1. Diagnostics WBS 3 D. Johnson with input from: T. Brown, H. Neilson, H. Takahashi, and M. Zarnstorff Princeton Plasma Physics Laboratory M. Cole, E. Lazarus, Oak Ridge National Laboratory M. Fenstermacher, Lawrence Livermore National Laboratory Review of NCSX Conceptual Design PPPL May 21-23, 2002

2. DWJ-0205212 NCSX Diagnostic Plan - Outline 1.An integrated diagnostic plan is necessary at an early stage to determine requirements for many aspects of the facility, and to estimate resource needs after the device is built. 2.Diagnostic access has been given high priority in the Conceptual Design of NCSX, and appears adequate. 3.Specific diagnostics deserve comments. Project - magnetics, visible cameras, interferometer, e-beam mapping Upgrade - SXR arrays, active spectroscopy, Thomson scattering 4.Diagnostic integration is an ongoing, critical process with impacts on details of vacuum vessel, PFCs, modular coils, cryostat and other elements.

3. DWJ-0205213 Diagnostic Planning Philosophy Research Plans  Measurement Needs  Diagnostics Diagnostics included as part of the Project are those needed to verify basic operation of machine. Machine design needs to demonstrate that it can support the full complement of diagnostics needed for the research program. Phased diagnostic implementation is a significant effort following device completion, and needs to be anticipated.

4. DWJ-0205214 Checkout Phases Diagnostics that are part of the Construction Project

5. DWJ-0205215 3. Ohmic

6. DWJ-0205216 4. Auxiliary Heating

7. DWJ-0205217 5. Confinement and Beta Push plate ne, Te

8. DWJ-0205218 6. Long Pulse

9. DWJ-0205219 Planned Work on Upgrade Diagnostics Precedes First Plasma

10. DWJ-02052110 Diagnostic Infrastructure Needs Infrastructure needs (eg. AC power, cable trays, data acquisition, platform space, shutter pneumatics, etc): –Have been budgeted in other WBS areas for diagnostics in Construction Project (red) –Have been anticipated for upgrade diagnostics.

11. DWJ-02052111 Diagnostic Areas Several rooms adjacent to the NCSX Cell have been reserved for diagnostic use. Diagnostics with fiber coupled detectors, sensitive to x-rays and gammas, can be located behind radiation shield. (eg. TS, CHERS, MSE, visible spectroscopy) NCSX Cell

12. DWJ-02052112 Diagnostic Access Influenced Core Design Current design with 18 TF coils over modular coils optimizes diagnostic access. Port extensions positioned on radial planes where they would clear modular coils, TF and PF coils. In many locations, it may be possible to deviate from radial planes, in order to optimize sightlines or views. Impact on cryostat interface and machine assembly will be assessed.

13. DWJ-02052113 Conformal Cryostat Provides Flexibility for Diagnostic Access Close-fitting, conformal cryostat features removable panels that can be tailored to diagnostic space needs. This will permit some port extensions to be made shorter, and will open up more space within the cryostat perimeter.

14. DWJ-02052114 Preliminary Diagnostic Port Allocation

15. DWJ-02052115 Access Summary The number of ports available for diagnostics appears adequate: –96 ports, including 4 for neutral beam injectors –Currently ~ 60 allocated to the diagnostics in this plan –Can accommodate auxiliary systems (fueling, wall conditioning, etc.) and future diagnostic needs The orientation of the ports has not been optimized for specific diagnostic views. Long port extensions will drive diagnostic design to compact, re-entrant assemblies.

16. DWJ-02052116 Magnetics for Plasma Control As part of preliminary design, numerical modeling will be used to determine optimum number, type and location of magnetic sensors needed to control plasma evolution. For budgetary purposes, estimate that ~ 100 sensors will be needed in initial installation, including flux loops, saddle loops, diamagnetic loops, Rogowskis and B-dot probes. Cost estimate is $914k, covering –Physicist interaction iterating with modeling effort –Modifications of existing (NSTX) high temperature, high vacuum sensor designs including shields –Design for high reliability sensors between outer vacuum vessel and modular coils –Designs of mounts for a variety of geometries –Careful documentation of sensor location and wiring –Purchase 100 integrators, cabling

17. DWJ-02052117 Space for Magnetic Sensors 25 mm 50 mm Clearances on the inside and outside surfaces of the vessel are adequate for magnetic sensors. Details of sensor and sensor lead integration with vessel thermal insulation on the outside, and PFC support structure and heat shields on the inside TBD.

