progress of the integrated plasma control working group

1J A Snipes, 7th IOS ITPA Meeting, Kyoto, Japan 18 – 21 October 2011

Progress of the Integrated Plasma Control Working Group

ITER Organization

J A Snipes


ITPA Integrated Plasma Control Working Group Mandate: The ITPA IPCWG will determine the physics requirements of the actuators and diagnostics of the ITER Plasma Control System (PCS) to permit the PCS to carry out its control functions and to meet the goals of the ITER reference scenarios

Deliverable: Produce a document for input to the PCS design describing the physics requirements of the PCS actuators and diagnostics at the conceptual design level sufficient to show their feasibility to perform the PCS functions

Timescale: Preliminary report now, intermediate report at the April 2012 IOS meeting, followed by a final report at the October 2012 IOS meeting to be in

time for the PCS CDR in November 2012

Control Area Leaders: T Casper – Pressure Profile, D Humphreys – Actuator Sharing,

A Kallenbach – Divertor Heat Flux, R La Haye - NTM, T Luce – Temperature Profile, D Mazon – Current Density Profile,

R Pitts – First Wall Heat Flux, A Polevoi – Fueling and Impurity, J A Snipes – ELM, T Tala - Rotation, D Testa – Alfvén Eigenmode Control


Integrated Plasma Control Working Group Activities

The ITPA IPCWG should provide physics input to quantify the ITER PCS requirements for actuators in time for the PCS CDR

This work should complement the work being done in the Plasma Control Group IPT and in the MHD ITPA Working Groups

• WG3: “Power requirements for ECRH & ICRF control of sawteeth”

• WG4 on “Diagnostic requirements for MHD stability control”

The IPCWG should assess the realistic feasibility of the PCS to carry out its control functions across a range of ITER scenarios

• early non-active scenarios in H/He at half and full current & field

• 15 MA, 5.3 T Q=10 inductive scenarios

• 10 – 13 MA, 5.3 T Q > 5 long pulse (1000 s) Hybrid scenarios

• 8 – 9 MA, 5.3 T Q~5 steady-state (3000 s) scenarios


What is Meant by Realistic Feasibility?

The IPCWG should take into account the actual constraints of the ITER diagnostics and actuators that will put real limits on the

control actions of the PCS

Through modeling and comparison with present experiments then determine how much those real diagnostic and actuator limitations are likely to affect the PCS control functions, such as

• NB RID thermal fatigue limits power modulation for burn control

• EC steering mirror full sweep takes 3 s + ~0.2 s to respond to PCS

The level of detail required depends on the impact a given constraint is likely to have and the amount of work required to assess it given the short timescale available before the CDR

For the CDR, only the control concept must be shown to be feasible not the detailed implementation nor the algorithms


MHD WG4 Already Did Much of the Diagnostics Task

The work was broken down into eight MHD stability or control method areas:• Stabilisation of the Vertical instability• Stabilisation of the Resistive Wall Mode (RWM) instability • Stabilisation of the Neoclassical Tearing Mode (NTM) instability• Stabilisation or modification of the Sawtooth instability• Stabilisation or modification of the Edge Localised Mode (ELM) instability• Control or modification of of the Alfvén Eigenmode (AE) instabilities• Control of the error fields leading to enhancement of instabilities• Control, prediction, avoidance or mitigation of plasma disruptive instability

Leaders, Contributors and Reviewers were nominated for each topicThe Leaders drove the process for each topic, with assistance from the ContributorsThe Reviewers reviewed the findings of the Leaders and ContributorsAn Excel spreadsheet template was used to summarise the quantifiable requirements and any unquantifiable requirements for each topic


Example of MHD WG4 Diagnostic Requirements

Leader: A. Isayama (JA-JAEA)

Contributors:O. Sauter (EU-CRPP), R. La Haye (US-GA), M. Reich (EU-AUG), E. Westerhof (EU-FOM), S. Nowak (EU-Milano)

Reviewers: Y. Gribov (IO), H .Zohm (EU-AUG), R. Buttery (US-GA), V.D. Pustovitov (RF-KRC)

