Task IS ummary of 12 7 99 by 4bnW938

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									          Summary of the 1st Teleconference Call held on December 7, 1999
    APEX Task I: Explore options and issues for implementing a flowing liquid wall in
                         a major experimental physics device

A. Attendance

Task Performers Present:                           Task Performers Absent:

Alice Ying, UCLA                                   Richard Nygren, SNL (time conflict for
Mike Ulrickson, SNL                                PFC review?)
Bob Kaita, PPPL                                    Ahmed Hassanein, ANL
Bob Woolley, PPPL                                  Kathy McCarthy, INEEL
Brad Nelson, ORNL                                  Neil Morley, Sergey Smolentsev, UCLA
                                                   (time conflict)
APEX Members Present:
Mahmoud Youssef (who helped take
notes)

B. Agenda/Lead discussion responsible person

(1) Review of Subtask Description (all),
(2) Update on the (technology and physics) objectives of the flowing liquid wall tests
    (Ying/Kaita/ALL),
(3) Initial input to issues concerning flowing liquid wall tests (Ulrickson/all),
(4) Progress on configurations and liquid wall options (Nelson),
(5) Plan on LM experimental facility design (Woolley/Morley),
(6) Plan on hydrodynamics and heat transfer analysis (Smolentsev),
(7) Initial input to the R&D plan (all)
(8) Problems/Other business

C. Brief Summary of the Agenda Items

1. Review of Subtask Description

-     Most task performers agree with their subtasks as written in the Task I Plan.
      Ulrickson may have some changes to make after the PFC review (Thursday).

2. Update on the (technology and physics) objectives of the flowing liquid wall
   tests, and
3. Initial input to issues concerning flowing liquid wall tests

-     Several SC members have expressed their views on the objectives of the flowing
      liquid wall tests. The objectives of the task should be completed as directed by the SC
      members. Yet, we should limit the list of the objectives to one page (Abdou). Abdou




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    will gather consensus on the objectives of the flowing liquid wall tests and issue a
    letter to Lab directors.

-   None of the experimental physics devices have a dedicated mission for flowing liquid
    wall tests. We still need a rationale for doing the liquid wall experiment on NSTX (or
    others) that contributes to its program, since it is not a device that has plasma-surface
    interactions as a main focus (Kaita).

-   We would still need to examine if the limited lithium coverage and whatever
    reduction in recycling we expect to have in the presence of large carbon surfaces that
    remain exposed will impact NSTX performance enough to be worth the effort. Note
    that there are already established techniques for depositing lithium coatings on the
    surfaces of large magnetic fusion devices, so the clear advantages of proposed liquid
    lithium schemes over them need to be demonstrated as well (Kaita).

-   Deployment of LM in large machines should be within the mission of their programs
    (Kaita, Ulrickson). This deployment may require major changes to the facility such as
    special diagnostics, ES&H, window coating, etc. (Ulrickson). To study the effects of
    liquid/plasma interactions on plasma will require new diagnostics. In addition, we
    may need to establish a “baseline” case for comparison as a “shaped” solid lithium
    piece used in the CDX-U experiments (Ulrickson).

-   I'm not sure that we can treat liquid metals as a proven technique (tool) for heat
    removal that is equivalent or better, for example, than the carbon tiles we are using
    quite effectively and economically on NSTX, and so far, no plan to use LM there in
    the future (Kaita).

-   ALPS effort on LM divertor and APEX effort on LM FW should be understood
    (Kaita). Integration of the two efforts is part of APEX tasks (Ulrickson, Ying
    Youssef). Nygren is undertaking this task.

-   How much LM inventory is allowed in each machine should be assessed (Ying). This
    inventory depends on the objectives of LM deployment in the machine (to provide
    improvement of plasma performance or LM is used in a dedicated area). The latter
    may require coating not just the limiter region but most parts of the machine (Kaita)

-   Hydrogen pumping becomes an important design variation if LM is deployed with
    large quantities (Ulrickson).

-   How to make flowing LM wall works in a machine requires a substantial R&D effort
    (Nelson). The goal is to make such a flowing liquid wall as a tool that can be applied
    in a major experimental physics device (Ying).

