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ASDEX Upgrade
ASDEX Upgrade possible contribution
to extended ITPA confinement database
Ahmedabad 16 March 2016
C,. Angioni, F. Ryter and ASDEX Upgrade Team
Max-Planck-Institut
für Plasmaphysik
Max-Planck-Institut für Plasmaphysik, Garching, Germany
Global parameters capturing the impact
of toroidal rotation
Confinement DB Update
Summary of current activities and plans
S.M. Kaye for the DB working group
Introduction
AUG data to ITERDB 1998 were all from carbon wall period
Present extension:
data from C-wall after 1998
data from full W-wall until 2015 campaign
data from ITER baseline W-wall (J. Schweinzer contribution to IOS)
Extensions: higher IP and density
Ip MA ne_19 n/nGW
ITERDB 1998
Main part of extension comes from tungsten wall
Extension also includes analysis of parameters
characterizing high density operation
With increasing gas puffing, core (and pedestal top) density saturate, while
SOL density increases and pedestal top temperature decreases
Parameters can be identified to properly capture this observation
[ M. Bernert PPCF 15 ]
Analysis includes parameters to better
characterize impact of increasing density
Plasma density at the separatrix or in the SOL [already in Ryter NF 01 ]
Various definitions are possible, e.g., average density over a radial
window in the SOL, density at the separatrix or at the change of slope of
the profile around separatrix (see JET talk)
In AUG all of these show a good level of correlation, most appropriate
choice depends on charcteristic features of SOL density profile shapes in
different devices (to be compared as a function of increasing density)
Radial average betweem rho_pol = 1.01 and 1.03 seems the most
appropriate choice in AUG
Here, neSOL is the average density over 6 cm starting from the separatrix
in 10^19/m3 (practically between rho_pol = 1.0 and 1.1, ikely too large)
neSOL comes from diag LID till shot 27200, and starting from shot 26400 (with 2
-3 points for oldest shots) it is computed from ne of diag LIN
Rreliability of neSOL from diagnostic LIN will be further analysed, and might
require individual check
[ M. Bernert PhD, IPP report 2015 ]
Analysis includes parameters to better
characterize impact of increasing density
Position of separatrix can
be determined by
multiple conditions,
including
equilibrium
reconstruction,
Te = 100 eV, and
appearance of large
scatter in TS
measurements,
characteristic of SOL
dynamics
Divertor neutral pressure also increases while
core density saturates
n0div is the neutral density in the lower divertor in 10^20m-3
(signal nDivIst of diag RVE, from 20179 diag DDS. Used for FB on divertor
pressure, so regularly checked, and available on regular basis)
Not always from the same manometer, but always in the divertor region.
Available for (almost) all of the shots, not the case for neSOL, which
reguires Li beam in operation
n0div can have small differences from campaign to campaign due to
differences in calibration ( in general reliable)
Correlations between neSOL and n0div in different campaigns are being
analysed
SOL or separatrix electron density likely physically better justified and
more appropriate for multi-device comparisons than neutral pressure
Confinement behaviour at high density
delta > 0.4
Ip=0.8 MA H98 decreases rather abruptly towards high density
High triangularity points exhibit high confinement at high density
Previous studies for improved inclusion of shape used k and q95 / qcyl
[Kardaun IAEA 2006] with k^0.37 (q95/qcyl)^0.77
Confinement behaviour at high density
Ip=0.8 MA H98 decreases rather smoothly with ne_SOL
Impact of delta appears to be captured by neSOL, to be further
investigated how general this is
delta > 0.4 delta > 0.4
Confinement behaviour at high density
Ip=0.8 MA H98 decreases rather smoothly with n0div
n0div appears to order C wall and W wall less consistently than neSOL
Small set of observations to identify possible
parameters to describe effect of rotation
AUG, 1 MA, 2.5 T, q95 ~ 4, with different ratios of PRF / PTOT
RF power from ECH and ICRH [ Sommer NF 15 ]
Small set of observations to identify possible
parameters to describe effect of rotation
AUG, 1 MA, 2.5 T, q95 ~ 4, with different ratios of PRF / PTOT
RF power from ECH and ICRH
Correlations between total torque and „global“
rotation parameters
Several choices appear to be possible
Total torque is proposed as the most appropriate engineering
parameter, available from all devices and also in phases where
CXRS measurements are not available
In particular, volume averaged and central angular velocity
(analogous to existing entries of DB for density and
temperature)
Good proxy of ExB shearing rate around mid-radius can be
built as linear combination of central and volume averaged
angular velocity
• Three components in this task
– Add data closer to ITER baseline condition (+ Hybrids)
– Expand parameter range to explore hidden variables, core+pedestal scalings
– Employ advanced analysis techniques
• Data closer to ITER baseline conditions
– Include data from high-Z wall device experiments
– Status
• JET, ASDEX-U: preparing validated datasets based on discharges in IOS DB
• C-Mod to begin data preparation
• SK working with DIII-D to identify resources to do this work
• Expanded parameter range
– Estimate of neutral pressure/gas fueling/SOL density
• JET: can provide estimates of all three in principle, but… (see Romanelli)
– Multiple GIMs, each with different effects on plasma (especially MC vs DIV)
– Neutral pressure good in lower divertor, but indirect for MC: can account for
10% scatter in H98y,2
– N0_sep routinely available, but requires manual validation
• Expanded parameter range (cont’d)
• AUG:
– Average” ne_SOL best parameter for inter-device comparisons
– Analysis indicates possible relation among <ne>, ne_SOL, (see Angioni)
» Explore further, and on DIII-D, NSTX (high ) as well
– Rotation/torque
• Torque easily provided for NB-heated plasmas
• Rotation
– JET: Difficult in ILW due to reduced C-level
– AUG: Ω0, <Ω>, γE,rot (ρ=0.5) good choices
– Pedestal parameters
• No significant overlap between CORE and PEDESTAL DBs
• Provide: rped, Tped, nped, Wped
• Advanced analysis techniques (see G. Verdoolaege presentation)
• Actions
– JET, AUG to continue with data preparation and validation
– SK to work with C-Mod and DIII-D to secure their involvement
• Would like to hear from other devices as to whether discharges near the ITER baseline
condition can be contributed
– G. Verdoolaege to continue assessing sources of statistical dependences and
appropriate selection of “regressor variables”
– Plan for next teleconference in 1 to 2 months