Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
Book Description
A summary is given of the work carried out under the LDRD project 09-ERD-025 entitled Scrape-Off-Layer Flow Studies in Tokamaks. This project has lead to implementation of the new prototype Fourier Transform Spectrometer edge plasma flow diagnostic on the DIII-D National Fusion Facility at General Atomics, acquisition of carbon impurity concentration and flow data, and demonstration that the resulting data compare reasonably well with LLNL's edge plasma transport code UEDGE. Details of the work are contained in attached published papers, while the most recent results that are being written-up for publication are summarized in the report. Boundary plasma flows in tokamak fusion devices are key in determining the distribution of fuel and impurity ions, with tritium build-up in the walls an especially critical operational issue. The intrusion of impurity ions to the hot plasma core region can result in serious energy-loss owing to line radiation. However, flow diagnostic capability has been severely limited in fusion-relevant hot edge plasmas where Langmuir-type probes cannot withstand the high heat flux and traditional Doppler spectroscopy has limited resolution and signal strength. Thus, new edge plasma flow diagnostic capabilities need to be developed that can be used in existing and future devices such as ITER. The understanding of such flows requires simulation with 2-dimensional transport codes owing to the geometrical complexity of the edge region in contact with material surfaces and the large number of interaction physical processes including plasma flow along and across the magnetic field, and coupling between impurity and neutral species. The characteristics of edge plasma flows are substantially affected by cross-magnetic-field drifts (ExB/B2 and BxVB/B2), which are known to introduce substantial convergence difficulty for some cases. It is important that these difficulties be overcome so that drifts can be included in transport models, both for validation with existing data and for projection to future devices.
Scrape-Off-Layer Flow Studies in Tokamaks
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
Book Description
A summary is given of the work carried out under the LDRD project 09-ERD-025 entitled Scrape-Off-Layer Flow Studies in Tokamaks. This project has lead to implementation of the new prototype Fourier Transform Spectrometer edge plasma flow diagnostic on the DIII-D National Fusion Facility at General Atomics, acquisition of carbon impurity concentration and flow data, and demonstration that the resulting data compare reasonably well with LLNL's edge plasma transport code UEDGE. Details of the work are contained in attached published papers, while the most recent results that are being written-up for publication are summarized in the report. Boundary plasma flows in tokamak fusion devices are key in determining the distribution of fuel and impurity ions, with tritium build-up in the walls an especially critical operational issue. The intrusion of impurity ions to the hot plasma core region can result in serious energy-loss owing to line radiation. However, flow diagnostic capability has been severely limited in fusion-relevant hot edge plasmas where Langmuir-type probes cannot withstand the high heat flux and traditional Doppler spectroscopy has limited resolution and signal strength. Thus, new edge plasma flow diagnostic capabilities need to be developed that can be used in existing and future devices such as ITER. The understanding of such flows requires simulation with 2-dimensional transport codes owing to the geometrical complexity of the edge region in contact with material surfaces and the large number of interaction physical processes including plasma flow along and across the magnetic field, and coupling between impurity and neutral species. The characteristics of edge plasma flows are substantially affected by cross-magnetic-field drifts (ExB/B2 and BxVB/B2), which are known to introduce substantial convergence difficulty for some cases. It is important that these difficulties be overcome so that drifts can be included in transport models, both for validation with existing data and for projection to future devices.
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
Book Description
A summary is given of the work carried out under the LDRD project 09-ERD-025 entitled Scrape-Off-Layer Flow Studies in Tokamaks. This project has lead to implementation of the new prototype Fourier Transform Spectrometer edge plasma flow diagnostic on the DIII-D National Fusion Facility at General Atomics, acquisition of carbon impurity concentration and flow data, and demonstration that the resulting data compare reasonably well with LLNL's edge plasma transport code UEDGE. Details of the work are contained in attached published papers, while the most recent results that are being written-up for publication are summarized in the report. Boundary plasma flows in tokamak fusion devices are key in determining the distribution of fuel and impurity ions, with tritium build-up in the walls an especially critical operational issue. The intrusion of impurity ions to the hot plasma core region can result in serious energy-loss owing to line radiation. However, flow diagnostic capability has been severely limited in fusion-relevant hot edge plasmas where Langmuir-type probes cannot withstand the high heat flux and traditional Doppler spectroscopy has limited resolution and signal strength. Thus, new edge plasma flow diagnostic capabilities need to be developed that can be used in existing and future devices such as ITER. The understanding of such flows requires simulation with 2-dimensional transport codes owing to the geometrical complexity of the edge region in contact with material surfaces and the large number of interaction physical processes including plasma flow along and across the magnetic field, and coupling between impurity and neutral species. The characteristics of edge plasma flows are substantially affected by cross-magnetic-field drifts (ExB/B2 and BxVB/B2), which are known to introduce substantial convergence difficulty for some cases. It is important that these difficulties be overcome so that drifts can be included in transport models, both for validation with existing data and for projection to future devices.