-   Getting liquid in and out with a large quantity is an issue (Ulrickson). Safety issues
    are a concern (Nelson). If liquid is going to be routed in pipes we need a diagnostic


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    system to detect leaks. Having a well controled situation such as a static pool is easy
    to handle but not when LM starts to flow. ES&H becomes a matter that requires
    “step function” increases in effort in going from finite static volume to flowing
    liquids (Kaita, Ulrickson).

-   MHD issue could be studied off-line and before hand (not in the facility). Other issues
    (e.g. erosion) could also be studied off-line. We need to develop a list of tests that
    could be done off-line (Wooley, Ulrickson, Ying).

4. Progress on Configurations and liquid wall options for NSTX

-   NSTX CAD model was retrieved and tested (Nelson). Nelson sent photographs of the
    divertor plate, bottom part of portion of the NSTX, and heat load to the Group just
    prior to the meeting. Unfortunately, due to various circumstances none of the
    conference participants had a chance to review it. All will look and comment on these
    CAD Drawings that were provided by Nelson. However, there is a need to revise the
    heat load profiles.

-   At this juncture, it is important to keep several flowing liquid wall design options: a
    design over lower divertor, a partial liquid wall that covers the passive plates and
    divertor in the lower half of NSTX, and a complex scheme of flowing down on the
    center stack (Kaita). Also direction of flow in the divertor would depend on the
    entrainment level. However, the direction of the flow is not an issue at present
    (Ulrickson).

-   We should not limit our thinking to only NSTX machine but to others (Ulrickson).
    However, just for starters and since it is premature to get into the details, we should
    take NSTX as a reference and begin to examine some generic issues (Kaita, Ying).
    We have no intention to exclude other machines.

5. Plan on LM experimental facility design

-   Design options and very approximate calculations for some possible laboratory
    experimental Liquid Metal Magnetohydrodynamic (LMMHD) toroidal facility
    configurations using up-to 24 coils that are available at UCLA were explored and
    performed by Bob Woolley. Within the extended capability of RapidPower
    Technologies Inc power supply to be sent from Princeton, a torus having a major
    radius of ~78 cm constructed from 24 coils could reach a nominal field of ~ 0.3 tesla
    (Woolley). A design based on 16 coils may be desired due to less power requirements.
    (Ying for Morley). Continued discussion of this will be conducted through mini-
    conference calls.
-   The status of the power supply on a loan agreement between PPPL and UCLA was
    reported. Paper work to send a power supply on a loan agreement to UCLA is being
    processed.




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6. Plan on hydrodynamics and heat transfer analysis

-   Parameter characteristics of the magnetic field of NSTX have been requested from
    Kaita by Sergey (UCLA). e-mail was not received and the request will be sent again.
-   The modeling and analysis of spatial and temporal field effects on LM hydrodynamics
    will be conducted in 4 phases.

7. Initial input to the R&D plan

-   There are facilities available at ORNL that can be utilized for testing and
    experimentation within the APEX effort (Nelson). They are the mirror machine RFT
    facility (steady state field of 1-2 tesla, a plasma volume of about 1 m in dameter and
    length), and a Large Coil Test Facility which consists of a 35 foot diameter vacuum
    tank with two large superconducting coils. It should be possible to arrange the coils
    to provide 20 feet or more of vertical height through a 2+Tesla field.
-   We should develop a matrix of required facilities and issues to be addressed and
    decide on the best approach to address the issues with the existing facilities (Ying).

8. Problems/Other business

-   Travel by PPPL is limited and should be considered in future travel plans of PPPL
    personnel (Kaita).
-   We should down load software “NetMeeting” from the Microsoft web site, which
    could allow viewing graphs, etc. by others through the Internet for future calls
    (Nelson).

D. Action Items

No specific action items were mentioned during the meeting. The Task Performers were
asked to review Brad’s VGs. Mini-conference calls concerning the toroidal magnetic field
laboratory experiments will be conducted between UCLA and PPPL. In addition, the
Task Performers are to continue conducting the subtasks as already agreed in the Task I
Plan.

E. Next conference call is January 4, 2000 Tuesday at 12:00 p.m. PST. The number
   to dial in is (310) 794 5378.




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