May 23, 2001

Presentations

Minutes

A meeting was held on May 23.  The purpose of the meeting was to status current tasks.

Dave Williamson discussed progress in the implementation of engineering constraints and metrics in CoilOpt.  CoilOpt has recently been modified by Dennis Strickler to incorporate a feature for multi-filament representation of the winding pack.  This capability should result in an improved estimate of the fit (Bavg, Bmax) and also engineering metrics such as current density, twist, and radii of curvature.  A test case with 18 modular coils (none on the symmetry planes) was shown.  Williamson then discussed smoothing of the winding surface.

Substantial progress has been made in adding features to CoilOpt.  However, we are not as far along as we had hoped.  Strickler has also been working on marrying of CoilOpt and StellOpt.  We need to adjust our plans to reflect Strickler's other commitments.  Strickler agreed to  provide his best estimate of when CoilOpt will be ready to run with the engineering metrics and constraints incorporated, and when the combined CoilOpt-StellOpt code development might be complete.

So far, Strickler has been working with the 1.7m li383 plasma configuration.  A table of completed runs was provided.  (See CoilOpt Runs link at top of page.)  Brooks indicated that all of the data files necessary to work at the reference size (1.4m) are available on the Web.  Strickler agreed to begin doing his calculations at the reference size.

One of the constraints is the plasma-to-coil distance.  As discussed the previous week, the real constraints are complicated by a non-uniform SOL thickness and the envelope requirements for a pumped divertor and RF launcher.  Mike Cole is working with Dick Majeski to establish the envelope requirements for the RF launcher.  Brad Nelson agreed to work with Peter Mioduszewski to lay out an envelope for a pumped divertor.

We then discussed conductor R&D.  Nelson would like to purchase conductor for characterization of orthotropic properties and other uses.  Heitzenroeder indicated prior to the meeting that General Atomics (Thome) had recently used a very nice, flexible conductor in the construction of a homopolar generator.  Heitzenroeder was awaiting the name of the vendor and will forward it to Nelson upon receipt.

Art Brooks reported on recent work calculating disruption loads on the vacuum vessel.  At the previous meeting, Brooks reported on stresses due to vacuum loads (22ksi max) and disruption loads at 1.7T with a 175kA plasma (26ksi max).  Brooks subsequently ran a combined loading case.  Maximum stresses went up to 37ksi.  Increasing the TF field to 2T by adding a 0.3T background 1/R field actually lowered stresses by a very small amount.  Brooks cautioned that these calculations did not include any toroidal flux changes in the plasma that would drive poloidal currents that would interact with the toroidal field.  Brooks ran a case with a plasma current of 350kA.  He noted that he did not change the background coil currents so it is not truly a representative case.  [Reiersen agreed to contact Zarnstorff for coil currents for a high plasma current case.] The maximum stress in the high current case was 67ksi.  Brooks calculations were based on a shell thickness of 0.25".  Because of the size of the model, a coarse mesh of the 360° vacuum vessel had to be used.  It was agreed that the thickness in the analysis should be increased to the nominal thickness of 0.375".  This is about the maximum thickness that can be accommodated while still meeting the 10ms time constant requirement.  Brooks will repeat the calculations with the thicker vacuum vessel and provide a recommendation on the maximum plasma current that can be accommodated.  Dahlgren agreed to review the material selection and provide a recommendation.  (The reference material is Inconel 625.)

Neilson mentioned that our responses to the PVR recommendations have been posted on the Web.  (Click here to get the the PVR page.)  Our plans have to be changed, if necessary, to include these activities.  Reiersen will update the plans accordingly.  Physics tasks are proceeding on a schedule that is at odds with the deliverable dates implied in the Engineering plans. Reiersen will discuss with Zarnstorff deliverables required from Physics and update the Engineering plans accordingly.

The acquisition strategy document has been reviewed internally.  Reiersen will incorporate recommended changes and send it back to the reviewers.  A meeting will be set up with Templon (PPPL Procurement) and Winkler (PPPL Business Operations) to discuss the proposed strategy.

The next meeting will be next week, Wednesday May 30, at the regular time, 1:30EDT.  We will again be using the PPPL bridge (x2822) with the same access code (6789).

Please forward any comments to reiersen@pppl.gov

(last edited on 09/25/2001 03:47 PM )