APEX
Considerations for Heating and Diagnostic Penetrations
presented by B. Nelson
APEX Meeting
UCLA
Nov 2, 1998
Presentation Outline
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• For Heating / Current drive, Vacuum pumping
and Diagnostics
What did ITER propose?
How are we different?
What are our options?
Recommendations
Heating Systems – What did ITER propose?
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• ITER used as a starting point because it is the first device to consider long pulse DT
operation
• ITER proposed a full complement of heating systems, including
Neutral Beam Injection
ICRF
ECRF
• Each System delivers 50 MW
• Systems were constrained to occupy midplane port openings
• ITER data taken from DDDs for Vacuum vessel (WBS 1.5), blanket (WBS 1.6) and
diagnostics (WBS 5.5)
NBI
What did ITER propose?
_______________________________________________________________________
Purpose
Heating, current drive, profile control, plasma rotation
No. of ports
Toroidal location of ports
Size of opening
Aiming angle
Power density
3
3 adjacent ports
580 x 1000 mm
tangent to R=6.5 m
~ 29 MW/m^2
NBI and APEX
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Potential Problems for APEX
Forming a tangential hole
Providing adequate shielding for magnets
Charge exchange of neutrals at opening
Extension of confinement boundary
Recommendation
Avoid NBI
Avoid tangential NBI, unless all ports are tangential
ICRF What did ITER propose?
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Purpose
Heating, current drive, profile control
No./size of ports of ports
Power density
First ceramic break proximity
4 @ 2700 x 1800 m
~ 3 MW/m^2
bioshield
ICRF and APEX
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• Constraints / Potential Problems
- Multiple adjacent ports/current straps needed for current drive
- Liquid metal flowing on front, may produce arcing, shorting of current strap
- Absorption of power by walls, other losses
Electron
- Must be close to plasma edge for good coupling
heating
only
• Options
- Poloidal location can vary, but cannot be “too near
divertor’, vertical only good for electron heating
- Folded waveguide has much higher (~ 4x) power
density, no current straps
- IBW can use horizontal orientation of waveguides,
Fastwave requires vertical array
- Flibe is probably better than lithium
• Recommendation
FWG near top of single null configuration, assume 10 MW/m^2
OK
ARIES and RF Heating
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RF Launchers located at midplane port of sector module
ITER ECRF
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Purpose
Heating, current drive, profile control
No. / size of of ports
Power density
Aiming mirror proximity
1 @ 1800 x 2700 mm
~ 10 MW/m2
~ 1 m from first wall
ECRF and APEX
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• Constraints / Potential Problems
- Arcing, (like microwave oven)
- Absorption of power by walls, other losses
- Mirror surface lifetime
• Options
- Poloidal location can vary, but cannot be vertical
due to resonance along constant Btoroidal
• Recommendation
Numerous small waveguides located near top of
single null configuration
Cannot be
vertical
Vacuum Pumping – What did ITER propose?
_______________________________________________________________________
Purpose
Divertor pumping, initial evacuation
No. / size of of ports
Pump type
12 @ 2m2 each, pumps through divertor
cryopump in each duct
Vacuum Pumping and APEX
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Vacuum Pumping completely tied to divertor configuration and operation
Should be possible to integrate with various concepts, may not require hole in FW
Diagnostics – What did ITER propose?
_______________________________________________________________________
• ITER is an experimental device, and requires many types of diagnostics
40 separate systems grouped in seven categories:
Magnetic diagnostics
Neutron diagnostics
Optical / IR systems
Bolometric Systems
Spectroscopic and NPA systems
Microwave Diagnostics
Plasma Facing Components and Operational Diagnostics
• Three levels of importance are envisioned
1. Minimum set for machine protection and control
2. Additional set for Advanced Tokamak operation
3. Additional set for physics studies and evaluation
• This is a very complicated subject
Table 7-II. Priorities for Control Measurements
GROUP 1a
Mach. Protect. & Basic Control
Parameter
Shape/Position
Locked Modes
q(a), q(95%)
Plasma Current
Beta
m=2 Mode
’Halo’ Currents
Loop Voltage
Impurity Influx
(main plasma &
divertor)
GROUP 1b
Advanced Control
GROUP 2
Evaluation & Physics
Diagnostic
Magnetics
Parameter
MHD Activity
Diagnostic
Magnetics
ECE
Reflectometry
Parameter
Fishbones,
TAE Modes
Diagnostic
Magnetics
Impurity Monitors
Shape/Position
(very long
pulse)
Reflectometry
(plasma posit.)
