MAST Research Forum

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MAST Research Forum 2/1-2/05
As reported by S. Kaye
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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)
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Operating Schedule 2005
PINI 2, 28GHz ECH TAE antenna?
M5
M5b
Option 1
restart
Jan
Dec
Jun
33kV outage
Operations
Control room may be upgraded during eng. break
Engineering Break
PINI 2, 28GHz ECH TAE antenna?
M5
Option 2
restart
Jan
Dec
Jun
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..)
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Modes of Operation Planning Considerations
24 weeks for Physics programme in M5
Mode of operation as in M4 e.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.
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 power supplies to be
switched from NBI to ECRH
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.
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Main Programme Elements in M5
Driver(s)
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
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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
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
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
Studies will incorporate a counter-NBI campaign
incl. QH mode studies
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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
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
Non-solenoid start-up - development of effective
start-up schemes without use of central
solenoid
NBCD - assessment of NBCD efficiency
comparison with theory
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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 to proposals linked to
such collaborative activities.
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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)
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)
Fuelling optimisation (Field, Maddison,
Turner) - inboard fuelling - supersonic gas
injection
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MAST/NSTX Collaboration (2)
Error field scaling studies (Howell, Hender)
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)
...
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Session Guidelines
Each session will be rapporteured by the
driver(s) (BL will cover miscellaneous proposals)
Drivers will introduce their thrust and outline
the main objectives for M5 putting the aims into
perspective by referring to previous work on
MAST and 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 look to co-ordinate and combine their
proposals with proposals in other areas and
assess resource requirements. The MAST
Experiments Committee will then develop the
specific M5 programme.There will be some
contingency to accommodate changes/new ideas
during operations.
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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

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MAST Developments in 2005 A 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.

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• 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)

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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) .
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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 Devel
op 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.
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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.
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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
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On the MAST temperature profile and the
influence of NBI tangency radius.
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).
Clear overlap with transport thrust.
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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
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Highb thrust - Mainstream
Deliverables
Supporting
Get right shape - Plasma Control Thrust

• elongation k 2.4
• elongation control during flat-top
• high triangularity

• Wall model
• improved EFIT
• formation

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Edge Scrape-off layer transport and flows

• 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

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Plasma boundary studies

• 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

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PFC power and particle loading

• 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 Drsep on poloidal distribution of
  disruption
• (and ELM) energy losses
• Target particle distributions during ELMs
• Divertor detachment in high density, high power
  plasmas

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Diagnostic 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

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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

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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)

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Miscellaneous Proposals
M5/024 HELIOS Diagnostic Analysis Development
Validation (Prof. H Summers, M.
OMullane) 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
Crystal Spectrometer) (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. OMullane) 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)