06-10-11ADAS workshop, Auburn University1 Generalised collisional-radiative modelling for Silicon and beyond Alessandra Giunta

06-10-11ADAS workshop, Auburn

University 1

Generalised collisional-radiative modellingfor Silicon and beyond

Alessandra Giunta


University 2

Introduction and motivation

In both the astrophysics and fusion domains, various studies confirm that the use of zero-density population model and truncation of the population structure at a set of low levels (even if accurate data are available for them) can lead to mis-interpretation in comparing measurements and theory.

The application to all densities and the distinguishing of metastable states, oriented to dynamic conditions, place the issue in the environment of Generalised Collisional-Radiative (GCR) model (Summers et al. 2006).

ADAS population modelling, at its highest precision, has been applied to the ions of the elements from Hydrogen up to Neon.

New analysis in the lower temperature solar chromosphere and transition region (e.g. need of Si1+) and developments in the fusion context (e.g. ITER) require the extension of the range of species up to Argon and possibly beyond.


University 3

GCR ionisation and recombination coefficients

The GCR ionisation and recombination coefficients are supplied within ADAS by the adf11 data files and are needed to provide the fractional abundances.

Main date mnemonic within ADAS

Elements Sources Comments

85 He,C,N,O,Ne,Na,Mg,Al,Si,S,Ar,Ca,Fe,Ni

Arnaud & Rothenflug (1985)

scaled in Ne

-No full GCR-No metastables-Finite density effects

89from H to Ne,

Al,Si,S,Cl,Ar,Cr,Fe,Ni,Cu,Ge,Kr,Mo,Xe

EmpiricalVan Maanen (1985)

-No full GCR-No metastables-Less accurate density correction

96

H,He,C,N,O,NeSi

Na,Mg,Al,P,S,Cl,Ar

Full GCRSummers et al.

(2006)

-Full GCR-Metastables-Finite density effects

Black: in the databaseRed: new doneBlue: new in progress


University 4

Silicon GCR work scheme

STEP 1

STEP 2

STEP 5

STEP4

STEP 3

Ionisation rates

Specific ion files

Supplemented specific ion files

Projection data

Fractional abundances

adf07

adf04

adf04 +

S & R lines

adf17

adf11


University 5

STEP 1 – Ionisation rates

adf32

adf23adf07

ADAS8#2

adf56

promotion rulesdataset

specific driverfrom promotion

rules

CADW ionisationcross-sectioncalculations

direct + excitation/autoionisationcross-sectiondataset

total ground stateionisation coefficients(ground to ground andmetastable resolved)


University 6

STEP 1 – Ionisation rates

Metastable resolved adf07

CADW calculations provide ground to ground ionisation rates.

The need of ionisation resolved into ground and metastable initial and final parents has been addressed using the semi-empirical formula of Burgess & Chidichimo (1983), which has been adjusted to the CADW calculations.

Automation is important


University 7

STEP 2 – Specific ion files

Revised adf04 for light elements

Si0+

Si1+

Si2+

Si3+

Si4+

Si5+

Si6+

Si7+

Si8+

Si9+

Si10+

Si11+

Si12+

Si13+

Cowan calculations

Dufton & Kingston (1991)

Griffin et al. (1990)

Liang et al. (2009)

Liang et al. (2009)

Witthoeft et al. (2007)

Bhatia & Landi (2003)


Bhatia & Doschek (1993)

Liang et al. (2009)


Zhang et al. (1990)

Whiteford et al. (2005)

Sampson et al. (1983)

Details for Silicon


University 8

STEP 3 – Supplemented specific ion files

adf04

adf09

adf07 ADAS807

S lines

adf08_adas807

adf18_a09_a04

ADAS211

ADAS212

RR lines

adf08

RR+DR lines

specificion dataset

ionisation rate

coefficientdataset

state selectivedielectronic

dataset

integratedmappinggenerator

radiative recombinationmapping dataset

dielectronic recombinationmapping dataset

state selectiverecombination dataset

(for archiving)

full GCR adf04

adf04 with S lines

adf04 with RR lines


University 9

STEP 4 – Projection data

adf07

adf25

adf17

ADAS407adf04

driver file for bundle-n calculation

specific iondataset

resolved ionisationrate coefficientdataset

bundle-n populationcalculation

cross-reference driver file for DR data and ls-breakdown auto-ionisation rate

adf18/a09_p204

ADAS204projection matrix


University 10

STEP 4 – Projection data

Cross-reference driver files adf18/a09_p204

oic

adf27

ADAS701

ADAS704 Supplementary Auger break-up

DR data

AUTO-STRUCTURE

driver file containing the configurations

post-processor


University 11

STEP 5 – Fractional abundances

adf11

ADAS208

projection matrix

adf18/a09_p204

ADAS404

full GCR adf04

adf10 fragment

ADAS403

adf10 iso-electronic

adf17

cross-reference driver file

low-level resolved population model

initial tabulation of GCR coefficients at z-scaled electron temperature and density

iso-electronic master file containing GCR metastable resolved coefficients

final stage to stage and

metastable resolved GCR

coefficients

ADAS405fractional

abundances


University 12

Results for Silicon – ionisation rates

Comparison with Dere (2007) – This is a zero density direct coefficient

comparison from the ground state, using the underlying CADW adf07.

CADW

Dere


University 13

Results for Silicon – recombination ratesComparison with RR+DR of Badnell (2006) - The GCR recombination

coefficients are compared with the zero density RR+DR rates of Badnell (2006). The

lowest densities used in the ratios are 103 cm

-3 for Si

+2→Si

+1 and 10

7 cm

-3 for Si

+7→Si

+6.

GCR

Badnell


University 14

Results for Silicon – fractional abundances

Comparison with Bryans et al. (2009) - The finite density

effects are more evident for low ionisation stages where the

peaks move to lower electron temperatures.

GCR (at N

e=108 cm-3)

Bryans


University 15

Beyond Silicon

Needs: ▪ Reconstructing the emission and interpreting the behaviour of elements

heavier than Ne and even Si is essential in both astrophysics (e.g. Mg, S, Fe) and fusion (e.g. Ar).

Issues: ▪ Which resolution is appropriate.

▪ Continued update of data sources in response to improved calculations (excitation, ionisation, RR, DR).

▪ Automation and precision are both essential at this stage.


University 16

Issues ▪ Resolution GCR model is implemented in ADAS as ls resolution but: - moving to medium and heavy species and more highly ionised ions ic

resolution becomes appropriate - in finite plasma, going to higher quantum shells, terms of the same nl-shells

move into relative statistical proportions, so ca resolution is adequate

- finally l-subshells of the same n-shell move into relative statistical populations and bn resolution becomes suitable.

* the model exists

◊ the model almost exists


University 17

Issues

▪ Increasing the baseline An ADAS requirement is that a baseline collisional-radiative capability is available for any elements: - raising the quality of the baseline is systematically in progress - currently a new AUTOSTRUCTURE based distorted wave excitation upgrade is in progress, with undergoing and validation checks. This will strengthen particularly excitation data from the ground and metastable levels of ions. A later upgrade will extend the distorted wave data to all transitions in the adf04 data set with R-matrix used for transitions in the ground complex. These are general baseline lifting developments and are distinct from very detailed individual ion studies.

▪ Automation - In the GCR computation procedure a number of steps were performed as ad

hoc hand manipulation (e.g. metastable fractionation). - An objective is to set up a basis for implementing all of the steps automatically

without losing the underlying precision (in progress).

Documents

06-10-11ADAS workshop, Auburn University1 Generalised collisional-radiative modelling for Silicon and beyond Alessandra Giunta