17 th Real-Time Conference | Lisboa, 24-28 May 2010 Plasma Control @ COMPASS a Vertical Solution H....

17th Real-Time Conference | Lisboa, 24-28 May 2010

Plasma Control @ COMPASS Plasma Control @ COMPASS a Vertical Solution a Vertical Solution

H. Fernandes, IPFN and IPP.cz CODAC team

1

Instituto de Plasmas e Fusão Nuclear - LAInstituto Superior Técnico, Lisbon, Portugalhttp://www.ipfn.ist.utl.pt

Author’s name | Place, Month xx, 2007 | Event17th Real-Time Conference | Lisbon, 24-28 May 2010 2

• Why the tokamak can hold an unstable plasma

• How is possible to ACTIVELY control this plasma

• Tools for the control– Sensors– Actuators– Control system

• COMPASS

Addressed questionAddressed question


• Two types of forces:– Radial expansion force due to the gas expansion

• (toroidal & poloidal magnetic fields can hold it)

– “Geometric” toroidal forces

• Counter-balanced by magnetic confinement– Rotational transform due to a toroidal current– Vertical field to hold horizontal displacement

• But equilibrium, once achieved, DOES NOT imply stability

EquilibriumEquilibrium


• A plasma holds a lot of free energy• If modes are available, they tend to grow,

capturing that energy• Instabilities often lead to catastrophic loss

of plasma.• How to avoid them?

– Limiting the amount of pressure or toroidal current, but high pressure is desirable

• optimize the magnetic configuration so that the pressure and current limits are as high as possible

– Using a conducting wall to increase magnetic pressure under plasma displacements

• Not feasible on large machines

StabilityStability


Need for controlNeed for control


Equilibrium and StabilityEquilibrium and Stability

• Magnetic configuration– Stable– Unstable– Marginally stable


PID controllerPID controller


DEADTIME = 1, PROPORTIONAL=.4

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CONTROLLER ITERATION

CO

NT

RO

LL

ER

OU

TP

UT I=.6

I=.8

I=.9

I=1

I=1.1

I=1.2

I=1.4

PID optimizationPID optimization

• The “proportional only” generates always an overshoot or a strong delay

• The integral term accelerates the movement towards the setpoint and eliminates the residual steady-state error

• Derivative term is used to reduce the magnitude of the overshoot produced by the integral component and improve the combined controller-process stability

DEADTIME = 2, PROPORTIONAL=.2

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CONTROLLER ITERATION

CO

NT

RO

LL

ER

OU

TP

UT I=.6

I=.8

I=.9

I=1

I=1.1

I=1.2

I=1.4


The stability problemThe stability problem

• Vertical magnetic field– Necessary for equilibrium– Can generate unstable magnetic configurations

(negative decay index)


Vertical displacementVertical displacement

Vídeo: Rui Gomes


No controlNo control


System response w/controlSystem response w/control


Induced displacementInduced displacement


• Use a macroscopic model to describe the simplified problem– Consider the plasma current as filaments– PID (engineering approach)

• Try to have a general physics model– Actively control in real-time the magnetic

topology• Very demanding on processor power

– Leading to an intrinsically stable configuration (Stellarators)

Approaches to solve the problemApproaches to solve the problem


The control systemThe control system

Tokamak:

Sensor(Magnetics)

Sensor(Interferometry)

WaveformGenerator #1

Actuator(Power Suplies)

Actuator(Gas Puffing)

WaveformGenerator #2

DATAACQUISITION

SYSTEM

“Trial-and-error” type operation

Hard to get similar discharges, as the plasma is a multivariable complex system

Reprogram of waveforms is normally an empiric and lengthy task•Data acquired needs to be correlated manually against control waveforms

Tokamak

Sensor(Magnetics)

Actuator(PSU)

Sensor(Pressure/

Interferometry)

Actuator(Gas Puffing)

Controller #1(PID)

Controller #2(PID)

Sensor XActuator Y Controller #(PID)

Single-Input Single-Output (SISO) ANALOG controllers

Not easily Re-configurable Hard to Optimize Allows only simple control

schemes (e.g PID) Control of Plasma

Parameters is NOT coupled!


