Atomic models and data for fusion application The ...

Atomic models and data for fusion application The ADAS Project Hugh Summers, Martin O’Mullane, Allan Whiteford, Stuart Loch*, Francisco Guzman, Adam Foster

University of Strathclyde UKAEA Culham/JET Facility * Auburn University

16 Dec. 2009 Princeton

Contents

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Some ADAS background

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Atomic modelling of ionisation state and emission in the thermal plasma.

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Atomic modelling with neutral beams

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More ADAS background and future directions

The character of ADAS

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ADAS is a reaction set database. – Comprises fundamental and derived data. – Reaction sets must be complete for a purpose, for example sufficient to support an excited population calculation for an ion. – Associated with specific diagnostic or plasma model application purposes. – The ADAS Project actively manages the procurement of fundamental data for its purposes. – It provides the tools for the preparation of applicable derived data and manages its production.

http://www.adas.ac.uk

ADAS targets

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Magnetic Confinement Fusion Plasma – Bulk plasma – Edge divertor plasma – Beam penetrated plasma

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Astrophysical Plasma – Spectral emission from the solar atmosphere – Electron excited plasmas in astrophysics

Fundamental and derived data

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The fundamental data of concern are energy levels, transition probabilities and cross-sections for relevant reactantsm of atoms and ions in plasma.

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Most spectroscopic diagnostic analysis of plasmas and most plasma models do not use fundamental reaction data directly.

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Derived data, combining the effects of perhaps many reactions through collisional-radiative models, are required, such as effective emission coefficients and effective recombination coefficients. – Plasma and atomic time constants determine the form of the derived coefficient data. – The derived data are, at minimum, functions of plasma Te and Ne.

Photon emissivity coefficient

Photon emissivities, PECs, are archived in ADAS data format adf15

C+1 Grotrian diagram

Energy levels, A-values and reaction rate coefficients are archived in ADAS data format adf04

On resolution and complexity

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From a reaction set database point of view, resolution is concerned with the fineness of the collisional-radiative modelling.

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At high resolution, use fine structure level populations with reaction data in ‘intermediate coupling’ ( ic-resolution).

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For light element ions or in zones of higher collisionality, term populations (ls-resolution), or configuration average populations (ca-resolution), even Rydberg n-shells (ryd –resolution) may be adequate.

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For light elements, H-Ne, ADAS uses collisional-radiative modelling in the generalised (GCR) form with separated highly populated metastables in lsresolution.

Rydberg representations

On top-up and projection •

Population calculations, driven by their reaction sets, are truncated.

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The infinite level atom is restricted to a finite level basis spanned by the reaction set.

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A ca reaction set may span a greater set of excited atom shells than an ls or ic reaction set, but at lower resolution.

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The database is incomplete without a capability to correct for the influence of all the higher nl- and n-shells up to infinity on truncated models.

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High Rydberg state models are simplified by the collisionality which tends to establish relative statistical populations and couples them to the free electron continuum.

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Bundling and projection give a solution.

Projection matrices are archived in ADAS data format adf17

Lifting CR models: simple top-up

Lifting CR models: propagated top-up

GCR recombination coefficients

ACD(rec)(cm3 s-1)

ACD(rec)(cm3 s-1)

10-6

10-6

O+4(2s2 1S) +e ---> O+3(2s22p 2P)

10-8

10-8

10-10

10-10

10-12

10-12

O+4(2s2p 3P) +e ---> O+3(2s22p 2P)

1012

1012 8 Ne / z17 (cm3) 10 1040.01

0.1

1

10

Te / z12 (eV)

100

8 Ne / z17 (cm3) 10 104

0.01

0.1

1

10

Te / z12 (eV)

GCR recomination and ionisation coefficients are archived in ADAS data format adf11

100

ADAS collisional-radiative data sub-classes for application

On resolution and complexity (2)

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Resolution is of great importance for heavy element ions since ic or ls resolution may easily flood computational resources.

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In ADAS, automatic preparation of reaction sets, at baseline quality, for any heavy element ion is implemented, exploiting promotion rules, optimising for available computation resources and balancing ic and ca resolution levels.

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Large numbers of weak lines form a grass-like quasi-continuum. Introduce feature emissivity coefficients (f-pec).

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Many ionisation stages cannot be handled by 2-d and 3-d transport codes.

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ADAS has introduced partitioning into superstages.

