Development of the NCSX Reference Design: Progress, Status, Plans

1
Development of the NCSX Reference
DesignProgress, Status, Plans

• Wayne Reiersen and the NCSX Project Team

2
NCSX Status at PAC-3

• C82 plasma configuration
• Conformal vacuum vessel
• Saddle coils wound in grooved shell
• PBX-M TF and PF coils re-used

• Issues
• High current density in saddle coils limited
  achievable field and pulse length
• Flexibility and heating diagnostic access
  unexplored
• Other (possibly better) coil topology options
  unexplored

3
Goals for FY00

• Address problem of high current density in saddle
  coils
• Investigate plasma configurations with lower
  current density and coil complexity
• Develop and apply coil design tools to reduce
  current density
• Perform RD to quantify allowable ?T
• Explore alternate coil topologies
• Demonstrate adequate access for heating and
  diagnostics

4
Progress in FY00

• New plasma configurations developed with better
  physics and easier coils Zarnstorff, Reiman
• Great progress made in developing coil
  optimization tools (CoilOpt, NESCVD/GA, TiltOpt)
  Hirshman
• Studies on PBX investigated generic engineering
  issues (VV, PFCs, diagnostics) Nelson
• Access study of saddle coils in PBX option to be
  marginally OK Nelson
• New machine configurations developed for saddle
  coil, modular coil, and smarter background coil
  options Nelson
• RD results gave basis for higher conductor DT
  Nelson

FOR MORE INFO...
Refer to referenced talks.
5
Coil Topology Studies

• Saddle coils in PBX (c82)
• Potential cost savings
• Access is marginally OK
• Current density is too high
• Limited space for shape flexibility

• Smarter background coils (c82)
• Reduces current density by 60
• NB access and stray fields in vicinity of
  beamlines are concerns

• Modular coils (c82)
• Substantially lower current density, perhaps
  avoiding pre-cooling below ambient
• More space for shape flexibility
• Fabrication (min. radius of curvature) and access
  are concerns
• Commonly viewed as reactor relevant

• Improved plasma configurations
• Result in smoother coils and lower current
  density for saddles and modulars

6
The Candidates

• Saddle and modular coils both show promise as
  viable design solutions for the new plasma
  configurations
• Smarter background field coil options will be
  explored as a lower priority
• No longer required to get current density back
  in the box
• Less design freedom and upside potential with
  stray field constraints
• Compulsory and differentiating design features
  are being assessed to guide the selection of a
  reference machine configuration

7
Compulsory Design Features

• Satisfy reference scenario requirements
• 2T field on axis
• Adequate physics performance throughout discharge
• Good surfaces
• Adequate confinement to achieve high (gt4) beta
• Stable to kink and ballooning modes
• Quasi-axisymmetry
• Timing requirements

• Provide adequate access for diagnostics and
  plasma heating
• 6 MW NBI (all co -gt balanced)
• 6 MW HHFW (upgrade)
• Satisfy minimum requirements for flexibility (TBD)

8
Differentiating Design Features

• Experimental flexibility
• Surface quality robustness
• Pulse length
• Design margins
• RD required to establish feasibility
• Fabrication and assembly risks
• Maintainability and operability
• Cost

9
Future Plans

• Select reference plasma configuration (August
  00)
• Continue development of saddle and modular coil
  options and assessment of design features
  select reference machine configuration (September
  00)
• Develop pre-conceptual design for PVR, including
  cost schedule estimates (December 00)
• Update design and cost schedule estimates for
  Design/Cost/Schedule Review (April 01) to
  support FY03 project start