From: Arthur W. Brooks
Sent: Thursday, February 28, 2008 11:29 AM
To: Sorin Homescu; Thomas G. Brown
Cc: Mike Cole; Michael C. Zarnstorff; 'Paul L Goranson'; Phil
Heitzenroeder
Subject: RE: Field Errors from Modular Coil Lead Configuration

Attachments: Modular Leads Field Errors AB only r1.xls


Folks,

I've looked at the latest lead design in the attached. More importantly, I found an error in my initial calculations which significantly overstated the problem (I was using total amp-turns in the coil instead of lead current - a factor of 22 on field errors). As a result, the initial designs were recomputed as well and found to be a lot less scary. 

The latest design with the cables running directly onto the coil lead blocks is still preferred since field errors are even lower. Resonant field errors small, producing islands in the plasma totaling ~2% and total (ie including non-resonant) normal field of less than 0.5 Gauss at the plasma boundary.

Art

-----Original Message-----
From: Sorin Homescu [mailto:homescus@alexmail.com] 
Sent: Monday, February 25, 2008 3:09 PM
To: Arthur W. Brooks
Cc: Mike Cole; Michael C. Zarnstorff; Thomas G. Brown; 'Paul L Goranson'
Subject: RE: Field Errors from Modular Coil Lead Configuration


Hello Art,

I have changed the design to the cables directly onto the coil lead blocks,
reduced as much as possible the space between the lead blocks as well as the
space between the cables before they all join in the circular pattern. 

I will continue with this concept, please provide feedback if any changes
are needed to further reduce the field errors. As soon as I have the next
IGES model (B) I will send it to you.

Regards,

Sorin

-----Original Message-----
From: Michael Zarnstorff [mailto:zarnstor@pppl.gov] 
Sent: Wednesday, February 13, 2008 9:35 AM
To: Arthur W. Brooks; Thomas G. Brown
Cc: Mike Cole; Sorin Homescu
Subject: Re: Field Errors from Modular Coil Lead Configuration

Yikes.

Why aren't the cables going directly onto the coil lead blocks?  I would 
think that would minimize the loops and thus the field errors...?

Mike.


At 09:01 AM 2/13/2008, Arthur W. Brooks wrote:
>Tom,
>
>I've calculated the field errors from the Modular Coil Lead
>configuration for the Type A and Type B coils. The point models provided
>by Sorin were converted into equivalent circuit coil filament files and
>run thru the VACISLD code. The results are attached.
>
>Resonant field errors are large, producing islands in the plasma
>totaling more than 10% and total (ie including non-resonant) normal
>field of more than 20 Gauss at the plasma boundary.
>
>I believe we need to strongly consider a more coax or nested arrangement
>of the leads as we discussed to reduce these field errors.
>
>Art