DiagnosticsWBS 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

DWJ-020521

2

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.

DWJ-020521

3

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.

DWJ-020521

4

Checkout Phases

1. Initial Operation

• initiate plasma: exercise coil set plasma current plasma current Roqowskis

Ip >25 kA conductivity flux loops

checkout vacuum diagnostics plasma position saddle loops

checkout magnetic diagnostics total stored energy B-dot probes

initial wall conditioning diamagnetic loop

plasma/wall imaging fast visible cameras

line integrated density 1 mm interferometer2. Field Line Mapping

• map flux surfaces vacuum flux surfaces e-beam probe

verify iota and QA variable energy trace particles fluorescent rod probe

high dynamic range CCD

Diagnostics that are part of the Construction Project

DWJ-020521

5

• initial plasma control, plasma evolution control electron density profiles multichord FIR interf./ polarim.

global confinement & scaling, effect of 3D shaping electron temperature profiles Thomson scattering

density limit & mechanisms radiated power profiles core foil bolometer array

study of Te and ne profiles. magetic axis position compact SXR arrays

• vertical stability low (m,n) MHD (<100kHz)

current-driven kink stability flux surface topology

effect of low-order rat. surf. on flux-surface topology impurity species visible spectrometer

• initial study of effect of trim coils, both signs impurity concentration abs. UV spectroscopy

• effect of contact location on plasma edge & recycling Zeff filtered 1D CCD camera

initial attempts to control plasma contact location hydrogen recycling visible filterscopes

3. Ohmic

DWJ-020521

6

4. Auxiliary Heating

• test of kink & balooning stability at moderate beta ion temperature profile diagnostic neutral beam

effect of shaping on MHD stability toroidal rotation profile toroidal CHERS

initial study of Alfvenic modes w/ NB ions poloidal rotation profile poloidal CHERS

• confinement scaling w/ iota, B, … radial electric field MSE polarimeter

local transport measurements, perturb. meas. iota profile

• test of quasi-symmetry on confinement and transport fast ion loss fast ion loss probe

• density limits and control with heating ion energy distribution neutral particle analyser

use of trim coils to minimize rotation damping neutron flux epithermal neutron detector

blip measurements of fast ion conf. and slowing down first wall surface temperature compact IR cameras

initial attempts to obtain enhance confinement regimes high frequency MHD(<5Mhz) high frequency Mirnov coils

• pressure effects on surface quality fast tang. x-ray pinhole camera

controlled study of neoclassical tearing using trim coils enhanced x-ray tomography

• wall coatings with aux. heating SOL tmperature and density moveable Langmuir probe

• edge and exhaust charact. with aux. heating neutral pressure neutral pressure gauges

• attempts to control wall neutral influx target Te, ne plate mounted Langmuir probes

wall biasing effects on confinement

DWJ-020521

7

5. Confinement and Beta Push

l stability tests at beta >~ 4% radial electric field divertor foil bolometer arrays

l detailed study of beta limit scaling edge/div. radiated power profile divertor filtered CCD cameras

l detailed studies of beta limiting mechanisms core helium density fast IR camera

disruption-free operating region at high beta He CHERS system (with DNB)

active mapping of Alfvenic mode stability (with antenna) plate mounted Langmuir probes

enh. conf.: H-mode, hot ion modes, RI mode, pellets divertor thermocouples

l enhanced confinement, rotation effects divertor UV spectroscopy

l scaling of local transport and confinement fluctuation diagnostics TBD

turbulence studies

scaling of power or other thresholds for enh. conf.

ICRF wave propagation and damping (possible)

perturbative RF measurements of transport (possible)

l divertor operation optimized for power handling

trace helium exhaust and confinement

scaling of power to divertor

l control of high beta plasmas and their evolution

plate ne, Te

DWJ-020521

8

6. Long Pulse

long pulse plasma evolution control more detailed divertor profiles divertor Thomson scattering

equilibration of current profile divertor diagnostics (TBD)

beta limits with ~ equilibrated profiles

edge studies (3nd generation wall)

long-pulse power and particle exhaust w/ div. pumping

compatibility of high conf., high beta, and div. ops

DWJ-020521

9

Planned Work on Upgrade Diagnostics Precedes First Plasma

DIAGNOSTIC 3 4 5 6 7 8 9 10 11 12

diagnostic integration 28 142 171 171 57 0 0 0 0 01. Initial Operationmagnetics 40 40 40 320 360 0 0 0 0 01 mm interferometer 0 0 0 125 54 0 0 0 0 0visible cameras 0 0 0 172 74 0 0 0 0 02. Field Mapping

e-beam mapping 0 0 22 266 155 0 0 0 0 03. Ohmic

Thomson scattering 0 0 0 569 325 325 406 0 0 0multich. FIR interf./ polarim. 0 0 0 60 360 180 0 0 0 0compact SXR arrays 0 0 0 126 126 63 0 0 0 0core foil bolometer array 0 0 0 0 60 60 0 0 0 0

visible spectrometer 0 0 0 39 39 52 0 0 0 0abs. UV spectroscopy 0 0 0 65 65 86 0 0 0 0filtered 1D CCD camera 0 0 0 32 32 43 0 0 0 0visible filterscopes 0 0 0 12 28 0 0 0 0 04. Initial Aux. Heatingadditional magnetics 0 0 0 0 0 200 200 0 0 0diagnostic neutral beam 0 0 0 70 420 210 0 0 0 0MSE polarimeter 0 0 0 0 0 50 300 150 0 0toroidal CHERS 0 0 0 40 240 120 0 0 0 0poloidal CHERS 0 0 0 0 0 50 300 150 0 0enhanced x-ray tomography 0 0 0 0 0 250 250 0 0 0

