Post on 08-Oct-2020
C ModAlcator
−
Integrated Scenarios
ITER H-mode BaselinePresented by:
Stephen M. Wolfe
Alcator C-Mod PAC MeetingMIT Plasma Science & Fusion CenterCambridge, MAMar 2-4, 2011
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C ModAlcator
−Definitions and Scope
By “Integrated Scenarios”, we mean research aimed at reachingattractive operating points, generally cutting across multiple sciencetopics and often involving interaction and compatibility issuesbetween different plasma processes or regions
• The ITER Q = 10 DT H-mode baseline scenario features� Positive shear, q0
<∼ 1� q95 ≈ 3, βN = 1.8, HH ∼ 1, fNI ∼ 0.25, n/nG ∼ 0.85� Edge transport barrier
� BT = 5.3T,Ip = 15MA, n̄e ≈ 1× 1020m−3
• Research effort also supports aspects of the ITER “Pre-nuclear CommissioningPhase”� Operation in H and/or He majority
� Reduced parameters (≥ 12BT , Ip)
� Alternate RF Scenarios
� Issues of H-mode access, character
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 1
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C ModAlcator
−Research Focus and Orientation
Compared to the Topical Science areas, the H-mode IntegratedScenarios Research Program is more focussed on support of ITERconstruction and operations planning
• Respond to requirements identified by IO� Strong IO participation in program planning
� IO staff involvement in design, execution, analysis of experiments
• Participate in identification, definition, and execution of Joint Experiments andHigh Priority research activities of ITPA
• Proactively identify and address issues relevant to ITER planning and operation
• Address C-Mod issues of integration and scenario development impacting ourability to carry out ITER-related research
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 2
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C ModAlcator
−Addressing ITER H-mode Scenario issuesin C-Mod requires integration
Issues, Challenges are similar for C-Mod and ITER
• Divertor and wall materials and conditioning� High heat flux requirement
� Compatibility with low core radiation, Zeff
� Hydrogen isotope retention and recovery
• ICRF Heating� Challenging RF power density
� Compatibility with H-mode edge, high ne operation, ELMs
� Compatibility with wall conditioning requirements
• Control of pedestal parameters, edge relaxation� Variation of edge parameters (ν∗,β)
� Particle and impurity control
� ELM control
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 3
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C ModAlcator
−C-Mod H-mode Scenarios Research Topics
• Demonstration and validation of ITER reference scenarios� Ramp-up/Ramp-down phases
� Flattop “ITER demo” discharges
� Benchmarking of Simulation Models
• H-mode access and performance requirements
• Power handling, particle control, and impurity seeding
• Scenarios for ITER “Pre-nuclear phase”� Reduced field, current
� H, He majority operation
� IC Heating Scenarios
• Development and validation of Plasma Control strategies
• Plasma Material Interactions (addressed in Boundary section presentations)
• ELM and Pedestal Physics (see presentations on Transport and Pedestal Physics)
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 4
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C ModAlcator
−Validation of ITER reference startup C. Kessel
• Proposed ramp to 15 MA flattop in 80 sec
scales to C-Mod 1.35MA in 0.35 to 0.6 sec
(depending on 〈Te〉)• Full bore plasma with x-point formation at ∼ 1
4
maximum current needed to avoid overheating
ITER limiters
• ITER startup scenario requires low 0.7 < li < 1
for vertical stability; needs to conserve V-sec to
increase burn time
• Progress in 2010-11 experiments
� Perform density variations in rampup
? Examine effect on V-sec consumption, li, etc.
