MAST Research Forum2/1-2/05

As reported by S. Kaye

MAST Goals

The goals of MAST are twofold:

- to advance key tokamak physics issues* for optimal exploitation of ITER

- to explore the long-term potential of the spherical tokamak (ST).

* e.g. as identified by ITPA (High Priority Research Areas)

Operating Schedule 2005

Operations

Engineering Break

1st PINI sourceavailable for injection intoplasma April 2005

Jan Dec

restart M5 M5bPINI #2, 28GHz ECHTAE antenna?

Jun

Jan Dec

restart M5

Jun

Option 1

Option 2

For both options a short (1 -2 week) mid-M5 break is foreseen in April/May,primarily for further diagnostic installation (e.g. edge TS, RGB cameras, DIVCAM..)

PINI #2, 28GHz ECHTAE antenna?

33kVoutage

Control room maybe upgradedduring eng. break

Modes of Operation & Planning Considerations~ 24 weeks for Physics programme in M5

Mode of operation as in M4e.g. Mon - engineering tasks, diagnostic check-out,

engineering checkout (meggering etc.) Tue (8pm)/Wed(6pm)/Thu(8pm) - operation Fri - engineering ~ 72 operational days for this regime.

Flexible, short-term (2 - 3 week), scheduling of experiments; NB. additional experimental proposals welcome during campaign.All experimental proposals to be reviewed by MEC prior to implementation.

Tremendous benefit from combining/co-ordinating experimental proposals

During PINI conditioning there will be more limited access to machine area for work on diagnostics.

ECRH operation (e.g. for start-up studies) will require one of the HV powersupplies to be switched from NBI to ECRH

Main Programme Elements in M5

Performance Optimisation Hendrik Meyer/Geoff Cunningham

Plasma Shaping & Control Graham McArdle/Geoff Cunningham

Confinement Studies Martin Valovic/Rob Akers

Transport & Turbulence Anthony Field/Rob Akers

High Beta Operation Mikhail Gryaznevich/Tim Hender

Plasma Exhaust Glenn Counsell/Andrew Kirk

Non-solenoid Start-up Alan Sykes/Mikhail Gryaznevich

NBCD Mikhail Tournianski/Rob Akers

Driver(s)

MAST priorities for 2005 (1)Performance optimisation

- H-mode optimisation (fuelling & density control, magnetic configuration, ELM/pedestal characteristics)- optimisation of high fusion gain and high bootstrap fraction regimes; formation & sustainment of ITBs

Confinement studies- expansion of database to higher power, plasma current..- dimensionless scaling (beta, A, *..)- particle confinement studies incl. pellet injection

Transport- assessment of the relative roles of electron & ion transport and the impact of micro-instabilities- investigate relationship between plasma rotation and performance

Plasma shaping & control- improve position, shape and density control capabilities- improve accuracy of equilibrium reconstruction, incorporating rotation effects and new constraints in EFIT where possible

* Studies will incorporate a counter-NBI campaign incl. QH mode studies

MAST priorities for 2005 (2)

High beta operation- progress towards development of sustained high N regimes- maximise toroidal beta and identify limitations to high beta sustainment

NBCD- assessment of NBCD efficiency & comparison with theory

Non-solenoid start-up- development of effective start-up schemes without use of central solenoid

Plasma Exhaust- ELM characteristics, link to pedestal parameters and impact on PFCs- energy distribution to first wall & divertor during transient events- SOL transport and impact of drifts on SOL flows

Collaborations & University Links

The MAST programme exploits extensive international collaborations involving most of the major fusion institutes and many universities:

- joint experiments- exchange of equipment- exchange of personnel- sharing of computer codes

The MAST Team is committed to supporting and strengthening these links.

In the experimental planning process, high priority will be given toproposals linked to such collaborative activities.

