NCSX Memorandum

To: T. Brown, A. Brooks, H-M. Fan, B. Nelson, D. Williamson, M. Cole, P. Goranson, R. Hatcher, C. Neumeyer, L. Dudek, P. Heitzenroeder, R. Ramakrishnan, J. Chrzanowski, L. Dudek, A. Klink, H. Kugel

CC: J. Schmidt, H. Neilson, J. Lyon, S. Hirshman, M. Zarnstorff, A. Reiman. L. Berry, D. Strickler, R. Simmons

From: W. Reiersen

Date: 2/22/2001

Re: Minutes of 2/21 Engineering telecon

An engineering telecon was held on February 21. The purpose of the meeting was threefold:

1. Discuss progress in assessing diagnostic access

2. Discuss final preparations for PVR

3. Discuss plans and priorities for the balance of FY01

David Johnson joined us for the first part of the meeting to provide his assessment of diagnostic access. His assessment was that the number and sizes of ports being provided approximately matched the number and sizes of ports required. However, the all-important task of factoring in geometrical constraints is not planned until conceptual design. Dave pointed out that the radial plates and TF coils significantly limited access and requested that we investigate ways to provide diagnostic access through those planes. Mike Cole noted that the PFC support rings were aligned with the radial plates. Cutting through the radial plates with a radial port would cut through the PFC support rings, which provide the heating and cooling to the CFC panels. The spacing between support rings is limited by the available panel size (roughly 18” square?). Dave also indicated that it is desirable to have diagnostic access on the v=0.5 symmetry plane. This is not possible in the present design, which features a bolted assembly joint at this location. Nevertheless, we need to consider creative ways of improving diagnostic access in conceptual design.

Cole and Williamson reported that preparation of the PVR write-up was coming along, being perhaps 2/3 complete. Nelson is returning to work on Monday. The first draft will be sent to PPPL on Tuesday. Only a few modifications to the existing stellarator model are planned. These modifications were characterized as “clean up” activities and include:

1. Modifying the trim coil geometry to avoid gross interferences with the NB and VV.

2. Putting adequate openings in the first wall (including cuts in the PFC support rings) to accommodate tangential NBI.

3. Reducing the size of the cutouts in the PFCs for diagnostic access. (The cutouts presently are as big as the ports.)

The cost estimate is close to complete. The only change that we need to fold in is the additional cost of full PFC coverage. The partial coverage option with the CFC panels does not look viable. Reiersen will set up a telecon on Monday to discuss final WBS costs with ORNL and PPPL.

RF access was also discussed. The trim coils that straddle the midplane on the outboard side occupy the same real estate that we had previously used for HHFW launchers. Art Brooks is investigating if these trim coils (the ones straddling the midplane on the outboard side) could be eliminated, thereby allowing us to continue to use that space for the HHFW launchers. Mike Cole will determine if eliminating those coils will indeed provide the space needed for the HHFW launchers. If so, that will be what we show for meeting our RF access requirements.

In addition, Tom Brown has been working with Dick Majeski to assess the prospects for inboard launch of low frequency RF. It appears that the space that can be made available might be adequate for an inside RF launch. However, the details of how this would play with an expanded vacuum vessel, the trim coils, and the bolted assembly joint still need to be worked out. At the PVR, if this feature is discussed, it should be characterized as work in progress. It will not be featured in the reference engineering design.

Discussions then turned to the post-PVR period and what our priorities should be. We anticipate Title I funding in FY03. This means that we should have a CDR is the spring of ’02 (probably tied to the budget cycle). For the CDR, we need to have manufacturing studies completed that give us demonstrable confidence that the coils and vacuum vessel can indeed be fabricated. The manufacturing studies should be initiated in the fall of ’01. By the time the manufacturing studies are initiated, we should already have made the big changes that we need to make in the modular coil design – how many coils (18 or 21); where are they located with respect to the symmetry planes; can we improve the smoothness of the surface they are located on (really the surface the shell is located on); can we increase the space provided for the first wall, trim coils, vacuum vessel (with cooling tubes and insulation), and assembly gaps; are the coils still double-valued or can this feature be eliminated with supplemental coils; can we eliminate twist from the winding to facilitate machining; etc. There is a tremendous amount of work to be done. This is very labor intensive work and needs to be initiated ASAP. Manufacturing studies are also needed for the vacuum vessel. We need to start lining up potential vendors prior to the fall and should consider international options such as Ansaldo and Japanese and Korean sources. The most urgent thing is getting Strickler and Berry working on exploring these potential improvements with CoilOpt. Engineering needs to coordinate with Physics to ensure that our plans are well-matched.