% (loss Estored) 6MW/m2 q”normal Energy Density >1.25MJ/m2 to avoid melting.

11. PFC Task Progress

12. Reporting • Provide data needed for Physics Validation Review • Revise divertor section of engineering report to include new design

13. Summary • A redesign of the PFC components can be completed in time for the PVR, but the effort must start immediately. • Funding is not adequate for iterating the divertor design. • We can only scale the design to the new size and analyze the forces • Local areas of excessive stress are likely to exist on the supports or vacuum vessel