MAST/NSTX Collaboration (1)Proposed high priority areas for collaboration include:

Confinement scaling (Valovic, Akers)- expansion of low A confinement database- scaling with beta, aspect ratio (+ DIII-D)

Fuelling optimisation (Field, Maddison, Turner)- inboard fuelling- supersonic gas injection

Transport studies - TRANSP development (Akers, Muir) - GS2 simulations (Roach, Field)- ITB studies (Field)

Pedestal physics (Kirk, Meyer)- pedestal similarity studies (+ DIII-D)- pedestal structure & ELM stability (+ AUG)

ELM structure & effluxes (Kirk, Counsell)

MAST/NSTX Collaboration (2)

EBW heating, current drive & emission (Shevchenko, Volpe)- code comparison & benchmarking- emission measurements & heating studies - hardware development

Non -solenoid start-up (Sykes, Gryaznevich)

Fast particle driven instabilities (Gryaznevich, Sharapov)- e.g. beta dependence

NPA diagnostics (Tournianski, Akers)

+……………………...

Error field scaling studies (Howell, Hender)

Session GuidelinesEach session will be rapporteured by the driver(s)(BL will cover miscellaneous proposals)

Drivers will introduce their ‘thrust’ and outline the main objectives forM5 putting the aims into perspective by referring to previous work on MASTand elsewhere, if appropriate.

Drivers will ‘rapporteur’ the experimental proposals in their area.

The presentation should not consume more than 50-65% of the allotted time.

The drivers will lead the subsequent discussion of their proposed programme.

Taking into account comments & new ideas arising at the Forum, the drivers will review and revise their programmes and propose priorities. They will also lookto co-ordinate and combine their proposals with proposals in other areas and assessresource requirements. The MAST Experiments Committee will then develop the specific M5 programme.There will be some contingency to accommodate changes/new ideas during operations.

General Impressions

• Presentations well prepared, coherent– Experiments tied in well with goals

• MAST group appear to think more “outside the box” than NSTX– Many creative physics experimental proposals– NSTX group more focused on major milestones– HOWEVER, only those MAST proposals that address the key

goals, ITPA, collaborations, will survive (i.e., NSTX mindset is to pre-select which XPs will get run)

• There is a significant probability that the author of a proposal in a particular thrust will be the thrust leader

• Edge physics is the most oversubscribed thrust– All STs are similar

MAST Developments in 2005A Sykes for the MAST Team

• planned (gradual!) increase in solenoid swing

• Higher power / long pulse NBI (S PINI Spring; SW PINI end 05)

• improved c/col puff valves

• 28 GHz EBW facility (end 05)

• reversible P2 current

• testing 2 new dataq systems

• TAE antennae/coils ? (end 05)

• more and better Diagnostics….

Plasma Control

• General capability improvements P2 reversal for elongation control

Radial / Ip control improvement

Non-linear vertical feedback control

Density feedback

• Improved offline reconstruction and modelling Improvements to EFIT (incorporate rotation effects and MSE)

Zakharov approach to wall model - for EFIT and control system modelling

• New equilibrium reconstruction and control algorithms Real time optical measurement and control of plasma edge radius

Real time EFIT reconstruction and shape contro

• Scenario improvements

- Shape control at high elongation (M5/056)

- Direct induction scenario development (M5/061)

Performance Optimization - Proposals to optimise H-mode performance

M5/004: Influence of gas puff location on edge flow

M5/028: Influence of formation of diverted configuration on H-mode access.

M5/029: Influence of inner gap on H-mode access.

M5/030: Optimise ELMy H-mode performance by means of Ip ramp-up.

M5/034: High Teped stationary ELMy H-mode

M5/037: DIII-D/MAST/NSTX ELM and pedestal similarity experiments.

M5/038: L-DN (SN) ELMs and pedestal.

M5/071: Influence of torque direction on edge Er and H-mode access.

M5/076: Dependence of H-mode access on elongation and X-point height.

M5/000: AUG/MAST comparison (not yet submitted, IEA endorsed) .

Proposals towards high G incl. tolerable ELMs

M5/026: Quiescent H-mode in MAST. (external)

M5/027: Confinement and exhaust control via the magnetic configuration

M5/031: “Enhanced D” (EDA) H-mode.

M5/032: Develop MAST stationary high N H89 /q95 scenario.

M5/036: Influence of noble gas seeding on H-mode properties.