? Ohmic, ICRH, LHCD ramp-ups with similar
target n̄e
? Addresses PAC 2010 Recommendation
� Examine LH injection in rampup
? Validate ITER simulations which showed LH
has strongest impact in V-s and li of
IC/EC/LH
� Benchmarking models used for ITER simulations
ITER has determined that early diverting and large bore plasmas will be its baseline startup scenario
ITER is planning to divert at ~ 15 s in a 100 s Ip rampup
In order to simulate ITER-like discharges in C-Mod, the divert time has been reduced to 80-100 ms out of a 500 ms Ip rampup
Cleaner early plasma conditions compared to previous year
2008
2009
Time, s0.50.0
ITER must conserve volt-seconds in Ip rampup and control the current profile
C-Mod confirms V-s saving with ICRF heating in rampup
C-Mod indicates no change in li with ICRF heating, examining in TSC simulations
IT E R
C -Mod
ohm icICRF
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 5
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C ModAlcator
−Effect of density variation in ITER-likeOhmic ramp-up experiments C. Kessel
• Density range0.65 < n̄e < 1.8× 1020m−3
(0.08 < n/nG < 0.2)
• Low density is required forsignificant V-sec saving
• Increased Zeff at low,intermediate densitycompensates increased Te
• Delayed sawtooth onset,reduced li for lowest densitycase
• Uniform response oftemperature profile atbeginning of flattop
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 6
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C ModAlcator
−Initial results with LH injection in current rampshow savings of V-sec
• At Low density (n̄e∼5×1019m−3)400kW LH saves V-sec, relative toOH (or IC)
• li reduced by ∼ 10%
• Surface voltage drops promptly atLH turn-on
• Prad and Zeff are elevatedrelative to ohmic
• Effect reduced at higher n̄e
� Hard X-rays observed at alldensities
� Higher LH power may bebeneficial
� Possible relation to “densitylimit” effect (see LHpresentation)
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 7
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C ModAlcator
−Comparison of semi-empirical energy transportmodels in C-Mod ramp-up simulations C. Kessel
Theory-based models (e.g. GLF23) have
difficulty modeling L-mode, higher q95, ramp-
up phase
Compare semi-empirical models Coppi-Tang,
Bohm-gyroBohm,
Current Diffusive Ballooning Model (CDBM)
• BgB did reasonably well with Ohmic, but
predicted too high li with ICRF
• CT (with Cq = −3.5, Xmult = 2.75)
reasonable in ICRF, too low li in ohmic
• CDBM reasonable in ohmic, too high liand too peaked Te with ICRF
• Coppi-Tang with original settings based
on TFTR ohmic discharges had overly
peaked Te profiles and high li
None of these models appear to
sufficiently capture details of C-Mod
ramp-up experiments
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 8
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C ModAlcator
−C-Mod rampdown experiments address issues,constraints on ITER rampdown
• Start rampdown with EDAH-mode
• Inject ICRF power at varyinglevels, sustaining H-modes lateinto ramp
• Density tracks current (∼ constantn/nG) in ICRF heated H-mode
• Tpede also drops smoothly with
current
• H-mode avoids CS (OH1)over-current for sufficiently fastramp, at the expense of increasingli
ITER-like plasma rampdown experiments indicate that the density tracks Ip in ICRF
heated H-modesExamined 3 rampdown rates
Start rampdown with EDA H-mode
Inject ICRF power at varying levels
Sustaining H-modes thru rampdown phase
Requires ICRF powerHighly reproducible trajectories for li and nH-mode avoids OH overcurrent so long as Ip rampdown is fast enough
These results have already been used in ITER simulations
These results have already been used in ITER simulations
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 9
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−Scenario demonstrations: Full discharge sequence
• Demonstration of ITER-like equilibrium, 〈p〉, Te/Ti, power density� Control of operating point
� Benchmark transport, stability modeling
� Evaluate impurity, particle control
� Evaluate disruptivity, stability issues
• Exploration of variations about reference scenario
• Continue Validation of robust ramp-down, shut-down sequence
• Compatibility of core and boundaryInteraction with plasma-facing materials, including heat-flux and particle control,impurity seeding
• Demonstration of reliable, benign fault-handling and mitigation techniques
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 10
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C ModAlcator
−ITER Scenario Demonstration: IOS-1.1
• ITPA Joint Experiment IOS 1.1“ITER baseline at q=3, βN = 1.8,ne = 0.85nG (D, H, He)”� Some flexibility allowed in parameters
� Issues for C-Mod include ICRF at high density, stationary H-mode atq < 3.5, acheivable βN with available power
• Lower field option relieves some constraints� Relevant to pre-nuclear phase studies
� Experiments at half-field (2.7 T) (2010-11)
� Field overlap with other participating tokamaks, e.g. JET, providesgyro-size scaling opportunity
• Full-field C-Mod experiments at modest n/nG (2011-12)� Extension of demo experiments at higher and lower density in next
campaigns
� Target condition for seeding experiment IOS-1.2,Ramp-down validation IOS-2.2
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 11
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C ModAlcator
−Half field demonstration of access to ITER-like(IOS-1.1) parameters in EDA discharges C. Kessel
• Targeting q95 ∼ 3, βN>∼ 1.7,
κ ∼ 1.8,n/nG ∼ .85,H98 ∼ 1
• B = 2.7 T, use 2nd harmonic
H-minority ICRF heating scenario,
f ∼ 80 MHz
• Ip = 650kA operation (compares to
7.5MA in ITER at 2.7T (half-field))
� q95 = 3− 3.2
� βN<∼ 1.9
� H98 = 0.8− 0.95
� κ ∼ 1.75
• Some high βN discharges exhibit n=2,3
low frequency MHD (NTM?) or small
ELM activity, in addition to typical EDA
QC mode signature.