Confined
α-Particles
Collect. Scatt.,
Knock-on Tail
Neutr. Spectr.,
Gamma Spectr.
NPA, Hα Spec.,
Two-Photon
Ly-a Fluoresc.
Hα Spectrosc.
Runaway Electrons Hard X-Rays,
Synchrotron
Radiation
Line-averaged
Interf./Polarim.
Density
Jsat (divertor)
Tile Shunts
Neutron Profile, Rad. Neut. Cam., nT/nD/nH
α -Source
Vert. Neut. Cam. (edge)
Profile
CHERS
nT/nD/nH (div)
nHe Profile
Te Profile
(edge)
Thomson Scatt.
(edge)
ne, Te Profiles
(X-point)
Thomson Scatt.
(X-point)
ne, Te (plate)
Langmuir Probes
Plasma Rot.,
Ti Profile,
Impurity Profile
Te Prof. (core),
ne Prof.(core)
CHERS,
X-Ray Crystal
Spectroscopy
LIDAR (main),
ECE
Bolom. Array
(main pl. & div.)
Ti Profile
(core)
Radial Neutron
Spectrometer
Neutron Flux
Monitors
nT/nD in Plasma
NPA, Fast wave
Core
Reflectometry
Zeff Line-Aver.
Vis. Continuum
(single channel)
H/L Mode Indicator Hα Spectrosc.
(typ. channel)
ELMs
ECE, Refl.(main)
ne Profile
(edge)
q Profile
Reflectom. (main) Ti in Divertor
Surf. Temp.
(divertor plates &
first wall)
Rad. Power from
Core, X-point and
Divertor
Neutron Flux
IR Cameras
Gas Pressure (div. Pressure Gauges
& duct)
Gas Composit.
(div. & duct)
Toroidal Magnetic
Field
RGAs
Current Shunts
Prad Profile
Zeff Profile
nHe (divertor)
Heat
Deposition
Profile in Div.
Div. Ionization
Front Position
Neutral Density
(near wall),
Particle Source
ne, Te (divertor)
MSE,
Polarim. System
Bolom. Arrays
(main pl.& div.)
Visible Cont.
Array
RGA,
Laser Induced
Fluoresce. (LIF)
IR Camera
Vis . Spectrom.,
Bolometry
Hα Spectrosc.
(many chann.)
Reflect. (div)
ECA (div.)
Alpha Loss
Alpha-Loss Det.
Neutr. Fluence Neutr. Act. Syst.
ELMs
ECE, Refl.(main)
Sawteeth
ECE, Soft X-Ray
Array
Erosion (plate) Imp. Monitors,
Reflectometry
From ITER Physics Basis Document, Chapter 7.
Plasma Flow
(div)
Pellet Ablation
Te Fluctuations
ne Fluctuations
Radial E Field
and E Fluctuat.
Imp. Monitor.
(div)
Imp. Monitor.
(div)
Hα Spectrosc.
ECE, Soft X-Ray
Array
Reflectometry,
Microw. Scatt.
CHERS (plasma
rot.)
Edge Turbulen. Reflectometry
MHD Activity
in Plasma Core
ECE, Soft X-Ray
Array
Diagnostics – What is interface with FW / Blanket?
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• Some diagnostics require unobstructed line-of-site view of the plasma
(e.g. neutral partical analyzers, vacuum ultraviolet and X-ray spectroscopy)
- The detection equipment must be inside the plasma vacuum boundary, but outside
the biological shield
- The holes in the first wall are small, 20 to 30 mm should be adequate, ITER uses
slots for 2-D scans
- The site line behind the hole will be larger, and represents hole in shield
• Most diagnostics are isolated
with a vacuum window, and
transmit signals via reflective
optics (mirrors) for the first 2 m
from the plasma
From ITER Diagnostics DDD
Diagnostics – ITER examples, Magnetics
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Diagnostics – ITER examples, top port
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Impurity monitors, bolometry
Spectroscopy
Diagnostics – ITER examples, top port
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Thomson Scattering
Neutron Camera
Diagnostics – ITER examples, divertor cassette
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With waveguides
With IR TV viewing ports
Central Diagnostic Divertor Cassette
Diagnostics – ITER examples, divertor cassette
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VUV spectroscopy in diagnostic cassette
Diagnostics – What must APEX accomodate?