Stabilisation of the Neoclassical Tearing Mode (NTM) instability


Integrated Plasma Control Working Group Progress

The IPCWG is assessing the physics requirements of the ITER PCS actuators in a similar set of spreadsheets for actuators

In addition, the IPCWG should assess diagnostic requirements in all other control areas outside MHD control as well as for

runaway electron control and mitigation

First draft spreadsheets have been produced in all of the control areas initially proposed


Fuelling and Impurity Control – 1: PelletsArea: Fueling and Impurity ControlDescription: Actuator specifications required or supplementary to control plasma fueling and both injected and sputtered impuritiesLeader: A. Polevoi (IO)Contributors: S. Maruyama (IO), E. Veshchev(IO), A.Kukushkin(IO), E.C. Skinner (US), M. Beurskens (EU), B. Stratton (US)Reviewers: J. Snipes (IO)

ActuatorPlasma parameter controlled

Availability(conditions in which it is required)

Actuator output controlled

RangeHardware dynamic limits

Hardware response time

Target area /Response time

Affected area /Response time

Affected actuators /Response time

Affecting actuators

Pellet injection

Electron density, ne and tritium density nT

DT operation if puffing is not sufficient

Source of D and T,SDT

SDT < 111 Pam3/s(up to 90%T + 10%D)

2 injectorsPellet sizes:V=92/50/33/17 mm3Frequency: 4-16 HzVariation ~ factor of 2 in 3 s

70 ms(flight in tube for 300 m/s HFS pellet).

Core/penetration to center ~ 0.2 – 4 TauE [3]

SOL/Div~ 10 ms

ELM pacing,Gas puffing,Div control,ICRH,Pumping

/All~ 10 ms

ELM pacing,Gas puffing,Div control,Pumping

/ All~ 10 ms

Pellet injectionElectron density, ne and deuterium nD

DD,DT operation if puffing is not sufficient

Source of DSD < 100Pam3/s




SOL/Div~ 10 ms


/All~ 10 ms


/ All~ 10 ms

Pellet injectionElectron density, ne and ion species nH

H,He operation if puffing is not sufficient

Source of HSH < 100Pam3/s ???




SOL/Div~ 10 ms


/All~ 10 ms


/ All~ 10 ms


Fuelling and Impurity Control – 2: Gas




RangeHardware dynamic limits

Hardware response time

Target area /Response time

Affected area /Response time

Affected actuators /Response time

Affecting actuators

Gas puffing

Electron density, ne and main ion species nH, nD, nT

For H, DD and DT operation respectively

Fluxes, SK of H2, D2, DT, T2

SUM(SK) < 200/400 Pam3/sAver/peaked (10 s)

< 1 s (63%) [2] < 1 s


SOL/Div~ 10 ms

LFS ELM pacing,Pellet fuelling,Div control,ICRH,Pumping

/All~ 10 ms

LHS ELM pacing,Pellet fuelling,Div control,Pumping,Pellet impurity/All ~ 10 ms

Gas puffing

Hydrogen minority nH, control for ICH heating(contributes to ne)

Half field operation in He, DD and DT with ICRH

H2 flux, SH

SH/SD+T>0.5% in DD, DT(mix purity),SH <200/400 Pam3/sAver/peaked (10 s)

< 1 s (63%) [2] < 1 s

Core/penetration to IC resonance (depends on IC frequency) ~ 0.2 – 4 TauE [3]

SOL/Div~ 10 ms

LFS ELM pacing,Pellet fuelling,Div control,ICRH,Pumping,Burn control

/All~ 10 ms

Sources from H-NBI, DNB, (< 0.4 Pam3/s each)ELM pacing & fuelling by H-pellets,Div control,Pumping

Gas puffingElectron density, ne and n4He density

4He phase operation

4He flux, S4He S4He < 120 Pam3/s

< 1 s (63%) [2] < 1 s


SOL/Div~ 10 ms

Div control,ICRH,Pumping

/All~ 10 ms

Div control,Pumping

/All~ 10 ms

Gas puffing

3He minority n3He, control for ICH heating(contributes to ne)

ICRH minority heating for full field operationin H,He,DD,DT

3He flux, S3He S3He < 60 Pam3/s

< 1 s (63%) [2] < 1 s

Core/penetration to IC resonance (depends on IC frequency) ~ 0.2 – 4 TauE [3]

SOL/Div~ 10 ms

Div control,ICRH,Pumping,Burn control

/All~ 10 ms

Div control,Pumping

/ All~ 10 ms


Divertor Heat Flux and Radiation Control

Actuator SensorPlasma parameter controlled


Caveats Response time


Dynamic Requirement

Impurity injection (Ar, Kr)

core foil bolometer system

Total core radiationmedium-Z impurity gas flux

possible energy confinement degrad.