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 12
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C ModAlcator
−Near-term directions for C-Mod scenariovalidation work
• Continue development of half-field ITER-like discharge
• Develop and exploit full field (5.4 T) ITER-like discharge supporting ITPA JointExperiments
• Extend Ramp-up experiments with LHCD
• H-mode access and sustainment during current ramps (up and down)
• Continue evaluation and benchmarking of transport models to improve projectionsto ITER
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 13
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C ModAlcator
−H-mode access: Power Requirements for highconfinement H-modes A. Loarte(IO),J.Hughes, M.Reinke
• Motivation: ITER QDT = 10 H-mode Scenario
requires
� H98 ∼ 1 with Pnet/Pth ∼ 1.1− 1.4
(Pth = 0.49n0.72e B0.8S0.94)
� qdiv <10MWm−2 → Prad/Ploss ∼ 0.8
Po−div/Ploss < 0.2
• Experimental goals:
� Examine pedestal and confinement
characteristics as function of margin above
threshold power
� Evaluate margin above Pth required to reach
H∼1 in stationary conditions
� Role of core/edge radiation on power
requirement
H98∼1 achievable for sufficientPnet=Ploss−Prad−core
Low Po−div achievable with low Z seeding
Page 752nd APS Division of Plasma Physics Meeting , Chicago, Illinois, USA
� Impurity Seeding � Power scans of Pin & Pnet by scanning PICRH and impurity species/amount (N2, Ne, Ar)
�H98 ~ 1 achievable if Pnet is
high enough
�Low Po-div for lower Z seeding
Overview of Alcator C-Mod Experiments (II)
Low Z seeding � added benefits on
ICRH operation
� Fewer trips allowing high PICRH
� No increase of core Mo
S. Wukitch ���� TP9.89 (Thursday am)
0
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5
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0.0 0.3 0.6 0.9 1.2 1.5
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1.0
[MW
]
PRAD,CORE
Pin
H98
Time [sec]
[MW
]
Power to outer
divertorAr
Ne
N2
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 14
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−Power requirements for high confinementH-modes (cont)
• High confinement (H98y2 ∼ 1) achieved
for high Pnet
• Seeding allows variation of Ploss,
Prad,total
• Confinement directly correlated with Tped
consistent with picture based on core
profile stiffness
• Pnet/Pth is good ordering parameter
(roughly equivalent to net power / particle )
• Pedestal cooling at low Pnetmore
pronounced with Ar than Ne or N2, as
expected from radiation profiles
• Low Z Impurity seeding results in higher
performance H-modes
reduces incidence of high Z impurity
injections and also reduces ICRF trips
• H98,Pnet/Pth in ITER target range
obtained with low Z seeding
Page 1152nd APS Division of Plasma Physics Meeting , Chicago, Illinois, USA
� Plasma confinement directly correlated with pedestal temperature �
Universal correlation (Seeded & Unseeded H-modes)
� Higher H98 for low Z seeding associated with higher ne for same Tped
Pedestal & Confinement : Seeded H-modes
H9
8
Te,95 (eV)Te,95 (eV)
ne,9
5 (
10
20m
-3)
unseeded
Ne
Ar
N2
unseeded
Ne
Ar
N2
Page 1052nd APS Division of Plasma Physics Meeting , Chicago, Illinois, USA
Power Flow & Confinement : Seeded H-modes
� Impurity seeding allows scanning both Pin and Prad in controlled
