28/29 october 2008colloquium on iter-codac1 examples of iter codac requirements for diagnostics s....
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28/29 October 2008Colloquium on ITER-CODAC 1
Examples of ITER CODAC requirements for
diagnosticsS. Arshad
Colloquium on ITER-CODAC Plant Control Design Handbook
and EU Procurement of Control and Instrumentation for ITER
28 October 2008
28/29 October 2008Colloquium on ITER-CODAC 2
Hot fusion plasma can be contained in a magnetic field
28/29 October 2008Colloquium on ITER-CODAC 3
JET: World’s largest tokamak
ITER
R (m) 6.2
a (m) 2
IP (MA) 16
Bt (T) 5.3
Paux (MW) 40 – 90
P (MW) 80+
Q (Pfus/Pin) 10
Prad (MW) 48
tpulse (s) 400+
R a
New engineering and physics challenges for measurement and control
Containment improves with size – ITER will be much larger than today’s machines
28/29 October 2008Colloquium on ITER-CODAC 4
UPPER PORT 11• Edge Thomson
UPPER PORT 10 • X-Ray Survey • Imaging VUV Spectroscopy
EQUATORIAL PORT 9• MSE• Toroidal
Interferometer / Polarimeter
• ECE• Wide Angle TV/IR
Port type
EQUATORIAL PORT 11• X-Ray Crystal Spectroscopy, array• Divertor VUV Spectroscopy• X-Ray Survey• Core VUV Monitor• Neutral Particle Analyser• Reflectometry
DIVERTOR PORT 8• Divertor
Reflectometry
DIVERTOR PORT 10• X-point LIDAR• Divertor Thomson
Scattering• H-Alpha Spectroscopy
Wide range of diagnostics needed to diagnose fusion plasma
No. usedEquatorial 9Upper 12
Lower 9
Additionally many measurements inside vessel
28/29 October 2008Colloquium on ITER-CODAC 5
The EU will supply a range of diagnostics to ITER
Analog processing ADC
Off-line processing
Real-time processing
ControllerMachine protection & plasma control
Physics studies
Ports for diagnostics & heating systems General scheme for processing of diagnostic data
Processed data from diagnostics (Courtesy of EFDA-JET)
Plasma shape & neutron profile
Plasma wall interaction
Temperature & density profiles
• Wide-angle viewing system • Magnetics• Radial neutron camera• Core Thomson scattering • Bolometers• Core charge exchange recombination spectrometer• Hard X-ray monitor• Plasma position reflectometer• Pressure gauges• Thermocouples• LFS collective Thomson scattering• High-resolution neutron spectrometer• Gamma-ray spectrometers
About 40 diagnostic systems installed in ports and inside / outside the toroidal chamber; 13 to be supplied by the EU:
28/29 October 2008Colloquium on ITER-CODAC 6
The magnetics diagnostic is a large system for basic plasma control, machine protection and physics studies
• Diagnostic comprises pick-up coils, flux loops, Rogowski coils
• ~1050 sensors inside the vessel (shown in figure)
• ~600 additional sensors outside vessel
In-vessel pick-up coil
Copper Core
Polyimide ribbon
Glass fibre fillerGlass fibre filler
1st Copper layer(=5.5 mm,pitch=1mm)
Glass fibre filler
Copper or Stainlesssteel braided sheath
2nd Copper layer(=8.3 mm,pitch=1mm)
In-vessel pick-up coil
Ex-vessel pick-up coil
External rogowski coil
Purpose Prototype magnetics sensors
• Determine plasma current, shape and movement
• Measure thermal energy of plasma
• Detect and quantify plasma instabilities
• Reconstruct magnetic flux surfaces (equilibrium)
• Detect and quantify any current flowing from plasma into vessel
Control Protection Physics
Hall probe
28/29 October 2008Colloquium on ITER-CODAC 7
Overview of magnetics signal processing
• Around 1650 sensors in total
• Digital or analogue integrators
• Amplifiers
• Slow (4kHz) ADCs for basic equilibrium
• Fast (1 MHz) ADCs for instabilities
• Typically with optical isolation