DWJ-020521

10

Diagnostic Infrastructure Needs

DIAGNOSTIC DESCRIPTION WBS CHAN SPEED PORT WIND SHUT

ELEC FDTH

MECH FDTH

TIV RACK

1. Initial Operation

magnetics 100 sensors + integrators, etc 31 100 100 kHz 12 200 3visible cameras 3 cameras (1 fast) with filters 361 3 frm grb 3 3 3 11 mm interferometer with inner wall reflector 350 2 200 kHz 1 1 1 12. Field Mapping

e-beam probe retractable, radially scanning 38 4 10 kHz 1 6 2 1 0.5fluorescent rod probe retractable, pivoting 38 4 10 kHz 1 2 2 1 0.5high dynamic range CCD standard frame rate 38 2 frm grb 1 2 2 0.53. Ohmic

Thomson scattering ultimate 60 spatial ch., 100 Hz 351 100 500 MHz 2 2 2 4multich. FIR interf./ polarim. # chords, λ, geometry TBD 356 24 100 kHz 1 2 2 4

compact SXR arrays 3 16 arrays of channels 341 48 200 kHz 1 48 3 1 core foil bolometer array 16 channel array 334 16 10 kHz 1 32 1 0.5

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.

DWJ-020521

11

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)

K2 COLUMN

MACHINE

CENTERLINE

MACHINE CENTER LOCATED

FROM COLUMN "N-2"

37'—6"

68'—0"

NCSX Cell

DWJ-020521

12

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.

DWJ-020521

13

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.

DWJ-020521

14

Preliminary Diagnostic Port Allocation

1AOT

1AOB

1A6TL 1A6T 1A6TR

1A6BL 1A6B 1A6BR

1A14L 1A14R1A6M 1BO

1B8I

1B8B

1CO

1C14

1C6

1F8T

1F8I

1F0

1E6

1E14

1EO

1D2IN

1D2T

1D6TL

1D6TM

1D6BL

1D6TR

1D6MR

1D6BR

1D2B

A B C D E F

1AOTdiv bolometer div camera 1A14L

neutral heating beam 1AOB

div. Bolometer IR camera 1BO

multichannel interf./ polarim. 1C0 1D2T 1D2B 1E6 magnetics 1F8T magnetics

1A6TL 1A6M 1A6BL 1B8Ihigh frequency Mirnov coils 1C12 1D6TL

x-ray tomography 1D6BL

x-ray tomography 1E12 TS view 1F8I

1A6Tdivertor thermocouples 1A14R

fast tang. Xray camera 1A6B

divertor UV spectrometer 1B8B magnetics 1C6 magnetics 1D6TR

x-ray tomography 1D6BR

x-ray tomography 1EO 1F0

1A6TR 1A6BR 1D6ML TS laser 1D6MRvisible filterscope

1D2IN TS dump

2AOT divertor TS 2A14L visible camera 2AOB divertor TS 2BOfluorescent rod probe 2C0 2D2T 2D2B 2E6 magnetics 2F8T magnetics

2A6TL 2A6M 2A6BL 2B8I 2C12 2D6TLmovable Langmuir probe 2D6BL

high frequency Mirnov coils 2E12

CHERS, MSE, He CHERS view 2F8I

2A6Tvisible filterscope 2A14R visible camera 2A6B

visible filterscopes 2B8B magnetics 2C6 magnetics 2D6TR

visible spectroscopy 2D6BR

UV spectroscopy 2EO 2F0

fluctuation diagnostic

2A6TR 2A6BR 2D6ML DNB 2D6MR e-beam probe

2D2IN DNB dump

3AOTplate probes thermocouples 3A14L visible camera 3AOB fast IR camera 3BO

fluctuation diagnostic 3C0 3D2T 3D2B 3E6 magnetics 3F8T magnetics

3A6TL 3A6Mhigh frequency Mirnov coils 3A6BL

fast neutral pressure gauges 3B8I

fast ion loss probe 3C12

fluctuation diagnostic 3D6TL

x-ray tomography 3D6BL

x-ray tomography 3E12 3F8I

3A6T visible camera 3A14Rneutral heating beam 3A6B

divertor visible camera 3B8B magnetics 3C6 magnetics 3D6TR

x-ray tomography 3D6BR

x-ray tomography 3EO 3F0

3A6TR 3A6BRfast neutral pressure gauges 3D6ML core bolometer 3D6MR

fast scanning edge probe

3D2IN

Period 3

A B C D E F

Period 1

Period 2

DWJ-020521

15

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.

DWJ-020521

16

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

DWJ-020521

17

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.

DWJ-020521

18

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.

DWJ-020521

19

Possible Camera View from Beam Port

View taken from this location looking into the port

Limiter Location

DWJ-020521

20

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.

DWJ-020521

21

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.

DWJ-020521

22

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.

QuickTime™ and aNone decompressor

are needed to see this picture.

DWJ-020521

23

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.

DWJ-020521

24

Thomson Scattering

• ECE radiometry will be difficult for Te(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 Te “ 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.

DWJ-020521

25

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 DNBNon-radial port

DWJ-020521

26

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.

DWJ-020521

27

Measurement Requirements will be Useful in Evaluating Diagnostic Concepts

DWJ-020521

28

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.

DWJ-020521

29

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.