NCSX Memorandum

To: Distribution

From: Wayne Reiersen

Date: 12/12/2000

Re: More revisions to the PF system for 1017 modular coil design

Yesterday, I issued a memo describing a new PF system design for the 1017 modular coil case. The purpose of this memo is to identify two subsequent changes and their impact on the current waveforms. These changes were:

1. An improved OH distribution was identified, reducing the maximum stray field from 1.5 gauss to 0.6 gauss in the region from 1.25 to 2.2m.

2. The number of turns in the two OH coils (PF1 and PF2) in the vertical direction was increased from 16 to 20. The winding pack height and current centroid locations were not changed. A slightly squatter conductor would have to be used for these two coils.

The number of TFTR power supply sections required would be reduced slightly from 38 to 37. The maximum conductor current would drop from 33kA to 23kA. (One caveat is that the power supply calculations are being done with the old inductance matrix, which has not been updated to reflect the new coil centroid locations. They will be repeated as soon as a new inductance matrix is generated.)

A sensitivity study was performed to determine the impact on the number of power supply sections required and maximum conductor current if the PF coils were only required to provide a vertical field for the vacuum state, S1. The results indicated that the number of power could be reduced by 8 (from 37 to 29) and that the maximum conductor current could be reduced from 23kA to 18kA simply by changing the PF requirements for S1.

PF coil currents for the S1, S2, and S3 states and their fit to the prescribed fields are shown in the sequence of tables below.

The vertical field on the horizontal midplane arising from the 1Vs OH distribution is as shown below.