fashion � same Pnet with different Pin and Prad,core (� Prad,total/Ploss)
� High confinement achieved for high Pnet and no overfuelling of SOL
unseeded
Ne
Ar
N2
H9
8
Pnet / Pth
ITER
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 15
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C ModAlcator
−Low divertor heat flux with low-Z seeding meetsITER spec
• Partially detached divertorconditions achieved with Ne andN2 seeding and H98∼1
• Peak q‖ reduced by over a factor 5from unseeded caseExceeds ITER requirement
• Outer divertor temperaturereduced from 1000◦C to ∼ 250◦Cwith Pnet>2MW
• H98,Po−div in ITER target rangeobtained with low-Z seeding
Page 1752nd APS Division of Plasma Physics Meeting , Chicago, Illinois, USA
� Pnet ≥ Pth (or high enough Tped) required to maintain H98 ~ 1 � ☺ ITER� If Pnet ≥ Pth � high Prad,div, low qdiv (& divertor detachment) can be achieved
with H98 = 1 by low Z seeding in C-Mod � ☺ITER� ITER QDT = 10 requirements (H98 = 1 @ Pnet/Pth ~ 1 & Po-div/Ploss < 0.2) have
been achieved by impurity seeding in H-modes ☺� optimization of
impurity mix (Ar vs. Ne, N2) may be required for highest Prad/Zeff in ITER � �
Summary and Conclusions
unseeded
Ne
Ar
N2
H98
Pnet / Pth
ITER
N2 seeded
Ne seeded
unseeded
Ar seeded
0 0.1
1.0
0.8
0.6
1.2
0.2 0.3 0.4
Po-divertor / Ploss
HIT
ER
-98
(y,2
)
ITER
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 16
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C ModAlcator
−Control of divertor power balance using radiation seeding (IOS-1.2)
• C-Mod experiments feature ITER-like divertor
power density, geometry, neutral opacity, . . .
• Extensive pedestal and divertor diagnostics
• Build on seeding results from H-mode access
experiment (2009-11)
• Optimization of Seeding, Radiative divertor control
(2010-11)
� Extend toward more ITER-like core plasma
(lower q95, . . . )
� Evaluate at higher density, investigate effect of
high edge ne
� Localization of impurity puff to minimize core
contamination, maximize divertor protection
� Dynamic comparison of recycling (Ne) and
non-recycling (N2) seed
• Develop feedback control for optimized divertor
protection, core performance (2011-12)
• Apply to ITER-like conditions 2012-13Page 1
Alcator C-mod Ideas Forum 2010 10th-12th January 2011
Optimisation of radiative H-modes & determination of mechanism for confinement deterioration at high <ne> (I)
� C-Mod has demonstrated that plasma confinement is correlated with Pnet/Pth and that
high Prad/Ploss can be achieved with H98 ~ 1 with low Z seeding
� Experiments performed at medium <ne> and midplane impurity puffing � large
average Zeff
� Discharges with high ne,edge following boronization showed poor confinement despite
large Pnet/Ploss
New experiments :
� Optimisation to achieve highest Prad/Ploss with H98 ≥ 1 & lowest Zeff to demonstrate ITER requirements (core Zeff)
� Determine mechanisms of confinement deterioration at high <ne>
Reinke PSI’10, Hughes IAEA’10, Loarte APS’10
3
• Compare the required amount of gas (N2 and Ne) required for a fiducial discharge from a number of locations 5 toroidally-spaced NINJA capillaries in the floor of
the divertor Midplane puffing Up H-port (B-port as well?) Design and install new gas tube into divertor from
midplane port • Develop feedback control of impurity seeding.