M5/054: NTM and rotation.

M5/066: Comparison of small ELM regims on MAST with C-Mod and NSTX. (external)

M5/000: Active ELM mitigation tecniques (not yet submitted)

M5/034: High Teped stationary ELMy H-mode.

Proposals towards CTF/STPP relevant regimes

M5/052: Development of high target based on #7107.

M5/055: Development of high target with QDI and MC start-up.

M5/067: Development of 2MA discharge.

M5/073: Study of flat-top limiting physics.

M5/030: Optimise ELMy H-mode performance by means of Ip ramp-up.

M5/076: Dependence of H-mode access on elongation and X-point height.

M5 Confinement proposals • M5/ 15 Ohmic Confinement Studies M4/21 AS

• 16 Expansion of MAST confinement database M4/28 mod MV

• 17 Dimensionless heat transport scalings M4/26 MV

• 13 Deuterium transport including pellets M4/20 MV

• 18 Pellet trajectory M4/27 SS

• 20 Obtaining a peaked density profile mode with pellet injection M4/33 SS

• 21 Access to high-density H-modes by pellet pre-fuelling M4/34 GM

• 23 Testing correlation of pellet deposition with rational magnetic surfaces GM

• 10 He transport M4/24 mod AP

• 22 Impurity transport in MAST M4/25 HM

• 19 Profile consistency, profile stiffness M4/38 JC

• 74 Power flow in counter-NBI heated MAST discharges RA

• 48 The influence of plasma rotation on ohmically heated ST plasmas RA

• 71 The influence of torque direction on edge Er and H-mode access RA

• 33 Confinement in counter- and co-current NBI discharges M4/22 HM

Energy

conf.

Particle

conf.

Impurity

conf.

Momentum conf

M5/74 : Power flow in counter-NBI heated MAST discharges (RA).

M5/48 : The influence of plasma rotation on ohmically heated ST plasmas (RA).

M5/71 : The influence of torque direction on edge Er and H-mode access (RA).

M5/25 : Profile consistency, profile stiffness (J.Christiansen).

On the MAST temperature profile and the influence of NBI tangency radius.

Clear overlap with transport thrust….

Transport analysis:

M5_006 R J Akers Detailed diagnosis of baseline L-mode discharge

M5_007 R J Akers Detailed diagnosis of baseline H-mode discharge

M5_008 R J Akers Detailed diagnosis of ctr-NBI L- and H-mode discharges

Transport scaling:

M5_009 R J Akers Engineering parameter scan of L- and H-mode plasmas

M5_035 H Meyer Transport comparison in co- and ctr-NBI discharges

M5_025 J P Christiansen Profile consistency, profile stiffness

Transport control:

M5_001 A R Field Co-NBI ITB studies

M5_002 A R Field Ctr-NBI ITB studies

M5_003 A R Field PEP mode studies

Rotation Studies:

M5_005 A R Field ITB formation in H-mode plasmas (NBI torque scan)

M5_045 M Nelson Toroidal and poloidal rotation studies

M5_046 M Nelson: Effect of NBI on toroidal rotation

M5_047 R J Akers: Influence of NBI power and momentum injection…

M5_048 R J Akers: Influence of rotation on Ohmic plasmas

Summary of T&T Proposals

High– thrust - Mainstream

Get right shape - Plasma Control Thrust

• elongation ~ 2.4;• elongation control during flat-top• high triangularity

• Wall model

• improved EFIT

• formation

Supporting: Deliverables:

Develop sustained high scenario - Performance Optimisation Thrust

• formation• CD• heating optimisation• H-mode limits studies

• flat-top > 0.1 s at high Ip

• demonstration of high IN

• avoidance of “soft” limits• all these at low *

Achieve and sustain high , test limits - High operation Thrust

• sustained t > 20%

• sustained N > 4

• sustained high p and high fbs

• comparison of -limits with theory• MHD studies at high

• error fields• TAE• NTM• limits studies

• Characterisation of perpendicular diffusive-like SOL transport and development of improved SOL scaling – L-mode

