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

Overview of database extension, H98 vs density

ITER base line (W-wall)

+ W-wall

o C-wall

Overview of database extension, neSOL, n0Div

ITER base line (W-wall)

+ W-wall

o C-wall

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

Core density saturates towards high density while

ne_SOL and divertor neutral pressure increase

Impact of delta in C- wall, additional plots

Impact of delta in W- wall, additional plots

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

Correlations between total torque and „global“

rotation parameters

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

H-mode Database Update Update

S.M. Kaye for the DB Working

Group

16 March 2016

• 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