OEDGE modeling for the planned tungsten ring experiment on DIII-D

J. D. Elder; P. C. Stangeby; T. Abrams; R. Ding; A. W. Leonard; A. G. McLean; D. L. Rudakov; E. A. Unterberg; J. G. Watkins

doi:10.1016/j.nme.2017.03.039

OEDGE modeling for the planned tungsten ring experiment on DIII-D

J. D. Elder, P. C. Stangeby, T. Abrams, R. Ding, A. W. Leonard, A. G. McLean, D. L. Rudakov, E. A. Unterberg, J. G. Watkins

Power Exhaust and Particle Control

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Abstract

The OEDGE code is used to model tungsten erosion and transport for experiments with toroidal rings of high-Z metal tiles in the DIII-D tokamak. Such modeling is needed for both experimental and diagnostic design to have estimates of the expected core and edge tungsten density and to understand the various factors contributing to the uncertainties in these calculations. OEDGE simulations are performed using the planned experimental magnetic geometries and plasma conditions typical of both L-mode and inter-ELM H-mode discharges in DIII-D. OEDGE plasma reconstruction based on specific representative discharges for similar geometries is used to determine the plasma conditions applied to tungsten plasma impurity simulations. A new model for tungsten erosion in OEDGE was developed which imports charge-state resolved carbon impurity fluxes and impact energies from a separate OEDGE run which models the carbon production, transport and deposition for the same plasma conditions as the tungsten simulations. These values are then used to calculate the gross tungsten physical sputtering due to carbon plasma impurities which is then added to any sputtering by deuterium ions; tungsten self-sputtering is also included. The code results are found to be dependent on the following factors: divertor geometry and closure, the choice of cross-field anomalous transport coefficients, divertor plasma conditions (affecting both tungsten source strength and transport), the choice of tungsten atomic physics data used in the model (in particular ionization rate for W-atoms), and the model of the carbon flux and energy used for calculating the tungsten source due to sputtering. Core tungsten density is found to be of order 10¹⁵ m⁻³ (excluding effects of any core transport barrier and with significant variability depending on the other factors mentioned) with density decaying into the scrape off layer. For the typical core density in the plasma conditions examined of 2 to 4 × 10¹⁹ m⁻³, this represents a concentration on the order of 5 × 10⁻⁵.

Original language	English
Pages (from-to)	755-761
Number of pages	7
Journal	Nuclear Materials and Energy
Volume	12
DOIs	https://doi.org/10.1016/j.nme.2017.03.039
State	Published - Aug 2017

Funding

This work was supported in part by the US Department of Energy under DE-AC05-06OR23100 b , DE-FC02-04ER54698 c , DE-AC52-07NA27344 d , DE-FG02-07ER54917 e , DE-AC05-00OR22725 f , and DE-AC04-94AL85000 g .

Funders	Funder number
US Department of Energy	DE-AC05-06OR23100 b, DE-AC04-94AL85000 g, DE-AC05-00OR22725 f, DE-FC02-04ER54698, DE-AC52-07NA27344, DE-FG02-07ER54917

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10.1016/j.nme.2017.03.039

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title = "OEDGE modeling for the planned tungsten ring experiment on DIII-D",

abstract = "The OEDGE code is used to model tungsten erosion and transport for experiments with toroidal rings of high-Z metal tiles in the DIII-D tokamak. Such modeling is needed for both experimental and diagnostic design to have estimates of the expected core and edge tungsten density and to understand the various factors contributing to the uncertainties in these calculations. OEDGE simulations are performed using the planned experimental magnetic geometries and plasma conditions typical of both L-mode and inter-ELM H-mode discharges in DIII-D. OEDGE plasma reconstruction based on specific representative discharges for similar geometries is used to determine the plasma conditions applied to tungsten plasma impurity simulations. A new model for tungsten erosion in OEDGE was developed which imports charge-state resolved carbon impurity fluxes and impact energies from a separate OEDGE run which models the carbon production, transport and deposition for the same plasma conditions as the tungsten simulations. These values are then used to calculate the gross tungsten physical sputtering due to carbon plasma impurities which is then added to any sputtering by deuterium ions; tungsten self-sputtering is also included. The code results are found to be dependent on the following factors: divertor geometry and closure, the choice of cross-field anomalous transport coefficients, divertor plasma conditions (affecting both tungsten source strength and transport), the choice of tungsten atomic physics data used in the model (in particular ionization rate for W-atoms), and the model of the carbon flux and energy used for calculating the tungsten source due to sputtering. Core tungsten density is found to be of order 1015 m−3 (excluding effects of any core transport barrier and with significant variability depending on the other factors mentioned) with density decaying into the scrape off layer. For the typical core density in the plasma conditions examined of 2 to 4 × 1019 m−3, this represents a concentration on the order of 5 × 10−5.",

