Summary of Task B Activities*

Transcription

1 Summary of Task B Activities* R. Kaita and R. Woolley Princeton Plasma Physics Laboratory APEX Electronic Meeting and 15 August 2002 *with contributions from M. Ulrickson, B. Nelson, A. Hassanein, FLIRE, PISCES, CDX-U, and NSTX

2 Outline Identification of key issues and development of an R&D plan for implementing liquid surface module (LSM) in NSTX Plans for addressing issues raised at NSTX 5-Year Plan Ideas Forum Upcoming NSTX meetings where LSM presentations should be made Experiments and modeling with liquid walls Proposal for effort to design and fabricate new magnet for FLIBE research under JUPITER-II program Conclusions

3 module (LSM) in NSTX Plans for addressing issues raised at NSTX 5- Year Plan Ideas Forum. Effectiveness for helium pumping should be studied. FLIRE experiment at the University of Illinois should help in this area. Layout of internal ramps with stainless steel bracket and inlet tubes in the upper vacuum chamber of FLIRE.

4 Objectives of FLIRE experiment include:* Determine the characteristic retention time and diffusivity of incident He particles in flowing liquid lithium at a constant surface temperature and constant ion beam influx. Measure the surface temperature dependence of particle retention time and diffusivity for both helium and hydrogen ion beam irradiation. Study the dependence of incident beam particle energy and liquid-metal flow velocity on characteristic retention time and diffusivity for both H and He ion beam bombardment. Develop a preliminary design for the study of the effect of various magnetic field configurations and induced currents in the free surface flowing liquid on the particle entrainment time of He and H/D particles. *Monthly Report - April 30, 2002 Free Surface Flowing Liquid-Plasma Interaction Facility NPL Associates Inc. Jean Paul Allain, Principal Investigator George H. Miley, President University of Illinois, Urbana-Champaign David N. Ruzic, Sub-contract Principal Investigator Martin Nieto, Graduate Research Student

5 Effect of ELM s on liquid surface module should be investigated. Plasma-surface interactions already studied with nonuniform lithium layer on toroidal CDX-U limiter. No deleterious effects to date on plasma performance. Fast Camera Looking here Stills of plasma-lithium interactions in Li I light at 6708 Å; 1000 fps, 1/5000 s shutter speed 0.219s 0.220s 0.221s

6 New toroidal limiter tray is being installed in CDX-U. Plan is to load with liquid lithium with new UCSD injector. Plasma-surface interactions with uniform liquid lithium layer in toroidal limiter tray scheduled for October s Filling sequence using liquid lithium injector in PISCES lab shows creation of uniform layer in mockup of CDX-U limiter tray section.

7 A. Hassanein made presentation entitled Effects of Plasma Disruptions on Liquid Surfaces on August 24, 2000 (APEX Meeting 20). Used HEIGHTS (High Energy Interaction with General Heterogeneous Target Systems) simulation code. Compared results with vapor shield, droplet shield, and splashing in models of lithium, beryllium, and carbon as divertor surfaces. Erosion thickness of divertor plate materials predicted to have clear dependence on effects included. Consequences of different erosion predictions on plasma performance have yet to be determined.

8 Plans for addressing issues raised at NSTX 5- Year Plan Ideas Forum. Requirements for major machine modifications an issue.» Tight space may eliminate possibility for midplane module.» Divertor module may be more practical. Issues for NSTX divertor LSM option:» Toroidally-local module may be easier to install but more sensitive to toroidal displacement of lithium.» Fully-toroidal module easier to simulate but may be harder to implement: partial coverage of outboard divertor may avoid obstructing penetrations.

9 Issues for NSTX divertor LSM option Design constraints:» Maintain capability for coaxial helicity injection by restricting liquid surface to outer divertor region.» Toroidally-local or fully-toroidal options must provide liquid surface area of about 1 m 2.» Flow velocity of 10 m/s may be difficult with magnetic pumping due to low NSTX fields.

10 Issues for NSTX divertor LSM option Implementation issues:» Specify mechanical requirements (liquid metal inlet and outlet, structural support, etc.).» As built information needed to avoid interference with existing and planned hardware in divertor region.

11 Concept presented by M. Ulrickson at NSTX 5-Year Plan Ideas Forum (courtesy of B. Nelson): Fully-toroidal LSM covering entire outboard divertor region (about 24 wide). 3.3 m 2 surface area of outboard divertor means only 1/3 coverage will satisfy 1 m 2 area requirement

12 Issues for NSTX divertor LSM option As built divertor region with tiles: Flux loops behind removed secondary passive stabilizer plate module Penetrations for diagnostics Secondary passive stabilizer plates Diagnostic sensors embedded beneath carbon tiles Outboard divertor Gap between outboard and inboard divertors must be maintained for coaxial helicity injection Gap between outboard divertor and secondary passive stabilizer plates

13 Issues for NSTX divertor LSM option As built divertor module (tiles removed):» Note sensor hardware extending beneath module. Penetrations for diagnostics Flux loop underneath divertor module Lower section of outer divertor may be available for fully-toroidal liquid surface

14 Upcoming NSTX meetings where LSM presentations should be made NSTX Research Planning Forum: 9/11-9/12 (at Princeton Plasma Physics Lab).» Decision on particle control planned for end of FY03.» Presentation should address steps to take during FY03 to support that decision point.» May not include proposals to run experiments on NSTX but should mention results from NSTX, CDX-U, LIMITS, MTOR, etc. that could support LSM design.

15 Upcoming NSTX meetings where LSM presentations should be made ST Community Workshop: 11/18-11/20 (at Princeton Plasma Physics Lab)» Present latest experimental and computational results from CDX-U, LIMITS, MTOR, etc. in support of LSM design.» Provides background information for 5- Year Plan Workshop to follow.» Materials to be given to issues coordinators (H. Kugel and R. Maingi) prior to 5-Year Plan Workshop on 11/21 and 11/22 (also at PPPL).» Only issues coordinators will be giving summary talks on drafts they are preparing for comment at 5-Year Plan Workshop.

16 Experiments and modeling with liquid walls Experiments and modeling with liquid walls Proposal for effort to design and fabricate new magnet for FLIBE research under JUPITER-II program» Objective is to study magnetic effects on heat transfer in a low electrical conductivity fluid flowing turbulently in a pipe in facility at UCLA.» Deliverable is design of magnet to simulate FLIBE in fusion reactor.» Design activity to begin in FY03.» First phase is for R. Woolley to devote one man-month to design magnet as per statement of work prepared in FY02.» Second phase is construction of magnet if cost and schedule is acceptable to all parties.

17 Conclusions Identification of key issues and development of an R&D plan for implementing liquid surface module (LSM) in NSTX Goal should be to settle on conceptual design by ST Workshop.» Start addressing interferences and other implementation details by that time.» Fully-toroidal option in particular requires major machine changes Experiments and modeling with liquid walls: JUPITER-II magnet Goal should be to have agreement on statement of work and confirmation of funding in place by start of FY03.