Feedback on X-point bolometer chords (ratio and absolute value) Thermoelectric currents
Experiments are needed to optimize the seeding feed loaction
NINJA capillaries
New divertor gas feed
• Experiments Before break compare H-port to B-side in terms of divertor vs core radiation (5 shots) After break
Standard fiducial 0.8-1.0 MA EDA: vary gas injection location (1 run) Use optimal location to develop feedback (1 run)
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 17
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C ModAlcator
−ITER “Pre-Nuclear” Phase (first 2-3 years)
• No deuterium operationmajority H (or He), minority He3
• Heating, CD sources undercommissioning� Ptot
<∼ 73MW (NBI, EC, IC)
� 40 < fICRF < 55MHz,PICRF ≤ 20MW
� fECRF = 170GHz,PECRF ≤ 20MW
• BT between half and full field
• CFC divertor (decision ontransition to W tbd)
Page 1Alcator C-mod Ideas Forum 2010 10th-12th January 2011
Access & exit from H-mode and H-mode characteristics versus heating deposition profile (I)
� ITER heating systems (33 MW-NNBI, 20 MW–ICRH, 20 MW-ECRH) �
conditions on development of scenarios from low Bt (2.65T) to high Bt (5.3T)
�Main issues : Shine-through for NBI, heating schemes (ICRH) and deposition location (ECRH)
� ECRH launchers designed to optimise use of ECRH in ITER (including heating of plasmas off-axis) � influence of off-axis heating on H-mode
access and performance needs to be assessed
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
BT(T)
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
0
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1
ne(1020m−3)
EC EC
IC
H minority in He
IC
3He minority
in H and He
H0
NB shinethrough
(armour, 4MW/m2
)
in H
in 4
He
q.95
= 3
ne = 0.85 nGW
ρICRH < 0.15
ρECRH < 0.5
ρECRH < 0.9
ITER Heating availability in H and He plasmas
0
5
10
15
I p(MA)
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.50
5
10
15
BT(T)
I p(MA)
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
0
0.1
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ne(1020m−3)
EC EC
IC
H minority
IC3He minority
(D and DT)
2 ωcT
(DT)
D0
NB shinethrough
(armour, 4MW/m2
)
q.95
= 3
ne = 0.85 nGW
ρICRH < 0.15
ρECRH < 0.5
ρECRH < 0.9
ITER Heating availability in D and DT plasmas
Issues:• Access to H-mode
• Ability to validate ELM mitigation technique
• Alternate RF scenarios
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 18
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C ModAlcator
−Access to ELMy H-mode in helium majorityplasmas
C-Mod experiment comparing He toD majority plasma in sameconfiguration as used for EPED-1validation study run on previous day
• Operation with majority He (some
residual D)
• Robust access to ELMy discharges at
similar power levels as in D
• Pedestal parameters also comparable to
deuterium
• H98 ∼ 1 obtained with T pede ∼ 800eV
• Results obtained over range of density,
current, power for comparison with
comparables in D, model validation
• Results favorable for prospects of
accessing ELMy H-mode in ITER
pre-nuclear phase (with sufficient power)
0 0.5 1 1.5 2-1-0.8
-0.6
-0.4
-0.2
0 Ip (MA)
0 0.5 1 1.5 20
0.5
1
1.5
2nebar(1e20/m3)
0 0.5 1 1.5 20
1
2
3
ICRF power (MW)
0 0.5 1 1.5 20
0.5
1
1.5
2
2.5 HeII monitor
0 0.5 1 1.5 20
5
10
15
20Electron betap(95) (%)
0 0.5 1 1.5 200.2
0.4
0.6
0.8
1
1.2 H ITER98y2
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 19
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−Near-term C-Mod Activities in support ofpre-nuclear phase
• Investigate L-H and H-L threshold� Species dependence of transition and confinement He (and H ?) majority
� Evaluate dependence on X-point height, equilibrium details(Pedestal/Transport Group)
� Evaluate dependence on heating profile (relevant to fixed frequency EC)(Pedestal/Transport Group)
• Characterize He majority H-modes in ITER-like configurations
• Assess relevant ICRF scenarios� He3 minority in H majority plasmas (ICRF Group)
� Consider H majority scenarios
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 20
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C ModAlcator
−Development of plasma operational controlmethods
• C-Mod & ITER PFsets have similararrangement and(multi-parameter)functionality
• Large vessel andstructure currents,especially duringstartup, ramp-down
• MIMO shape control with few actuators, minimal null space, operation nearcurrent, voltage, stress limits
• RF-based actuators for heating, non-inductive current drive
• Negligible central particle, momentum sources
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 21
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C ModAlcator
−Development and testing of plasma controlalgorithms
• Testing of plasma control strategies in relevant scenarios
� Effects of sensor noise, transient events
� Effects of currents in passive structures on control
and reconstructions
� Benchmarking of simulation codes
• Development and testing of machine protection
algorithms
� Identification of and response to sensor, actuator
faults
� Response to proximity to actuator limits
adaptive transfer to “safe shutdown sequence” or
real-time pulse “rescheduling”
� Real-time identification of proximity to plasma
instability boundaries
ITER Requires Large Gaps for Transient ControlM d li f H d t L d T iti t Q 10 ith 15 MAModeling of an H-mode to L-mode Transition at Q=10 with 15 MA
Radial inward displacement can be ≥ 10cm contact with the inner wall
Duration of inner wall contact depends on the central solenoid saturation state
Peak engineering heat loads of ~40MW/m2 Be tiles would melt in ~ 0.3 s!
