Real Time Measurement and Control at JET Overview

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Real Time Measurement and Control at JETOverview
Status
Robert Felton1, and JET EFDA Contributors 1
Euratom / UKAEA Fusion Association, Culham
Science Centre, Abingdon, Oxon, OX14 3DB, UK
This work this work has been performed under the
European Fusion Development Agreement. It is
funded in part by the United Kingdom Engineering
and Physical Sciences Research Council and by
EURATOM
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JET Joint European Tokamak

• Fusion plasmas in reactor-relevant conditions
• Theory - Deuterium and Tritium easiest to access
• D D T 1MeV p 3MeV
• D T 4He 3.5 MeV n 14 MeV
• temperature 100 M oC,
• density 2-3 x 1020 m-3 (1 mg m-3)
• confinement gt 1s
• improved confinement modes
• complex interplay of magnetic and kinetic forces
• internal and edge instabilities with pressure
  gradients
• short and long range forces not classical ideal
  gas
• Practical - Toroidal Magnetic Confinement
• magnetic confinement, shape and current
• power loads on vessel components
• particle fuelling and exhaust
• impurities from plasma-wall interaction

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JET Joint European Tokamak

• Machine Engineering - many and varied issues
• vessel toroidal R 3m, r 2m, 200 m3, Inconel
• wall CFC tiles (Beryllium and Tungsten coming)
• vacuum base 10-8 mBar (cryo), plasma 10-5 mBar
• magnets 32 Toroidal, 9 Poloidal, kV, kA
• heating NB, 20MW, RF 30MHz 8MW, 3.7GHz 10MW
• fuelling 12 gas injectors pellet 500 mBarl
  per pulse
• radiological Biological shield, Tritium
  compatibility
• remote-handling radioactive and toxic (Be)
  components
• diagnostics magnetic, thermal, optical x-ray ..
  visible, neutronic ...

Pulsed 10s 300MJ
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JET Joint European Tokamak

• Systems Engineering - many and varied
• machine control
• hierarchical, distributed, pulsed
• home-grown
• real-time communications
• analogue, digital signals
• data packet networks
• operations data
• 15000 points, 35000 pulses and growing
• data acquisition
• 1ns 1s, nV .. kV,
• VME, PCI, CAMAC, PLC
• data analysis
• traditionally post pulse,
• increasingly real-time
• remote participation
• VRVS

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Tokamak Measurement Control

• Hierarchical machine control
• Systems (vessel, magnets, gas, auxiliary heat
  fuel, diagnostics)
• Independent, with common, distributed time-base
  (fibre-optic local decode)
• Controlled by specific Operators
• Connected by ethernet (TCP/UDP/IP gt 100 systems,
  miles of copper/fibre)
• Operations (experiments)
• Parameter sets designed by Session Leader in
  pulse schedule
• Distributed to the Systems by Level1 Supervisor
  infrastructure
• Checked and loaded to machine by
  Engineer-in-Charge, and System Operators
• Distributed real-time control
• Systems
• Real-time, calibrated outputs (avoid device
  dependence)
• Real-time data sent to/from a Central Controller
  over ATM AAL5 ( 40 systems)
• Central Controller has its own Operator (PDO)
• Operations
• Control algorithm - conceptualised by Scientists,
  realised by PDO
• Event driven (step NB on n2 mode) and feed-back
  (3He conc, q-profile)
• High level language in pulse schedule

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Hierarchical Machine Control

• L1 Machine Supervisors
• user interface
• component data
• parameter data
• results data
• user system logs
• L2 Machine Systems
• control status
• start stop
• set-up readout
• r-t signal processing
• r-t physics
• L3 Device Drivers
• specific functions