F-PEC for Hf+28 in the XUV range

Ne = 5.0 x10+13 cm-3

F-PEC data archived in ADAS data format adf40, extracted by ADAS code read_adf40.pro

W+21 default large configuration set

Automatic sizing to computer systems

The natural partition

Superstages - carbon as an illustration

C0 (2s22p2 3P)

C0 (2s22p2 1D)

Partition level #00 C+1 (2s22p 2P)

C+2 (2s2 1S)

C+4 (1s2 1S) C+3 (2s 2S)

C0 (2s22p2 1S)

C+1 (2s2p2 4P)

C+5 (1s 2S)

C+2 (2s2p 3P)

C+6 (1S)

C+4 (1s2s 3S)

C0 (2s2p3 5S)

ionisation stage -> new name “superstage” metastables -> new name “partition elements” Partition level #01

C+0

C+1

C+2

C+3

C+4

C+5

C+6

Partition level #02 C+0

C+1,C+2,C+3

C+4,C+5

C+6

Natural partition ionisation balancefor tungsten

Ionis./recom data archived in ADAS data format adf11, extracted by code ADAS405

Aggressive tungsten bundling for 2-D and 3-D divertor transport models (#02 partition)

Effective superstage recom. coefft. for tungsten #02 partition

Superstage data prepared by ADAS code ADAS416 and archived in ADAS data format adf11, adf15, adf40

ADAS collisional-radiative data sub-classes for application (2)

Charge exchange spectroscopy Partial n and partial nl CX cross-sections

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Asymptotic slope in n at higher beam energies means that cascading contributions to populating of emitting levels are significant.

Effective emission coefficients for various beam donors

CXS effective emission coefficients are archived in ADAS data format adf12

Patterns of CXS lines in the visible

On state selective charge exchange cross-section data •

Close coupled molecular orbital (CCMO), close-coupled atomic orbital (CCAO) and classical trajectory Monte Carlo (CTMC) methods are the theoretical sources for the low medium and high energy ranges of neutral hydrogen beam donors.

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Recent calculations are reinforcing the completeness of the fundamental data for light element, bare nucleus, receivers and are providing the associated donor excitation cross-sections required for beam stopping

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For argon, visible-wavelength CXS lines from Ar+18, Ar+17 and Ar+16 are measurable, localised along the beam path.

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For sub-dominant capture for charge states beyond ~ 15, CCMO and CCAO are at their computational limits. A discrepancy appears in CTMC below ~100keV/amu. This has led to an improved CTMC approach, which is under evaluation.

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As the receiver charge increases, relevant receiver states move to higher n-shells, leading to many more but weaker CXS lines. Elaborated Rydberg n- and nl- models supply the derived emission coefficient data.

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The filling of the database by CTMC calculations, currently at z~36, is allowing scaling methods to be strengthened and tentative evaluation of spectral consequences up to tungsten for ITER.

Universal scaling for heavy receiver CXS emissivities

Patterns of CXS lines in the visible (contd)

ITER: tungsten CX compared with Bremsstrahlung

• 50 keV/amu D beam (diagnostic NB), JNBI=300A/m2, INBI=60A • Using ITER scenario 2 (Te=20keV core, Ne=1x1014cm-3) • No transport – steady state ionisation balance • Assume looking vertically down on the beam at the core. • No beam attenuation effects taken into account. • W concentration = 1x10-6 of NH

Beam stopping and beam emission •

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The beam emission lines appear as Stark multiplets due to the motional electric field in the beam atom frame.

Stark manifold collisional-radiative models describe the precise wavelengths, the polar distribution and polarisation of emission and the collisional mixing for the low n-shell emission (Balmer and Paschen)

On processes and Stark-resolved beam emission spectra •

Basic ADAS beam stopping/emission models are ryd-n for H0 isotopes and ryd-nl + low level ls for He0 isotopes.

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Current activity includes improved ion impact excitation cross-section data for heavier colliders (z0 >2).

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For spectroscopy, ADAS has historically a fully resolved model, diagonalising er.vxB, μ.B and er.E perturbations explicitly for n=1-4. Recent work matches this to ryd-n modelling via projection and renormalising.

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With the fresh interest in full-feature beam emission spectroscopy, an update is in progress assessing tentative model improvements:

Tentative corrections

Stark energy levels Field ionisation

k-cascade Directional angular differential xsects.

ADAS overview and connections

http://adas.ac.uk/openadas.php http://www.adas-fusion.eu

ADAS database and computational summary •

Fundamental data, derived data, drivers etc. Currently ~ 6 Gbytes.

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There are ~ 50 different ADAS data formats.

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Some key ADF’s for general application – ADF04 : specific ion data – ADF11 : coll.-rad. ionis., recom. and related coefficients. – ADF15 : emissivity coefficients

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The pedagogical interactive user interface – ADAS series (8 series, ~85 programs).

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The application interface – ADAS Fortran and IDL subroutine libraries – Data extraction procedures and subroutines by format: xxdata_, read_adf.

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Offline-ADAS for large scale production

ADAS future planning Road map to 2013