08/07/05 Plasma Operations : Introduction P.J.Lomas

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Plasma Operations: General Introduction

Peter Lomas and Plasma Operations Group:-Jerzy Brzozowski, Peter de Vries, (Marco de Baar), Robert

Felton, (Emmanuel Joffrin), Isabel Nunes, Fabio Piccolo, Filippe Sartori, Luca Zabeo

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ContentsGrad Shafranov equationPoloidal coils and power suppliesPlasma ControlPlasma Equilibria, Proteus, Maxfea, EFITThe Standard equilibria, The Pulse ScheduleThe control of Toroidal FieldGas fuellingReprise

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The Grad Shafranov Equation

Force Balance

Poloidal magnetic flux function, iB R p

pBj

Poloidal current flux function, ifj Rf p

Together with Amperes Law gives

)(')()('1 2

02

02

2

ffpR

zRRRR

Key to Plasma Engineering and Tokamak data interpretation

See e.g John Wesson, Tokamaks, 2nd ed. Oxford Science Publications

Unit vector toroidal direction

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P2U

P3U

P4U

P4L

P3L

D1

D3

D4

D2

P1EU

P1C

P2L

P1EL

MSR

R S

RSMR S

For a theorist

The JET coils and iron are just the boundary conditions for solving the equation

For a Plasma EngineerThe Grad Shafranov equation is just a tool which helps us exploit the power of JET machine for producing the plasmas we want,

shape and position.

Coils, or parts of coils are arranged in circuits with the various power supplies and these are controlled by the Plasma Position and Current Control system PPCC

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Poloidal Field Circuits and Power Supplies

+ 4 Poloidal Divertor Circuits

+

-

PVFA2

PVFA4

PVFA3

+ -+

-D1

D3D4

D2

PVFA1

+

-

Shaping Circuit

P4 Circuit

P4 Imbalance Circuit

PFX

+

-PFGC

+

-

P1 External CircuitPFX Circuit

The functions of the individual circuits will be described in Plasma Ops I

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These Circuits are controlled by Shape Controller PPCC-SC using the magnetic measurements and real time boundary reconstruction

XLOC

Ip

Zp

Rp

9 PFAmplifiers

MagneticDiagnostics

other parameters

Calculate 9 PF VoltagesPPCC Decoupling

SL waveforms

IPF Protection

V

9 IPF

I

See lecture Plasma Control by Fernanda Rimini

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Grad Shafranov Solvers, Plasma Equilibrium Design Control and Reconstruction

2.0

2.0

-2.0

0.0

3.0 4.0

Region 0

Region 1

Region 2

Region 3

Region 4

Design Control Reconstruction

MAXFEA

PROTEUS

XLOC

EFIT

Physics, Mapping

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There are >69 commonly used equilibria (standard scenarios)

E.g Triangularity scan

V/SFE/LT V/SFE/HT V/SFE/VHT V/SFE/EHT ITER-LIKE

Triangularity variation 0.15-0.50 See Plasma Ops II

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Often modifications are required:-

Move outer strike

Adjust top gap

Done by editing GAP waveforms, see Plasma Control

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A particular session might require a number of different pulses, PULSE-TYPES.

These are prepared (in advance) to make up aPULSE-SCHEDULE

using the Pulse Schedule Editor XPSEDIT.

This tool gives the Session Leader control over

Toroidal FieldPoloidal Field

GasReal Time Control

You will hear a lot more about this over the week

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For example the large and complex power supplies driving the toroidal field can be driven from a single wave-form in the Pulse-Schedule Editor.

This high level control is calledLEVEL 1.

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The JET gas introduction is another complex system:-10 Gas Introduction Modules (GIMs) and one Tritium module.The plasma density needs to be processed, validated and routed the the Density Feedback and Valve controllers.

interferometer

bremsstrahlung

process

Real Time Signal

Server

GIMGIM

waveform

Dedicated pages in the pulse schedule, see Rob Felton’s talk

SL

densitywaveform

PID

RealTimeCentral

Controller

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This lecture is a very brief intoduction to:-Grad Shafranov equationPoloidal coilsPlasma ControlProtectionPlasma Equilibria, Proteus, Maxfea, EFITThe Standard equilibria, The Pulse ScheduleThe control of Toroidal FieldGas fuelling

You should now begin to understand how a JET pulse is put together.

Any questions?