• Characterisation of perpendicular diffusive-like SOL transport and development of improved SOL scaling – H-mode

• Scaling of scrape-off layer turbulence vs the toroidal magnetic field, the plasma current and the plasma temperature

• Investigating time-averaged radial transport in the outer SOL• L-Mode edge turbulence BOUT comparison• SOL flows in different magnetic geometries• Impact of field and current reversal on SOL plasma flow• SOL currents due to ELMs• Spectral signatures of medium/heavy species

Edge: Scrape-off layer transport and flowsEdge: Scrape-off layer transport and flows

• Type I ELM characteristics and Impact

• ELM magnetics and dynamics

• Ergodic divertor studies

• DIIID/MAST/NSTX ELM and pedestal similarity experiments

• Divertor plasma emission at IR wavelengths

• Simple-as-possible plasma operation for code validation

• Edge Gradient Study on MAST

Plasma boundary studiesPlasma boundary studies

• Characterisation of core energy/particle losses during sawteeth

• Target power loading and radial efflux due to Sawteeth

• First wall disruption power loads

• Impact of ELMs on the "first wall”

• Characterisation of divertor power loading with multiple S-Ps

• Diagnosis of centre-column “wraiths”

• Influence of rsep on poloidal distribution of disruption

(and ELM) energy losses

• Target particle distributions during ELMs

• Divertor detachment in high density, high power plasmas

PFC power and particle loadingPFC power and particle loading

Diagnostic optimisationDiagnostic optimisation

• Effect of power loading on –ve power flux derivations from IR camera

• Divertor diagnostic comparison and validation

• Impact of target hot-spots on IR camera analysis

• Effect of ELM pulse length on target power derivation

• Commissioning of the tangentially-viewing divertor

camera system (DIVCAM)

• Commissioning of impurity flow visualization in the divertor region

• Gundestrup Probe Commissioning

• Commissioning of Second Materials Probe

Non - Solenoid Start - up

• The Merging- Compression Scheme

• The Double Null Merging Scheme

• RF start-up with O - X - B EBW CD assist

• Integrated non-solenoid start-up

M5 NBCD campaigns

• NBCD diagnosis - density scan, co-NBI(M5/011)Continue NBCD efforts started in M3/M4 using a low density, MHD free discharges. Perform a density scan at fixed, flat loop voltage with both beams set for co-injection. Diagnose plasma with all TRANSP

diagnostics in order to confirm modelling of the NBCD • Suppress/delay sawtooth activity using counter NBCD (M5/012)Suppress/delay sawtooth activity in Ohmic shot by using counter NBI. Diagnose plasma with all TRANSP diagnostics in order to confirm modelling of the NBCD.

• Investigate NBCD in strongly off axis SND (M5/014)Investigate whether the NBCD can be increased and the current profile broadened by operating in strongly off axis SND. Move plasma off midplane.

All campaigns require powerful and reliable NBI

• Ohmic: Validation of current profile evolution modelling using a known initial q-profile (M5/060)• Formation of low li off axis NBCD (M5/067)

Miscellaneous ProposalsM5/024 HELIOS Diagnostic Analysis Development & Validation

(Prof. H Summers, M. O’Mullane)M5/039 Plasma Edge Spectral Survey (400 - 680nm) (AP)M5/040 Snake & Sawteeth Analysis (GT, RJB, Prof. S Cowley)M5/041 Ar Seeding of MAST Plasmas in L and H mode for

THEMIS 1a Commissioning (Imaging Spherical CrystalSpectrometer) (MN, HM, AP, KA)

M5/050 Identification of the source of the error field (DH)M5/051 Complete the error field toroidal scaling (DH)M5/058 Investigate the effect of boundary shape on locked mode

thresholds (DH)M5/062 CXRS calibration & commissioning (NJC, MW)M5/072 CXS diagnostic development for heavy Species

(Prof. H Summers, M. O’Mullane)M5/116 Effect of non-resonant magnetic perturbations on MHD and ion

rotation plus angular momentum transport(MW, GCu, NJC)

M5/000 q profile measurement from EBW emission(FV, VS)