NCSX Memorandum

To: Distribution

From: Wayne Reiersen

Date: 12/6/2000

Re: Revised PF system for 1017 modular coil design

Mike Zarnstorff provided PF coil currents for our 2T reference scenario for the S1, S2, and S3 states. I took these coil locations and currents and proceeded to “regularize” the PF currents, adjust the number of turns and locations of coil centers, and make the volt-second accounting come out OK. In the process, it was noted that PF3 and PF5 serve no real purpose. PF3 and PF5 were subsequently removed from the PF design. The table below shows the new and old coil geometry.

Coil areas were increased to reduce current density and coil stresses. Also, in the new coil design, a standard conductor (2.5cm x 2.5cm) was used throughout. The locations of the coil centroids are shown in the figure below.

Using this reduced set of PF coils, we were still able to provide a reasonably good fit to the fields generated by the PF coils used by Zarnstorff and reduce the maximum currents significantly. The most difficult fit was the vacuum case, S1, shown below.

Current requirements for the full current, zero beta case, S2, were comparable to S1.

Since the modular coil set (1017) was generated for the full current, high beta condition, S3, in the absence of PF coils, it is not surprising that the coil currents for S3 were the most benign of all.

This simple set of 5 PF coils is still able to provide a reasonably high quality field null, with the stray field in the plasma region being less than 1.5 gauss over the region from 1.2m to 2.1m with a 1 Wb flux linkage.

Power supply requirements for this scenario are formidable. A tabulation of coil currents and power supply requirements is shown below is shown below. 38 TFTR power supply sections appear to be required. PF1 is the biggest hog, requiring 10 power supply sections because it is double swung.

Engineering should use these currents as the basis for analysis of the reference modular coil design (aka 1017). Follow up actions include:

· Assess impact of vertical field only for S1 (Reiersen, Zarnstorff)

· Update “coils” file (Brooks)

· Provide updated inductance matrix (Brooks)

· Verify that the new coil positions are okay (Williamson)

· Check PF stresses due to PF coil currents (Nelson)

· Check electrical calculations with LRSIM (Hatcher, Neumeyer)

· Update the technical data sheet for the 1017 coil set (Reiersen)

· Generate current waveforms for the 1T reference scenario (Reiersen)