50 msseparatrix power flux well above H-L threshold

Real-time total core radiated power

Impurity injection (N, Ne)

divertor foil bolometer

Total divertor radiation

low-Z impurity gas flux

core dilution 20 mshigh divertor power

Real-time divertor power

deuterium gas injection (main chamber or divertor)

pressure gauge, better: spectroscopic recombination monitor

divertor neutral pressure

D gas flux

possible confinemen degradation, load on gas plant

20 ms partial detachmentif available, recombination qualifier from Balmer line ratios


IR camera peak heat fluxlow-Z impurity gas flux

challenging for real time, core dilution

1 mshigh divertor power

real-time heat flux evaluation


divertor Te, e.g. from spectral Line ratio, probes ?

degree of recombination/detachment


Te calculation perturbed b y ELMs

20 mshighdivertor power

real time Te calculation


target currentouter divertor temperature


sensor ? 1 mshigh divertor power

Area: Detachment and target heat flux controlDescription: Actuator specifications required or supplementary to control the target heatflux and/or degree of detachmentLeader: A. Kallenbach (EU)


Rotation Profile Control



Category (MP, BC, AC)

Range Response timeTotal Latency


Flattop Requirement

NBI rotation profile NBI torque, 0-35Nm AC NBI 0-33 MW 100ms 1000msAny rotation profile

RMP coil braking rotation profile RMP coil current AC0-max coil current

10ms 500 ms

Not work very close to the neo-claasical offset rotation

If it gives a rotation change, on AUG, no rotation change observed

ICRH power, minority heating scheme

rotation profile ICRH power AC 0-20MW 10ms 1000msDepends on the ICRH heating scenario

ICRH mode conversion flow drive

rotation profile He3 concentration AC 0-20MW 10ms 500msonly when using He3 ICRH heating scenarios

only under certain He3 concentration

ECRH rotation profile ECRH power AC 0-20MW 10ms 300mspriority probably on other control with this actuator

ECRH rotation profile poloidal steering angle AC min-max 100ms 400mspriority probably on other control with this actuator

within the limit of steering the angle in real-time

Pellets rotation profile pellet frequency AC 0-6Hz 50ms 500msnot valid near Greenwald density

effect of pellet on density may restrict this

Area: Rotation Profile ControlDescription: Actuator specifications required or supplementary to control the toroidal plasma rotation radial profileLeader: T. Tala (EU)Contributors: P. Mantica (EU), D. Moreau (EU), W. Solomon (US), N. Hawkes (EU)Reviewers: J. Snipes (IO)


Current Density Profile Control




RangeResponse time

Total Latency


Dynamic Requirement

ICRH q profile Power AC 0-50 MW 250ms 250ms any timereal-time optimized power

NBI q profilePower (Beam modulation algorithm)

AC 0-20 MW 500ms 500ms any timereal-time optimized power

EC system q profilePower (Gyrotron modulation algorithm)

AC 0-20 MW 250ms 250ms any timereal-time optimized power

EC system q profile Miror angle AC 0-max 250ms 250ms any timereal-time optimized miror angle

Loop Voltage q profilePrimary coil current

AC 0-40 kAt 500ms 500ms any timereal-time optimized coil current

LH q profile Power AC 0-20 250ms 250ms any timereal-time optimized power

LH q profilerefractive parallel index

AC 1,8-2,2 250ms 250ms any timereal-time optimized refractive index

Area: Current Density Profile ControlDescription: Actuator specifications required or supplementary to control the plasma current density profileLeader: D. Mazon (EU)Contributors: D. Moreau (EU), N. Hawkes (EU)


Temperature Profile Control




RangeResponse time

Total Latency


Flattop Requirement

Dynamic Requirement

Notes

EC system (off-axis), NB or IC system (on-axis)