18. DWJ-02052118 Visible Cameras Plan calls for three re-entrant, shuttered windows, with tangential, wide-angle views. Shutters required because of requirement for bakeout and between shot GDC during initial phase. Coherent fiber bundles will be used to relay image out of high field region. Cooling may be needed to protect optics during bakeout. Each view is equipped with a fast-framing CCD camera (full frame rate > 1 kHz) and associated PC, etc. Cost with contingency is $305k. Savings may be possible if non-re- entrant window on beam ports available with adequate view.

19. DWJ-02052119 Possible Camera View from Beam Port View taken from this location looking into the port Limiter Location

20. DWJ-02052120 Interferometer Plan based on 1 mm microwave system with solid-state source and mixer, similar to those implemented on DIIID and Pegasus by UCLA. (soon to be implemented on NSTX) Uses a shuttered, re-entrant quartz window with external optics to image the source on a reflector mounted on inside wall. In later phases, this diagnostic will be used to normalize Thomson scattering density profiles, and so it will have a beam geometry equivalent to the Thomson laser. Cost is $219k, with contingency.

21. DWJ-02052121 Field Mapping Traditional technique involves an electron beam that lights up a fluorescent mesh or movable fluorescent rod as it makes many traverses along a field line. Light is detected by a CCD camera, with rather inefficient collection of fluorescence. To increase the sensitivity and time response, investigating other methods which gather more of the light from the mesh or rod by collecting the light locally. Estimate of $538k, with contingency, is based on scanning e-beam, and scanning fluorescent probe with large linear array of vacuum compatible fibers to collect and transmit emitted light to window, where a CCD will detect. Probe is to be deployable without breaking vacuum, and aims at a spatial resolution of 2 mm. Modeling of vacuum scenarios to be probed will help refine requirements.

22. DWJ-02052122 Soft X-Ray Tomography Detailed characterization of the field topology is a diagnostic challenge for NCSX. Considering many (~10) compact, vacuum compatible, SXR arrays (16 ch./array) for tomography. Eventually at two toroidal locations. Nominal 50 mm minimum clearance between back of PFCs an vessel is inadequate for current SXR array designs. It may be possible to integrate adequate clearance for arrays as well as cooling etc. into the design of vessel spacer.

23. DWJ-02052123 Heating Beam Geometry Unfavorable for Active Spectroscopy For good spatial resolution, CHERS and MSE require sightlines ~ tangent to flux surfaces which intersect beam over small  r. This is impossible when the beam is also ~ tangent to surfaces. A diagnostic neutral beam will be necessary for active spectroscopy. Currently assessing DNB requirements.

24. DWJ-02052124 Thomson Scattering ECE radiometry will be difficult for T e (R,t) profile measurements  high repetition rate TS capability highly desirable. Achieving high spatial resolution would also be extremely valuable for many experiments, including studies of T e “ filaments,” transport barriers, and island formation. One strategy, recently adapted by MAST, is to design a high throughput viewing system with good spatial resolution, and the capability of simultaneously imaging both a high rep rate Nd:YAG laser and a ruby laser. Both capabilities could be developed over time. Another strategy being pursued at JET, would be to develop cheaper (perhaps highly multiplexed) versions of polychromator/APD/digitizer detectors. Both strategies require high throughput viewing system for good S/N.

25. DWJ-02052125 Viewing Access at Bullet Plane for Thomson Scattering and Active Spectroscopy With ports on radial plane, high throughput viewing access at bullet plane is problematic for TS or CHERS/MSE. Out-of-radial-plane ports may provide such access, while avoiding coils. In the next year, such studies are needed to optimize access for specific diagnostics before vessel design frozen. Laser or DNB Non-radial port

26. DWJ-02052126 Most Urgent Task is to Optimize Port Extensions Port extensions in existing designs: –Lie in radial planes –Have lengths defined by cylindrical cryostat Both of these constraints could be relaxed to improve diagnostic access. This should be done with specific diagnostics in mind.

27. DWJ-02052127 Measurement Requirements will be Useful in Evaluating Diagnostic Concepts

28. DWJ-02052128 Diagnostics Will be a Collaborative Effort As this plan evolves, it will clearly benefit from community input. Diagnostics are an entry point for establishing collaborative participation in NCSX, as they have on NSTX and many other devices. Diagnostic Working Groups should be an important component of the Research Forums, which will begin in FY2005. Need to identify experts interested in developing NCSX diagnostics.

29. DWJ-02052129 Summary A diagnostic plan has been developed which is phased to satisfy the needs of the research program. The access available for diagnostics appears to be adequate, but further optimization of port extensions is required. Using recent experience on NSTX as a basis, cost estimates for magnetics, cameras, interferometer and field mapping diagnostics have been developed. Longer term resource needs for diagnostics have also been planned based on phased implementation. Ongoing near-term diagnostic integration effort is planned to optimize core device design to benefit diagnostic access, to further define measurement requirements, and to seek and encourage new diagnostic development that might benefit NCSX.