AWB Dimensional Control Requirements for the Modular Coils and TF coils Field Period Assembly Peer Review October 11-12, 2006 Art Brooks

AWB Overview Physics Requirements on Installed Coil Current Centers Coil Tolerances Tolerance Breakdown between Stations Modular Coil Winding Form Measurement Data and As- Wound Coil Current Centers Achieved Improvements thru Coil Realignment

AWB Physics Requirements from GRD relates to Field Errors: –Field error correction (trim) coils shall be provided to compensate for fabrication errors. –The toroidal flux in island regions due to fabrication errors, magnetic materials, and eddy currents shall not exceed 10% of the total toroidal flux in the plasma (including compensation) Tolerance set based partially on experience of other machines –1 part in 1000 or 1.5 mm for a 1.5 m device Extensive tolerance studies done to verify that field errors from coils in conjunction with trim coils can achieve desired field quality –see “Field Errors and Coil Tolerances, NCSX FDR, May 19-20, 2004” Tolerances on coils with less impact on field errors (further from the plasma) were softened Requirements

AWB Coil Tolerances Specifications The Coil Tolerance herein pertains to the location of the current center of the installed coils relative to the ideal/theoretical position: –Modular Coils +/- 1.5 mm (0.060 in) –PF Coils+/- 3.0 mm (0.120 in) –TF Coils+/- 3.0 mm (0.120 in) –Trim Coils+/- 3.0 mm (0.120 in) Tolerances are further allocated to limit tolerance buildup between various fabrication and assembly operations.

AWB Modular Coils Tolerance Allocation Vendor Machining of MCWF (+/ )” In House Coil Winding Process +/ ” –(Includes prior machining) –Realignment offers chance for improvements Half Period (3 Pack) Assembly +/ ” –Flange to Flange Alignment (B-A, C-B) Full Period Assembly over VV +/ ” –Flange to Flange Alignment (A-A) 3 Period Assembly in Test Cell +/ ” –Flange to Flange Alignment (Cs-Cs)

AWB Correcting MCWF Out of Tolerances During Modular Coil Winding Machining of MCWF Base and Septum winding surfaces were out of tolerance ~0.050” in some locations Adjustments to Coil Winding Pack led to meeting current center requirements over most of the coils AB Base Septum

AWB Modular Coil Type C Clamp Number Convention and Side A/B Designation

AWB Summary of As-Built Dimensions on MCWF Type C Coils – Side A Septum

AWB Summary of As-Built Dimensions on MCWF Type C Coils – Side B Septum

AWB Summary of As-Built Dimensions on MCWF Type C Coils– Side A Base

AWB Summary of As-Built Dimensions on MCWF Type C Coils– Side B Base

AWB C1 C2 C3 C4 C5

AWB Maintaining Coil Current Centers After Winding Winding process allows for controlling current center by adjusting Coil Winding Clamps Emphasis was placed on making all coils alike by winding coils to match current center achieved on prior coils: –C1 targeted design, C2 targeted C1, C3 targeted average of C1 and C2,... Nominal coil geometry will be redefined based on average current center achieved for each coil type.

AWB Modular Coils Type C Current Centers After Winding Relative to Targets Note - This is only a measure of how well coils were wound

AWB Modular Coils Type C Current Centers After Winding Relative to Targets Note - This is only a measure of how well coils were wound

AWB Final Modular Coils Type C Current Centers After Winding Relative to Design Targeting of prior coils has lead to uniform coils

AWB Final Modular Coils Type C Current Centers After Winding Relative to Design Targeting of prior coils has lead to uniform coils

AWB Average of C Coils to date

AWB Average of C Coils to date

AWB Further Corrections with Coil Realignment Knowing the as-built coil geometry permits analytic determination of would-be field errors. By making small adjustments to the reference positions of each coil, the dominant resonant field errors can be suppressed. Coil realignments can be calculated independently for each coil using the 6 dof, or collectively within a coil type allowing for targeting of more modes with potentially lower displacements.

AWB Independent Realignment

AWB Collective Realignment

AWB Summary Tolerances are tight but necessary, in conjunction with trim coils, to maintain field quality Coil Winding Process has been able to correct some of the OOT from the machining of the MCWF Coil Realignment should allow for further corrections as needed to reduce resonant field errors