Temperature profile

Aiming angles (EC), total power output (all)

EC aiming (full range), Total power (0-max)

1-5 s Current rise phase (all scenarios)

Real-time optimized waveforms

[1]

EC system (off-axis), NB or IC system (on-axis)

Temperature profile

Aiming angles (EC), total power output (all)

EC aiming (full range), Total power (0-max)

1-5 s Baseline scenario

50 MW total power

Maintain burn or target stored energy

[2], [3]

EC system Parallel currentAiming angles, power

Full range 1-5 s Steady state scenario

Must maintain burn and total non-inductive current drive

[4]

IC systemPlasma rotation (poloidal?)

Power, frequency Full range 1-5 s All scenarios, but primarily steady state

Must maintain burn and total non-inductive current drive

[5]

Notes Expanded Details[1] Need feed-forward and feedback control in the current rise, especially for advanced scenarios[2] Looking for changes to the parallel conductivity profile to avoid tearing modes[3] Heating profile will have weak response in Q=10 plasma due to strong central heating from alphas

[4]Speculative scheme for steady state uses strong temperature profile response to reversed shear to meet Q=5 steady state goal. Must control reversal point.

[5] Speculative scheme for confinement uses driven poloidal flows by ICRF to alter the energy transport locally

Area: Temperature Profile ControlDescription: Actuator specifications required or supplementary to control the amplitude and frequency of ELMsLeader: T.C. Luce (1st draft writer)Contributors: J. A. Snipes (IO)


Pressure Profile Control


Actuator output controlled Response timeAvailability(conditions in which it is required)

Notes

ECH Te,Ne power and antenna aiming >.5s all scenarios [1],[2],[3]

NBI Te, Ti, momentumpower at a given beam aiming

> .5s all scenarios [1],[2],[4]

ICH Te, Ti spectrum >.5s steady-state [1],[2],[4]

pellet ne size and rate of pellets few Hz all scenarios [1],[2]

current density control J or q to alter transport see current density hybrid and steady-state

[1],[2],[4],[5]

rotation controlmomentum to alter transport

see momentum hybrid and steady-state

[1],[2],[4],[6]

fueling control ne see fueling&impurtiy all scenarios [1],[2],[7]

temperature control Te,Ti see Temperature all scenarios [1],[2],[8]

Area: Pressure Profile Control

Description:Actuator specifications required or supplementary to control the plasma pressure profile, plasma stored energy, and fusion burn

Leader: T. Casper (IO)Contributors: D. Moreau (EU), M. Beurskens (EU), N. Hawkes (EU)


ELM Control




RangeTotal Response time

Total Latency


Flattop Requirement

Dynamic Requirement

Pellet injection ELM frequency Pellet size MP1-4×10^21 D particles

20 ms

10-30% inter-ELM period

Ip > 6 - 9 MA

Minimal fueling

Real-time optimized pellet size

Pellet injection ELM frequencyPellet repetition rate

MP 30 - 60 Hz 20 ms


Ip > 6 - 9 MA

DW_ELM < 0.7 MJ

Real-time optimized repetition rate

Pellet injection ELM amplitude Pellet velocity MP1-4×10^21 D particles

20 ms


Ip > 6 - 9 MA

300 - 500 m/s

Real-time optimized pellet size & speed

Resonant Magnetic Perturbation

ELM amplitude ELM coil current MP0-90 kAt peak

150 ms 100 msIp > 6 - 9 MA

90 kAt peak 5 Hz rotation

VS in-vessel coils

Vertical position jogs

VS coil current MP0-40 kAt RMS

150 ms 100 msIp > 6 - 9 MA

T_coil < 160 °C

6 cm, 50 Hz

EC system ELM amplitude EC power MP 0-7 MW 150 ms 100 msIp > 6 - 9 MA

Area: ELM ControlDescription: Actuator specifications required or supplementary to control the amplitude and frequency of ELMsLeader: J. A. Snipes (IO)Contributors: A. Loarte (IO), Y. Gribov (IO), J. Lister (EU)