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• Minimum set of machine protection, plasma stability, and control diagnostics
Magnetic loops, impurity monitors, bolometers, IR cameras, neutron flux monitors,
pressure gauges, RGAs, X-ray monitors, interferometers
• Possible additional set for control of advanced operating modes
ECE, reflectometers, LIDAR
• Viewing system for inspection and maintenance
• Component instrumentation
Coolant flowrate, temperature; structure temperature, deflection, vibration
Diagnostics – What must APEX accomodate?
________________________________________________________
• One possible list:
GROUP 1a
Mach. Protect. & Basic Control
Parameter
Shape/Position
Locked Modes
q(a), q(95%)
Plasma Current
Beta
m=2 Mode
’Halo’ Currents
Loop Voltage
Impurity Influx
(main plasma &
divertor)
Diagnostic
Magnetics
Impurity Monitors
Runaway Electrons Hard X-Rays,
Synchrotron
Radiation
Line-averaged
Interf./Polarim.
Density
Jsat (divertor)
Tile Shunts
Surf. Temp.
(divertor plates &
first wall)
Rad. Power from
Core, X-point and
Divertor
Neutron Flux
IR Cameras
Bolom. Array
(main pl. & div.)
Neutron Flux
Monitors
nT/nD in Plasma
Core
Zeff Line-Aver.
NPA, Fast wave
Reflectometry
Vis. Continuum
(single channel)
Gas Pressure (div. Pressure Gauges
& duct)
Gas Composit.
RGAs
(div. & duct)
Toroidal Magnetic Current Shunts
Field
Plasma chamber
condition
Visible inspection
GROUP 1b
Advanced Control
What is the
Parameter
interface?
Magnetic loops, MHD Activity
coils near or
inside last
conducting
surface
Small opening,
mirrors/lenses
through fibers to
PM tubes
Small opening to
X-ray detector,
IR camera
Waveguide inlet
and exit
Could be
retractable probe
Could be small
periscope
Diagnostic
Magnetics
ECE
Reflectometry
Shape/Position
Reflectometry
(very long pulse) (plasma posit.)
Evacuated tube
Te Prof. (core),
ne Prof.(core)
Tube w/window,
Horn with
detector
Evacuated tube
LIDAR (main),
ECE
Ti Profile (core)
Radial Neutron
Spectrometer
ne Profile (edge) Reflectom.
Evacutedtbe
(main)
Prad Profile
Bolom. Arrays Evacuated tubes
(main pl.& div.)
evacuated tube
Zeff Profile
Visible Cont.
Array
Thin spot in
shield
nHe (divertor)
RGA,
Laser Induced
Fluoresce. (LIF)
IR Camera
Evacuated tube
to RGA
Heat Deposition
Profile in Div.
Div. Ionization
Front Position
Below divertor ne, Te (divertor)
or in duct
Alpha Loss
Telescoping
mast or
periscope
What is the
interface?
Loops,
Evacuated
waveguide
Tube to mirrors
Evacuated tube
Laser port and
viewing port
Could be small
periscope
Vis . Spectrom., Evacuated tube
Bolometry
Reflect. (div)
Evacuated tube
ECE (div.)
Alpha-Loss Det.
Neutr. Fluence
Neutr. Act. Syst. rabbits
ELMs
ECE, Refl.(main) Horn with
detector
ECE, Soft XHorn with
Ray Array
detector
Sawteeth
Erosion (plate)
Imp. Monitors,
Reflectometry
Small opening,
mirrors/lenses
through fibers to
PM tubes
Diagnostics – Recommendations for APEX
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• Restrict diagnostics to minimum set for machine protection and control
• Magnetic Diagnostics
Solution not obvious for thick lithium walls
• Other diagnostics
- Restrict to small openings in standard location, eg near top,
(Use concept of diagnostic cassette, if possible)
- For NPA, VUV, etc. assume 20mm dia clear opening through FW
- Assume reflective optics for spectrometers and IR TV, and provide sufficient
radiation and debris protection of mirrors and windows
Conclusions
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• Any APEX configuration will require access to the plasma for heating, diagnostics,
and vacuum pumping
• ITER has investigated these functions for long pulse DT operation
• Some preliminary conclusions can be drawn
- Avoid NBI
- ECRF and ICRF (FWG) have comparable power densities, ~ 10 MW/m^2 and
can be launched near the top of a single null configuration
- Vacuum pumping interface depends on divertor configuration
- Diagnostics are complicated, but most can interface through relatively small
opening in the first wall, 20 to 30 mm in dia, or slots with this width