Level 1
Pulse
Heat
Diagnostics
Gas
Magnets
Magnets
Heat
Diagnostics
Gas
parameters
results
Level 2
RF
NB oct4
ECE
LIDAR
...
...
control
status
Level 3
laser
recorder
...
gas valve
psu
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Machine Operations
The EIC and Operators validate the parameters
(JET Operating Instructions) and load the
plant. Other users (e.g. Heating, Diagnostics)
set-up their equipment. The Plasma Duty Officer
prepares and loads Real-Time Control Algorithms.
Check Load Pulse Schedule EIC, Operators
Edit Pulse Schedule SL
Pulse Schedule
Pulse Schedule log
JET plant state
Run Pulse EIC
Pulse Schedules reference to other pulse
schedules or JET pulses convert physics
parameters to control parameters. validate
parameters for consistency and safety. non-experts
use expert scenarios for otherwise tricky
situations (shape)
JET machine
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The JET Real-Time Control Facility - Basic
Shape Current Control
Magnetics
PF Coils
Interferom Density
GAS Pellets
plasma
NBI
ICRH
LHCD
TAE
Comms network analogue
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The JET Real-Time Control Facility - 2005
Shape Current Control (PPCC)
Magnetics
VUV impurities
PF Coils
Interferom/Polarim
GAS Pellets
Vis Da, Brem, ELM
Neutron X-ray etc.
NBI
Vis H/D/T
plasma
Confinement
ECE Te (R)
ICRH
q profile
CXS Ti (R)
LHCD
Flux surfaces EQX
LIDAR NeTe(R)
TAE / EFCC
MSE pitch (R)
EQX kinetic map
Wall Load
Simulink code
Coil Protection
X-ray Ti (0)
Pale blue Diagnostic, Sky blue Analysis, Red
Heating / Fuelling / Magnets Power, Yellow
PPCC (XSC), Green RTMC
R-T Controller
R-T Signal Server
Comms network ATM, some analogue
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Distributed Process Control (Real-Time)

• Data
• physics device independent
• standard data sets
• sizes 4 to 400 float pt nos.
• rates 1 to 250 ms
• Connections
• fast, low latency lt 0.15 ms
• one-to-many
• changes local impact
• isolation fibre-optic
• range 1 .. 100 m
• Technologies
• analogue messy
• ATM AAL5 configurable, reliable, available
• Industry standard, multi-platform, multi-vendor
• Time - a seperate network

Level 2
RTControl
Magnetics
NB
Interferom
LH
q-profile
...
...
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Diagnostics Analysis
Earl FerrersMy Lords, what kind of thermometer
reads a temperature of 140 million degrees
centigrade without melting? Viscount
DavidsonMy Lords, I should think a rather
large one. from a debate on JET in the House of
Lords (1987)

• Wide range of processing techniques, and space /
  time resolution
• Filtering and down-samplingBlack Body Bolometer
  48 chan, 2ms out
• Cross-calibration factorsElectron Cyclotron
  Emission 96 chan. 2ms
• Phase tracking of modulated signals Far
  InfraRed Interferometry 15 chan. 2ms
• Lock-in amplifiers (in software) Motional Stark
  Effect 25 chan. 2ms
• Levenberg Marquadt spectral fitting Charge
  Exchange Spectr. 14 spectra, 50ms
• Thomson Scattering
• LIDAR laser 250ms, analysis 25 ms
• Plasma magnetic boundary by Taylor expansion
• XLOC 65 coeffs, 2ms
• Finite element MHD equilibrium Grad-Shafranov
• Equinox 500 pt mesh 25ms
• Interpolation Te, Ne, q, etc on flux surfaces
• Equinox map r/a 0 0.1 1.0

The JET LIDAR Thomson scattering system
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Magnets, Heating Fuelling
Physics Inputs Outputs Rate
Shape Current Magnetics PF currents 9 2
ms Vertical Stability Fast Radial Field 0.2 ms
Gas Pellets GIM3 GIM3 10 msDensity
Control Dens3 Dens3 10 ms
Neutral Beam Preq8 Pact8 10 ms120kV 60A
20 MW
Ion Cyclotron RF Preq4, dFreq4 Pact4,
dFact4 10 ms25..50 MHz 4MW
Lower Hybrid RF Preq3 Pact3 10 ms12 GHz
4MW
Alfven Eigenmode Freq Fact 10 ms
n refer to Groups flexible selection of
different NB PINIs, RF oscillators, antennae,
gasses, etc.
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The Real-Time Controller

• Preparation Level1
• User (PDO) designs and loads the algorithm
• High level process block / data flow language
• Operation Level2
• RTCC receives measurement data
• RTCC evaluates the user algorithm
• RTCC sends heat /fuel requests

Diag. Inputs
Algorithm
RTCCevaluator

• Features
• flexible, general purpose (not low-level code)
• easy (for PDO)
• Event-triggered e.g. disruption avoidance, MHD
• Feedback SISO e.g. b with NBI
• difficult (even for PDO)
• MIMO control e.g. profiles
• Vector, matrix calculations, state-space
• Modular sub-routines

Heat/FuelOutputs
Real-time 10 ms cycle
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The Real-Time Controller - Matlab/Simulink
extension

• Preparation Matlab/Simulink Level1
• User designs Matlab / Simulink models
• User generates C function, data and DLL files
• User transfers the code and parameter files to
  RTMX
• Operation Level2
• RTMX receives Diagnostic data, etc.
• RTMX sends control requests to RTCC
• RTCC relays the Heat/Fuel requests