NTM Control




RangeResponse time

Total Latency


Flattop Requirement

Dynamic Requirement

ECCDm=2,n=1 Mirnov amplitude

Mirror poloidal position

BCplus or minus one degree

three degrees per sec

no more than 24 msec (0.1 sweep time)

Ip>6-9 MA

Mirnov amplitude less than 5G (w=1.4 cm)

Find and set alignment by "target lock"

ECCDm=2,n=1 Mirnov amplitude

EC power BC 3-6 MW



Ip>6-9 MASufficient EC power pulsed on

Find and set alignment by "target lock"

ECCDAlignment of ECCD on q=2

Mirror poloidal position

BCplus or minus 0.5 degrees

three degrees per sec

no more than 30 msec (time to 1.4 cm wo ECCD)

Ip>6-9 MAAlign to 0.5 cm or less

Measure q=2 and ECCD locations

ECCDAlignment of ECCD on q=2

EC power BC >3.5 MW CW_________

Ip>6-9 MASufficient EC power maintained

______________

Area: Neoclassical Tearing Mode ControlDescription: Actuator specifications required or supplementary to control classical and neoclassical tearing modesLeader: R. La Haye (US)Contributors: R. Buttery (US), O. Sauter (EU)


Alfvén Eigenmode Control




RangeResponse time

Total Latency


Flattop Requirement

Dynamic Requirement

Notes

active coils (such as RMP coils with high frequency capabilities)

BetaPrimeAlpha (= radial gradient of the alpha particle pressure profile)

current and voltage of active coils

AC

I_coil: up to ~50A-peak (AC)V_coil: up to ~3kV-peak (AC)frequency: ~50kHz to ~300kHz

under ~10ms + RF shielding effect of blanket modules

2ms to 5ms + RF shielding effect of blanket modules

(1) all DT shots(2) should be tested on non-DT shots with NBI/ICRF fast ions replacing alphas

control over flat-top should not be needed if discharge scenario is setup to avoid high amplitude AEs

d(I_coil)/dt~50A/msec (value will be limited by voltage rise on active coils and coils' self inductance)

need capability for reliable real-time measurement for advanced control. (see "Notes" below for further details).

plasma shaping coils


current and voltage of plasma shaping coils

AC

asking for <5% variation in edge elongation, should be within present capabilities of plasma shpaing coils (as currently in JET)

under ~10ms + RF shielding effect of blanket modules

2ms to 5ms + RF shielding effect of blanket modules



need <5% variation in edge elongation within 10ms, should be well within present capabilities of plasma shaping coils (as in JET)


ECCD system


ECCD power and injection angles

ACdifficult to estimate, would require detailed modelling

under ~50ms

10ms to 25ms



difficult to estimate, would require detailed modelling


Area: Alfvén Eigenmode ControlDescription: Actuator specifications required or supplementary to control the effects of Alfvén eigenmodes on fast ion transportLeader: D. Testa (EU)Contributors: A. Fasoli (EU)Reviewers: J. Snipes (IO)


Shared Actuators: Leader – Dave Humphreys

Actuator

Plasma/machine characteristics, parameters controlled1

Intermediate control/sensed variables

Actuator outputs controlled

Shared Actuators3 Type of Sharing2


RangeRepurposing Time

Flattop (Scenario) Requirements

Dynamic Requirements

Notes

PF power supplies

Equilibrium shape + divertor/strikept geometry + Ip + li + (vertical stability)4 + (RE control)

Gap distances, strikept locations, vertical position

PF PS currents PF PS SMM MP, BC N/A ???

Robustness dynamic requirements still not analyzed? Possibly will increase demand on PF PS (esp. req on stkpt accuracy with disturbances)

PF circuitEquilibrium control -> RE control

Gaps -> RE position/current

PF PS currentsPF PS -> BD resistors?

RP MP? 100 ms N/A100 ms RP time

Scenario: repurpose PF's from gap control to RE position/current control (possibly including re-switch in of BD resistors to extract current from divertor coils to drop decay index)

VS3 power supply

Vertical stability + divertor heating

Vertical velocity (position), ELM frequency

VS3 PS voltage/current

N/A RP (SMM?) MP, BC 0-240 kAt 5 ms ??? 5 ms RP time

VS control + Vertical jog oscillation SMM, assume same peak current requirement, but RP requirment comes from need to detect and repurpose for full amplitude VDE suppression

EC launcher mirrors

m/n=2/1 island amplitude + current profile characteristics + sawtooth stability

ECCD alignment with island, location of deposition

Launcher mirror poloidal angles, injected power, modulation frequency

Midplane launchers, NBI

RP BC/AC5

plus/minus 20 degrees? 0-9 MW?

