From: Arthur W. Brooks
Sent: Tuesday, October 23, 2007 4:35 PM
To: Michael C. Zarnstorff; Hutch Neilson; Phil Heitzenroeder
Cc: Thomas G. Brown; Michael R. Kalish
Subject: RE: FYI - Update on Trim Coil Performance

Attachments: Assembly Field Errors with 36-24 Trim Coil Correction Study
r1.xls

Folks,

I've folded in HM's latest results for Modular Coil deflections (EM + Gravity). While the gravity deflections are lower (~0.3 mm max) the EM deflections are higher (~2.9 mm) than the case previously analyzed for field errors. As a result, we can still show adequate margin at the 95% level but not at the 100% level unless we justify excluding wing weld distortions.

Art

-----Original Message-----
From: Arthur W. Brooks 
Sent: Monday, October 22, 2007 10:01 AM
To: Michael C. Zarnstorff
Cc: Thomas G. Brown; Michael R. Kalish; Hutch Neilson; Phil Heitzenroeder
Subject: FYI - Update on Trim Coil Performance

Mike,

Just and update on the Trim Coil Performance - 

Tom has generated ProE models of the Reference Trim Coil Configuration (24 coils circuits with coils straddling symmetry planes split in two for assembly giving 36 total coils, 4 coil types ). The coils are necessarily larger (in extent, not cross-section) to avoid interfaces, particular the outboard coils which have ~33% larger area when compared to thee initial 72 coil groupings. This is good news in that it  has translated in to lower trim coils currents or the ability do more within the 20 KAT limit.

The attached spreadsheet summaries the performance achieved with these coils. I have included the calculation for the maximum of 100% of the random ensemble as well as the 95% level previously quoted. For the 100% cases, the trim coil currents are limited to 20 KAT and the residual islands grow to just over 10%.

I've added data for most of what we know from other significant field error sources - Modular Leads, EM deflections, Building Steel with PF6 correction, Residual Modular Coil Field Errors after realignment and the potential 1mm Wing Distortion from Welding. 

The Weld distortion can be a significant component and if we can justify leaving it out the bottom line looks much better.

Art