• Data stored for specialist off-line studies
• Real-time signals distributed to other plant systems (power amplifiers for tokamak magnets, machine protection systems)
Event triggers
Off-line processing
Real-time processing
Physics studies
Control & protection
dB/dt B
dB/dt
Int
Amp
ADC
ALL NUMBERS ARE INDICATIVE
28/29 October 2008Colloquium on ITER-CODAC 8
Plasma current and shape (1/2)
• Plasma current measured by integrating magnetic field over poloidal contour (Ampere’s law)
• Plasma shape characterised by gap between plasma boundary (solid red line) and first wall
• Shape controlled by changing current in tokamak coils
28/29 October 2008Colloquium on ITER-CODAC 9
Plasma current and shape
Event triggers
ADC
Off-line processing
Real-time processing
Physics studies
Control & protection
dB/dt B
dB/dt
• Around 750 sensors (of which 380 in-vessel)
• Typical raw signal from 0.05m2 pick-up coil in +/-60mV range under normal operation; +/-5V at disruptions
• Individual signals integrated (typical time constant 100ms; output +/-5V) and digitised separately
• Integrated signal in range of 0.06Vs; frequency response ~10kHz; drift <0.35mVs after pulse of 3600s
• Summing integrator for ‘hardware’ calculation of plasma current (10kA-15MA range, 1% accuracy)
• Integrated signals typically sampled at 4kHz (20kHz at events)
• Typically 16 bit ADC with dithering, 25 bits without)
• Calibration of signals• On-line data validation checks and corrective
actions (e.g. voting system with 3 toroidal positions)
• Second plasma current calculation from individual signals
• Plasma boundary and plasma-wall gaps determined (1-2cm accuracy) 100k FLOP/cycle (10ms cycle time 0.01GFLOPS)
• Control signals generated for gap control and distributed to power amplifiers for tokamak coils
• Data stored for specialist off-line studies including full equilibrium reconstruction combining data from other diagnostics (20GB per pulse)
Int
Amp
Similar arrangement for 410 in-vessel Rogowski coils feeding vessel
current reconstruction code
ALL NUMBERS ARE INDICATIVE
28/29 October 2008Colloquium on ITER-CODAC 10
High frequency instabilities – analysis & control
• Around 270 high frequency sensors (with response up to 100kHz)
• High frequency results in relatively strong (voltage-range) signals which can be recorded directly with low gain
• Frequency response up to 300kHz
• RMS signals from summing amplifiers may for rapid overview of instabilities or for event triggering
• 16 bit resolution likely to be adequate
• Sampling rates up to 1 MHz
• Event triggering to manage data quantities
• Data stored for specialist off-line studies; of order 50GB per pulse
• Real-time signals for feedback control (resistive-wall modes)
• Additional, more specialised, event triggers
Event triggers
Off-line processing
Real-time processing
Physics studies
Control & protection
dB/dt B
dB/dt
Int
Amp
Similar arrangement for around 380 in-vessel sensors for plasma
vertical speed control; 10kHz sampling; 30GB
storage; 1GFLOPS
ADC
ALL NUMBERS ARE INDICATIVE
28/29 October 2008Colloquium on ITER-CODAC 11
Overview of requirements for some diagnostics
System Electronics ADCs Storage (per pulse)
Magnetics • 1200 integrators• 650 amplifiers
• 1600 slow ADC channels (20kHz)
• 270 fast ADC channels (1 MHz)
110GB
Bolometry • 500 lock-in amplifiers (50kHz)
• 500 ADC channels
360MB
Charge Exchange
• Read-out from up to 75 CCD cameras (100 spectra/sec. 560 pixels each)
• N/A 30GB
Core LIDAR TS
• 150 ADC channels at 20GSa/S; 10-bit samples
100MB
ALL NUMBERS ARE INDICATIVE
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