100 ms ???6-10 deg/sec unidirectional slew rate?

Scenario: Repurpose from profile control + sawtooth suppression to 2/1 NTM suppression (requires more time to RP and align)

EC launcher mirrors

m/n=2/1 island amplitude + current profile characteristics + sawtooth stability

ECCD alignment with island, location of deposition

Launcher mirror poloidal angles, injected power, modulation frequency

Midplane launchers, NBI

SMM BC/AC

plus/minus 20 degrees? 0-12 MW?

Higher peak power?

Alignment accuracy +/- 0.5 cm? (if no higher peak power)

Scenario: SMM, assume 1/2 power to profile control/sawtooth control, 1/2 power to NTM suppression (requires faster and higher accuracy alignment?)

Pellet launchers

Fueling + ELM pacing +Disr Mitig + RE damping

Density, ELM freq,, relative stability, RE current

Launcher triggers

multiple pellet launchers

RP (SMM?) BC ??? ???Scenario: repurpose from Flattop operation to disruption mitigation /control mission

RMP coils

ELM control + EFC + LM rotation + RE deconfinement

ELM amplitude, NTM amplitude/ rot. Frequency

RMP coil PS currents

N/A SMM BC0-120 kAt peak

Speculate need additional 30 kAt for EF correct, LM rotation

RMP coils

ELM control + EFC + LM rotation +( RE deconfinement)

ELM amplitude, NTM amplitude/ rot. Frequency -> RE current

RMP coil PS currents

N/A RP BC0-120 kAt peak

Scenario: Repurpose from flattop SMM's to deconfinement of RE

MGIDisruption mitigation + (RE damping)

RE currentimpurity gas flow timing, (rate)

multiple gas species, gas valve, rupture disk

RP, SMM MP0-10000 torr-liter? Ne/He?

Scenario: repurpose from initial disruption mitigation to post-TQ RE damping (or SMM action prior to TQ?)


What Should the Final IPCWG Document Contain?

The document produced by the IPCWG should state what are the minimum actuator and diagnostic requirements that are necessary for the PCS to control ITER plasmas for the non-active, inductive, Hybrid, and steady-state DT scenarios concentrating particularly on H&CD profile control, fueling, and impurity control

It should also compare those necessary requirements with actuator and diagnostic requirements and limitations as specified in the

ITER baseline documents (Project Requirements, SRD’s, etc)

It should point out any discrepancies that are likely to compromise any of the PCS control functions for any of these scenarios

Suggestions should then be proposed that could either recover the PCS control function in question or propose an R&D plan to try to find a way to resolve the issue


IAEA Technical Meeting on Plasma Control

Paper presented on Actuator and Diagnostic Requirements of the ITER PCS at the IAEA TM on Plasma Control, June 2011

Submitted for publication to Fusion Engineering and Design

This paper covered the main actuator and diagnostic requirements of the PCS that have been studied to date including:

• Magnetic control requirements

• Specific limitations of the H&CD and fueling and pumping systems

• A summary of the MHD control diagnostic requirements assessed by the MHD ITPA WG4

• A summary of the WG3 sawtooth control requirements


Need to Include all Control Areas

The PCS CDR must cover all control areas expected for ITER operation in inductive, Hybrid, and steady-state scenarios

To complete the PCS control areas, additional leaders have been nominated for the remaining PCS control topics:

Control Area Leader

Axisymmetric Magnetic Control L Zabeo (IO)

Error Field Control M Schaffer, S Sabbagh (US)

RWM Control S Sabbagh (US)

Disruption and Runaway Control and Mitigation S Putvinski (IO)

Sawtooth Control I Chapman (EU)

Wall Conditioning M Shimada (IO)

Anyone else who would also like to contribute to this effort in any control areas, please send me their name and area

progress of the integrated plasma control working group

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