Sensors & actuators @ JETSensors & actuators @ JET

Magnetics

R-T Signal Server

R-T Controller

plasma

CXS Ti (R)

MSE pitch (R)

Flux surfaces EQX

Confinement

VUV impurities

Shape & Current Control (PPCC)

ECE Te (R)

q profile

Neutron X-ray etc.

Interferom/Polarim

NBI

ICRH

LHCD

GAS + Pellets

PF Coils

Vis H/D/T

Vis Da, Brem, ELM

Comms network ATM, some analogue

X-ray Ti (0)

LIDAR Ne&Te(R)

Simulink codeEQX kinetic map

TAE / EFCC

Wall Load

Coil Protection

Rob Felton - RTMC Workshop

EP2 VS


GAS INJECTION

Gateway

Local Processing Node(ATX Motherboard/ PCIe)

WWW

Ethernet 1/10Gb Switch

Digitizer Boards

ATCA ChassisFIRESIGNAL SERVER

POWER SUPPLIES

\

Low Cost Controling Module

(dsPIC)

RS485

\

Low Cost Controling Module

(dsPIC)

RS485

POSTGRESSQL SERVER

Unified ApproachUnified Approach

• All the controllers should be able to get information from any sensor

• They should publish their decisions and operational values

• They could control several “set-points” in a MIMO design


• Compass is the first tokamak in scale towards ITER

• The adequate Scientific program

• Reasonable CODAC requirements for a full plant concept test

COMPASSCOMPASS


• Sensors• Actuators• Control Unit

System ComponentsSystem Components

• Slow control – machine operation– all systems tested and working now– Vacuum vessel conditioning

• vacuum pumping (TMP + roots + rotary)• baking up to 150oC, inductive heating

@ 452 Hz (incl. thermal management)

– Gas handling system• glow discharge• Boronization• Gas filling

– Gas puffing system

• Plasma control – fast feedback– necessary diagnostics working– simple model available– more advanced models to be applied

soon


FireSignalFireSignal

• Open Software licensing• Event and data driven• Works autonomous or as

a sub-system• Interfaces readily to other

CODACs• XML description of the

hardware• Client/Server• Nodes can be live

connected/disconnected from the system

• Uses CORBA and most SQL databases

• Remote participation and management

• Integration w/ Matlab, IDL, SciLab, C, Java, Python…


• Machine infrastructure– industrial facilities of the experiment: cooling water, power

supplies, interlock system– operation of these systems is checked and reported to CODAC

during the experiment preparation phase

• Control of slow processes in the experiment preparation phase– vacuum pumping, vessel baking, glow discharge– based on a specialized dsPIC controller board: allows handling

of several analog and digital inputs and outputs including optical serial communication lines for a PC interface.

• Slow FireSignal Node (EPICs integrated)

Machine operation - Slow controlMachine operation - Slow control


• Radial position control– Control signals from

flux loops, saddle coils, and partial Rogowski coils at mid-plane;

– Two power supplies used: the EFPS for slow control and main vertical field, and power switched amplifiers for fast control.

Plasma controlPlasma control


• Vertical position controlControlled using signals

from flux loops and partial Rogowski coils far from mid-plane (up/down asymmetry);

System uses proportional and derivative (velocity) controller;

Response is in the 200us range

Plasma controlPlasma control


System ComponentsSystem Components


• COMPASS tokamak is a test-bench for this new approaches, being the first machine completely equipped with this new standard