PCS must maintain large enough gaps or trigger the disruption mitigation system
3J A Snipes, 2011 C-Mod Ideas Forum, MIT 10 - 12 January 2011
Need experiments & modeling to demonstrate & extrapolate control of transients
ITER Requires Large Gaps for Transient ControlM d li f H d t L d T iti t Q 10 ith 15 MAModeling of an H-mode to L-mode Transition at Q=10 with 15 MA
Radial inward displacement can be ≥ 10cm contact with the inner wall
Duration of inner wall contact depends on the central solenoid saturation state
Peak engineering heat loads of ~40MW/m2 Be tiles would melt in ~ 0.3 s!
PCS must maintain large enough gaps or trigger the disruption mitigation system
3J A Snipes, 2011 C-Mod Ideas Forum, MIT 10 - 12 January 2011
Need experiments & modeling to demonstrate & extrapolate control of transients
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 22
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C ModAlcator
−Development and testing of plasma controlalgorithms: Safe Shutdown Sequence
Example: Runaway electron discharges sometimes
encountered when running low density
• Current carried by fast (MeV) electron tail
• Large hard X-ray flux can damage sensitive
electronics
• Runaway beam can damage internal
components, blamed for some melt damage
on guard limiters
• Generally undesirable condition
Jump-ahead routine implements “soft landing”
• Senses Hard X-ray levels above threshold
during pre-set interval
• Jumps into ramp-down sequence by advancing
synchronous time counter
• In routine use during 2010-11 Experimental
Campaign
� No false positives
� 31 Successful discharge terminations
Runaway Sensing
0.0
0.5
1.0
Ip (MA)
0.0
0.6
1.2
ne (1020 m-3)
0
2
4
Hard X-rays (AU)
0 1 2t (sec)
0.0
0.5
1.0
0 1 2
Ip Program (MA)
X-ray threshold
Jump-to time
Xjump Gate 106
0307
003
106
0307
004
StandardSoft rampdown
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 23
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C ModAlcator
−Burn Control simulation experiments with ICRH1
Study evolution and stationary states of plasma with power dependent on plasmaparameters (IOS-6.3: Control of experimentally simulated burning state)
• Use ICRF minority heating tomimic centrally peaked fastion heating
• Control (part of)PICRF ∝ n2f(T ) or RDD tosimulate burn
• Apply feedback to try tomaintain constant burn poweragainst perturbations such asELMs, sawteeth, MHD,density excursions, etc
• Experiments in 2012-13
1suggested by P. Politzer (GA)
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 24
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C ModAlcator
−C-Mod H-mode Scenarios Research Program
• Program elements paced by
� ITER priorities
� C-Mod facility capabilities – Actuators, Diagnostics, Control system, Internals
• 2010-11 (since last PAC meeting):
� Approximately 9.5 run days so far (including FY10-11)
� Scenario demonstrations: Ramp-up, ramp-down; half-field scenarios
� H-mode access: Power requirements for high confinement
� Extension of impurity seeding studies
� Pre-nuclear phase: ELM characteristics in He majority plasmas
� Testing of pedestal model (see Pedestal presentation)
• 2011-12: New rotated 4-strap ICRF antenna, Improved seeding capability,
� Optimization of radiative H-modes
� ITER demos (IOS-1.1) at full field
� Extend impurity seeding (IOS-1.2) studies, develop feedback control of divertor radiation
� Evaluation of transient control requirements
� H-mode access and characteristics during current ramps
� Current rampup scenarios with LHCD
• 2012-13: Second New 4-strap ICRF antenna and automatic matching system, Additional LH launcher,DPCS enhancements
� Burn control studies
� Continue impurity seeding and power handling studies
� Development and testing of advanced plasma control/fault sensing algorithms
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 25
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C ModAlcator
−C-Mod Research on Integrated Scenarios forITER H-mode Baseline
• H-mode baseline research program addresses cross-cutting physics andtechnology issues
• Exploits ITER-relevant C-Mod parameters and tools
• Addresses High-priority ITER Research Needs
• Strongly coupled to ITPA tasks, Joint Experiments
• Many additional ITER-related experiments in Topical Science Groupsand Alternate Scenarios
Alcator C-Mod PAC Meeting Mar 2-4, 2011 smw 26