Diag. Inputs
Simulink model
RTMX processor
RTCCevaluator

• Features
• Flexible
• EFDA users work on control problem at home lab
• Use Matlab / Simulink function libraries
  (discrete time)
• Responsibilities
• PDO still loads and runs RTMX and RTCC
• Protection stays with Local Managers

Heat/FuelOutputs
Real-time 10 ms cycle
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Control Design
E(z) error
Ufb(z) feedback
C
r(t) or R(z) reference
uff(t) or Uff(z) operating point
P
y(t) or Y(z)sensor
u(t) or U(z) actuator
System Identification To obtain signals Actuator
u(t) e.g. PNB and Sensor y(t) e.g. bN use
theoretical models TRANSP, JETTO, ASTRA, CRONOS,
GS2, or use experimental data. Model the
process P as a differential equation for y(t)
resulting from u(t). use State-Space or Laplace
transforms Y(z) GP(z) . U(z)
Control Design Design a controller C which
achieves a desired reference signal r(t) by
driving the actuator u(t) using feedback of the
measured signal y(t) within constraints (e.g.
error, settling time)Check the controller C by
simulation, using the process model P U(z)
GC(z) . E(z) E(z) R(z) - Y(z)
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RT System Engineering

• RT systems have been developed to satisfy JET
  Scientific Programme
• they work in parallel with existing measurement
  and control systems
• they integrate with existing system
  infrastructures
• Even so, diversity and sustainability not always
  balanced
• Common Application Frameworks - HTTP protocol
• 1 VxWorks, 2 Windows - healthy competition -
  should have prize-giving !
• Common Platforms
• VME PowerPC VxWorks PCI PC Windows -
  future ?
• Association-supplied Diagnostics In-kind
  procurement
• Windows Linux diverse interfaces, long-term
  support of internals ?
• RT systems will evolve further
• Need to improve functional partitioning, and data
  distribution
• Model-based system engineering not yet
  established at JET way to go!

Diagnostic
Analysis
Control
Actuator
Diagnostic
Analysis
Control
Actuator
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Work In Progress (JETs EP programme)

• Magnets / Shape and Current Control
• eXtreme Shape Control Plasma Ops, CREATE,
  ENEA, CEA
• Coil Protection System Power Supplies
• Heating and Fuelling
• xxLM upgrade to PowerPC and ATM CODAS
• RF frequency control, LH position control CODAS
• Diagnostics
• Bolometer, MSE, X-ray Expts, CODAS
• visible cameras, video distribution, hot
  spots Expts, CODAS
• Analysis
• Matlab / Simulink Plasma Ops
• Equinox and Polarimetry, MSE Plasma Ops, CEA,
  U.Nice
• Disruption Prediction Plasma Ops, U.Naples,
  ENEA
• L-mode / H-mode Plasma Ops, Murari
• Databases Communications
• extend ATM network, Plasma Ops, CODAS

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Long term To Do (JETs EP2 programme)

• Magnets / Shape and Current Control
• Vertical Stabilsation upgrade project many
  Associations, MEu !
• Error Field Correction Coils control ?
• Heating and Fuelling
• ELM info for ITER-like antenna ?
• Pellet synch
• Diagnostics Analysis
• EP2 Be / W Diagnostics, Neutron and Gamma
  Cameras
• Alven Eigenmodes ?
• RT magnetics analysis to speed up PostPulse
  Analysis
• Integrated Analysis ancient (map onto flux) and
  modern (pattern recog.)
• Databases Communications Computers
• try EPICS, MDSplus
• evaluate new network technology Is there an
  Integrated Services Data Network (control,
  status, events, audio, video, time)?
• evaluate new computer technology PCIexpress, CELL

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Summary

• Real-time Diagnostics
• simplified operation and analysis reliable
  quick-look
• real-time processing will be designed in to
  many new Diagnostics
• limited by lines of sight, field of view,
  calibration dependencies
• Real-time Magnets, Heating Fuelling
• improving modelling and control algorithms for
  shape and stability
• improving power output and control
• Real-time Experiment Control
• SISO and MIMO demonstrated more sophisticated
  tools needed
• Real-time Communications
• ATM ok - fast enough for most applications,
  flexible, reliable
• Science Requirements (JET programme in support of
  ITER) can best be satisified by Real-Time
  Measurement and Control
• Scientific Task Forces explore Plasma and Fusion
  Physics, and physics-based control concepts -
  either simple or complex
• Real-time systems are the means to practically
  demonstrate the concepts.