Modeling and Analysis of the DIII-D Tokamak Scrape-off Layer and Divertor
Author: Quang Thanh Nguyen
Publisher:
ISBN:
Category :
Languages : en
Pages : 238
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 238
Book Description
Modelling of the impurity flow in the tokamak scrape-off layer
Author:
Publisher:
ISBN:
Category :
Languages : de
Pages : 27
Book Description
Publisher:
ISBN:
Category :
Languages : de
Pages : 27
Book Description
Scrape-off Layer Flows, Magnetic Topology and Influence on the L-H Threshold in a Tokamak
Author: Brian LaBombard
Publisher:
ISBN:
Category :
Languages : en
Pages : 24
Book Description
The dependence of L-H power threshold on magnetic topology (upper-, lower-null) in a tokamak is linked to near-sonic plasma flows in the high-field side scrape-off layer. Scrape-off layer flow momentum, coupling across the separatrix, imparts a topology-dependent increment to edge and core toroidal rotation (counter-, co-current). In all topologies, rotation increases in the co-current direction with input power: the L-H transition is seen when co-rotation achieves a characteristic level. Correspondingly, higher power is required to attain H-modes in upper- versus lower-null (with BxGradB down).
Publisher:
ISBN:
Category :
Languages : en
Pages : 24
Book Description
The dependence of L-H power threshold on magnetic topology (upper-, lower-null) in a tokamak is linked to near-sonic plasma flows in the high-field side scrape-off layer. Scrape-off layer flow momentum, coupling across the separatrix, imparts a topology-dependent increment to edge and core toroidal rotation (counter-, co-current). In all topologies, rotation increases in the co-current direction with input power: the L-H transition is seen when co-rotation achieves a characteristic level. Correspondingly, higher power is required to attain H-modes in upper- versus lower-null (with BxGradB down).
Modelling of the Impurity Flow in the Tokamak Scrape-off Layer
Author: J. Neuhauser
Publisher:
ISBN:
Category :
Languages : en
Pages : 27
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 27
Book Description
Detached Scrape-off Layer Tokamak Plasmas
Author: Jay Kesner
Publisher:
ISBN:
Category :
Languages : en
Pages : 24
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 24
Book Description
Radiative Instabilities in the Tokamak Scrape-off Layer During Edge-localized Mode Activity
Author: Per O. F. Helander
Publisher:
ISBN:
Category :
Languages : en
Pages : 30
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 30
Book Description
Simulation of Plasma Flow in the DIII-D Tokamak
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 7
Book Description
The importance of the parallel flow of primary and impurity ions in the Scrape-Off layer (SOL) of divertor tokamaks has been recognized recently. Impurity accumulation on the closed flux surfaces is determined in part by their parallel flow in the SOL. In turn, the parallel transport of the impurity ions is determined in part by drag from the primary ion flow. Measurement of flow in the DIII-D tokamak has begun recently. We describe initial results of modeling plasma ion flow using the 2-D code UEDGE in this paper. We assume the impurity (carbon) arises from chemical and physical sputtering from the walls surrounding the DIII-D plasma. We include six charge states of carbon in our simulations. We make detailed compaison with a multitude of SOL plasma diagnostics, including the flow measurement, to verify the UEDGE physics model. We begin the paper with a brief description of the plasma and neutral models in the UEDGE code in Section 2. We then present initial results of flow simulations and compare them with experimental measurement in Section 3. We conclude with a discussion of the dominant physics processes identified in the modeling in Section 4.
Publisher:
ISBN:
Category :
Languages : en
Pages : 7
Book Description
The importance of the parallel flow of primary and impurity ions in the Scrape-Off layer (SOL) of divertor tokamaks has been recognized recently. Impurity accumulation on the closed flux surfaces is determined in part by their parallel flow in the SOL. In turn, the parallel transport of the impurity ions is determined in part by drag from the primary ion flow. Measurement of flow in the DIII-D tokamak has begun recently. We describe initial results of modeling plasma ion flow using the 2-D code UEDGE in this paper. We assume the impurity (carbon) arises from chemical and physical sputtering from the walls surrounding the DIII-D plasma. We include six charge states of carbon in our simulations. We make detailed compaison with a multitude of SOL plasma diagnostics, including the flow measurement, to verify the UEDGE physics model. We begin the paper with a brief description of the plasma and neutral models in the UEDGE code in Section 2. We then present initial results of flow simulations and compare them with experimental measurement in Section 3. We conclude with a discussion of the dominant physics processes identified in the modeling in Section 4.
The influence of biasing on the flows in the core and the scrape-off layer of a Tokamak
Author: Michel Van Schoor
Publisher:
ISBN:
Category :
Languages : fr
Pages : 0
Book Description
Publisher:
ISBN:
Category :
Languages : fr
Pages : 0
Book Description
Scaling of the Tokamak Near Scrape-off Layer H-mode Power Width and Implications of ITER
Author: Thomas Eich
Publisher:
ISBN:
Category : Nuclear fusion
Languages : en
Pages : 13
Book Description
Publisher:
ISBN:
Category : Nuclear fusion
Languages : en
Pages : 13
Book Description