ATCA ChassisATCA Chassis

ATCA CRATE FRONT

ATCA CRATE BACKPLANE

ATM

ATX controller

ETHERNET

CF

CHA

JTAG

BLK1

CHB

CHC

ANALOGUE

INPUTS

BLK2

CHC

CHD

CHD

CHA

CHB

CLK

SYNC

TRG

CF

CHA

JTAG

BLK1

CHB

CHC

ANALOGUE

INPUTS

BLK2

CHC

CHD

CHD

CHA

CHB

CLK

SYNC

TRG

CF

CHA

JTAG

BLK1

CHB

CHC

ANALOGUE

INPUTS

BLK2

CHC

CHD

CHD

CHA

CHB

CLK

SYNC

TRG


ATCA™ Processor Blade

PCIeswitch

PCIeswitch

X8 4GB/s FDXX16 8GB/s FDX

12 ATCA channels(2 to 13)

X4 2GB/s FDXeach

ATCApower

ATCA Fabric channel

PCIeswitch

X16 PCIe female

connector

7-213-8

X8 4GB/s FDX

ix86Intel®

multi-core

NORTH+

SOUTHbridges

DDR2 DRAM

10 GB/s

PCIeslot

GbitEthernet

port

RS-232port

ATMAdd-on

card

X16 8GB/s FDX8GB/s8.5 GB/s

Low-Cost ATCA CPU ModuleLow-Cost ATCA CPU Module

Based on a PC plain ATX Motherboard with PCIe, assembled on a specially designed ATCA Carrier Board

Any Processor in the ix86 multi-core familyEasily upgraded to higher processing powerProcessing power over 40 GFLOPS and a set of SIMD instructionsPlain Linux or Real-time OS (RTAI)

Connected to the PCI Express™ switch fabric of the ATCA™ carrier by an ×16 full-duplex link (8 GB/s) directly from its Northbridge

Occupies 2 slots of the ATCA shelf


• 4 CPUs

• Intel Core 2 QuadTM CPU

• 1 core for linux,

• 3 cores for RT operations HS Serial connections

Processing unitProcessing unit


GAM OrganizationGAM Organization

• Generic Application Module– I/O– Data Processing– Control– Dynamic Data Storage

• Two Real-Time Threads (RTTh)– 20 kHz– 2 kHz


Jitter measurements

• Nominal jitter and interruption influence


14 I/O modules, each module: • - 32 analog inputs (18-bit @ 2 MSamples/s)• - 4 analog outputs (16-bit @ 50 MSamples/s)• - 8 digital input/output channels connected to a processor• - Xilinx Virtex-4 FPGA;• - 512 MB DDRII SDRAM;• - 11 Aurora fast serial links (for other DGP cards);• - 8 RS-485 slow serial links (external devices);• - fiber optic connector for the real-time event network;• - firmware stored on Compact Flash card.

ATCA - ADCs modulesATCA - ADCs modules


Data acquisition and real time Data acquisition and real time controlcontrol


ATCA FAST Data Acquisition ATCA FAST Data Acquisition ModuleModule

ATCA Digitizer Module 8 channel with up to 400 MSample/s@14-bit

High Power FPGA Multi-rate filtering based on events Local Control algorithms Can Implement data reduction in real-time

Developed for JET Gamma Ray Spectroscopy Enhancement Project EP2


System responseSystem response

• Magnetize Field PS • Equilibrium Field PS


• Successfully tested on:– COMPASS, – ISTTOK, – JET

• Current under test on:– ITER Fast Plant System Controller prototype

• To be used on FTU, W7-X, ITER ?

MARTe STATUSMARTe STATUS


PCM-23 Dynamic Compensation for COMPASS Tokamak Poloidal Fields

PCM-17 The COMPASS Tokamak Plasma Control Software Performance

PCM-18 EPICS as a MARTe Configuration Environment

PFE-13 Performance Comparison of EPICS IOC and MARTe in a Hard Real-Time Control Application

PFE-22 First Steps in the FTU Migration Towards a Modular and Distributed Real Time Control Architecture Based on MARTe and RTNet

PFE-4 A Survey of Recent MARTe Based Systems

Posters at RT10Posters at RT10


Acknowledgments:

This work has been carried out within the framework of the Contract of Association between the European Atomic Energy Community and "Instituto Superior Técnico" (IST).

The views and opinions expressed herein do not necessarily reflect those of the European Commission.

IST also received financial support from "Fundação para a Ciência e Tecnologia" in the frame of the Contract of Associated Laboratory.

THE ENDTHE END

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17 th Real-Time Conference | Lisboa, 24-28 May 2010 Plasma Control @ COMPASS a Vertical Solution H....

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