author = "Elder, {J. D.} and Stangeby, {P. C.} and T. Abrams and R. Ding and Leonard, {A. W.} and McLean, {A. G.} and Rudakov, {D. L.} and Unterberg, {E. A.} and Watkins, {J. G.}",

note = "Publisher Copyright: {\textcopyright} 2017 The Authors",

year = "2017",

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doi = "10.1016/j.nme.2017.03.039",

language = "English",

volume = "12",

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T1 - OEDGE modeling for the planned tungsten ring experiment on DIII-D

AU - Elder, J. D.

AU - Stangeby, P. C.

AU - Abrams, T.

AU - Ding, R.

AU - Leonard, A. W.

AU - McLean, A. G.

AU - Rudakov, D. L.

AU - Unterberg, E. A.

AU - Watkins, J. G.

PY - 2017/8

Y1 - 2017/8

N2 - The OEDGE code is used to model tungsten erosion and transport for experiments with toroidal rings of high-Z metal tiles in the DIII-D tokamak. Such modeling is needed for both experimental and diagnostic design to have estimates of the expected core and edge tungsten density and to understand the various factors contributing to the uncertainties in these calculations. OEDGE simulations are performed using the planned experimental magnetic geometries and plasma conditions typical of both L-mode and inter-ELM H-mode discharges in DIII-D. OEDGE plasma reconstruction based on specific representative discharges for similar geometries is used to determine the plasma conditions applied to tungsten plasma impurity simulations. A new model for tungsten erosion in OEDGE was developed which imports charge-state resolved carbon impurity fluxes and impact energies from a separate OEDGE run which models the carbon production, transport and deposition for the same plasma conditions as the tungsten simulations. These values are then used to calculate the gross tungsten physical sputtering due to carbon plasma impurities which is then added to any sputtering by deuterium ions; tungsten self-sputtering is also included. The code results are found to be dependent on the following factors: divertor geometry and closure, the choice of cross-field anomalous transport coefficients, divertor plasma conditions (affecting both tungsten source strength and transport), the choice of tungsten atomic physics data used in the model (in particular ionization rate for W-atoms), and the model of the carbon flux and energy used for calculating the tungsten source due to sputtering. Core tungsten density is found to be of order 1015 m−3 (excluding effects of any core transport barrier and with significant variability depending on the other factors mentioned) with density decaying into the scrape off layer. For the typical core density in the plasma conditions examined of 2 to 4 × 1019 m−3, this represents a concentration on the order of 5 × 10−5.

AB - The OEDGE code is used to model tungsten erosion and transport for experiments with toroidal rings of high-Z metal tiles in the DIII-D tokamak. Such modeling is needed for both experimental and diagnostic design to have estimates of the expected core and edge tungsten density and to understand the various factors contributing to the uncertainties in these calculations. OEDGE simulations are performed using the planned experimental magnetic geometries and plasma conditions typical of both L-mode and inter-ELM H-mode discharges in DIII-D. OEDGE plasma reconstruction based on specific representative discharges for similar geometries is used to determine the plasma conditions applied to tungsten plasma impurity simulations. A new model for tungsten erosion in OEDGE was developed which imports charge-state resolved carbon impurity fluxes and impact energies from a separate OEDGE run which models the carbon production, transport and deposition for the same plasma conditions as the tungsten simulations. These values are then used to calculate the gross tungsten physical sputtering due to carbon plasma impurities which is then added to any sputtering by deuterium ions; tungsten self-sputtering is also included. The code results are found to be dependent on the following factors: divertor geometry and closure, the choice of cross-field anomalous transport coefficients, divertor plasma conditions (affecting both tungsten source strength and transport), the choice of tungsten atomic physics data used in the model (in particular ionization rate for W-atoms), and the model of the carbon flux and energy used for calculating the tungsten source due to sputtering. Core tungsten density is found to be of order 1015 m−3 (excluding effects of any core transport barrier and with significant variability depending on the other factors mentioned) with density decaying into the scrape off layer. For the typical core density in the plasma conditions examined of 2 to 4 × 1019 m−3, this represents a concentration on the order of 5 × 10−5.

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DO - 10.1016/j.nme.2017.03.039

M3 - Article

AN - SCOPUS:85018590584

SN - 2352-1791

VL - 12

SP - 755

EP - 761

JO - Nuclear Materials and Energy

JF - Nuclear Materials and Energy

ER -

OEDGE modeling for the planned tungsten ring experiment on DIII-D

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