NCSX B. Nelson for the NCSX Engineering Team NCSX modular coil cooling workshop June 10-11, 2004 PPPL NCSX Modular Coil Cooling Requirements and Initial Design

NCSX June 10-11, 2004NCSX modular coil cooling workshopB. Nelson 2 Coil system requirements Meet Performance and flexibility requirements –Up to 2 T, 15 minute rep rate –Independent control of modular and PF coils Minimize magnetic field errors: Limit islands to < 10% of toroidal flux –Windings must have +/- 1.5 mm installed accuracy –Magnetic permeability < 1.02 –minimum perturbations from leads, crossovers, etc. Accommodate access for tangential NBI, RF, vacuum pumping, diagnostics and personnel access Ensure voltage and current requirements match D-site power supplies Coils must be buildable

NCSX June 10-11, 2004NCSX modular coil cooling workshopB. Nelson 3 Compact design requires careful space allocation structure winding vessel PFCs

NCSX June 10-11, 2004NCSX modular coil cooling workshopB. Nelson 4 Modular coils wound on “tee” structure Parameters: Coil Envelope = 2 x x in. Current / Coil = up to 831-kA-turns Number of Turns = 20 (A,B) and 18 (C) Max current / turn = kA Conductor Size =.351 x.391 in Cu Current Density = 15.1-kA/cm2 (max) Conductor operating temp. range 85K-125K Parameters: Coil Envelope = 2 x x in. Current / Coil = up to 831-kA-turns Number of Turns = 20 (A,B) and 18 (C) Max current / turn = kA Conductor Size =.351 x.391 in Cu Current Density = 15.1-kA/cm2 (max) Conductor operating temp. range 85K-125K After Compaction Before Compaction Flexible cable used to wind coil Cooling tube Groove for sealing VPI jacket Structural clamp assembly with belleville washers for compliance Copper chill plates Copper cladding

NCSX June 10-11, 2004NCSX modular coil cooling workshopB. Nelson 5 Modular coils cooled at winding surface Cu cladding Chill plates and cooling tube End of pulse + 3 min+ 7 min + 15 min Cooldown after pulse in 15 min ~130K ~ 85K

NCSX June 10-11, 2004NCSX modular coil cooling workshopB. Nelson 6 Baseline cooling concept requirements/constraints 15 minute cooldown between pulses Copper cladding and chill plates are electrically isolated from tee No electrical continuity (loops) in copper parts in any direction No copper parts larger than 2 inches along winding direction No electrical continuity through cooling tubing Fits in 0.08 inch envelope laterally and radially (not including tube) structure winding vessel PFCs

NCSX June 10-11, 2004NCSX modular coil cooling workshopB. Nelson 7 Baseline cooling concept, cladding fabrication structure winding vessel PFCs

NCSX June 10-11, 2004NCSX modular coil cooling workshopB. Nelson 8 Cladding to chill plate joint structure winding vessel PFCs

NCSX June 10-11, 2004NCSX modular coil cooling workshopB. Nelson 9 Difficulties