The relation of carbon influxes and core carbon concentrations in ASDEX upgrade [Elektronische Ressource] / Si-Woo Yoon

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The Relation of Carbon Influxesand Core Carbon Concentrationsin ASDEX UpgradeSi-Woo YoonMax-Planck-Institut fur Plasmaphysik¨Experimentelle Plasmaphysik 4The Relation of Carbon Influxes and CoreCarbon Concentrations in ASDEX UpgradeSi-Woo YoonVollst¨andiger Abdruck der von der Fakulta¨t fu¨r Physikder Technischen Universit¨at Mu¨nchenzur Erlangung des akademischen Grades einesDoktors der Naturwissenschaften (Dr.rer.nat.)genehmigten Dissertation.Vorsitzender: Univ.-Prof. Dr. P. VogelPrufer der Dissertation: 1. Hon.-Prof. Dr. R. Wilhelm¨2. Univ.-Prof. Dr. E. NolteDie Dissertation wurde am 26.6.2003 bei derTechnischen Universitat Munchen eingereicht und¨ ¨durch die Fakultat fur Physik am 16.9.2003 angenommen.¨ ¨AbstractUnderstanding the impurity behavior in a tokamak plasma is one of themajor tasks on the route to the successful development of a fusion reactor.Carbon is the major impurity species in present tokamak plasmas includingASDEX Upgrade, since major parts of the first wall are covered with gra-phite. Carbon transport can be divided into three parts: the sources fromthe plasma wall interactions, the transport in the plasma edge region, andthe core transport. In this thesis, the relation of carbon influxes to the corecarbon concentrations is studied in ASDEX Upgrade plasma discharges.Optical emission spectroscopy is used for the measurements of the car-boninfluxes,inadditiontothedeuteriuminfluxes.

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• Physik

Informations

• Publié par: technische_universitat_munchen
• Publié le: 01 janvier 2003
• Nombre de lectures: 28
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

The Relation of Carbon Influxes and Core Carbon Concentrations in ASDEX Upgrade

Si-Woo Yoon

Max-Planck-Institutfu ¨ rPlasmaphysik Experimentelle Plasmaphysik 4

The Relation of Carbon Influxes and Core Carbon Concentrations in ASDEX Upgrade

Si-Woo Yoon

Vollst ¨ andigerAbdruckdervonderFakulta ¨ tfu ¨ rPhysik derTechnischenUniversita ¨ tMu ¨ nchen zur Erlangung des akademischen Grades eines Doktors der Naturwissenschaften (Dr.rer.nat.) genehmigten Dissertation.

Vorsitzender:

Pru ¨ ferderDissertation:

Univ.-Prof. Dr. P. Vogel

1. Hon.-Prof. Dr. R. Wilhelm

2. Univ.-Prof. Dr. E. Nolte

Die Dissertation wurde am 26.6.2003 bei der TechnischenUniversit ¨ atMu ¨ ncheneingereichtund durchdieFakult ¨ atf ¨ urPhysikam16.9.2003angenommen.

Abstract

Understanding the impurity behavior in a tokamak plasma is one of the major tasks on the route to the successful development of a fusion reactor. Carbon is the major impurity species in present tokamak plasmas including ASDEX Upgrade, since major parts of the first wall are covered with gra- phite. Carbon transport can be divided into three parts: the sources from the plasma wall interactions, the transport in the plasma edge region, and the core transport. In this thesis, the relation of carbon influxes to the core carbon concentrations is studied in ASDEX Upgrade plasma discharges.

Optical emission spectroscopy is used for the measurements of the car- bon influxes, in addition to the deuterium influxes. The proportional constant between influxes and the photon intensities, i.e, the inverse photon efficiency, are derived from the collisional-radiative modeling (ADAS). The core carbon concentrations are calculated from the soft-X ray measurements of CVI with the assumption of coronal equilibrium. The two-dimensional plasma edge si- mulation code (B2.5) is utilized to interpret the spectroscopic measurements. A fit routine of B2.5 is developed to determine the transport coefficients at the outer midplane of ASDEX Upgrade, which are required for a self-consistent description of the edge plasma.

Based on the finding of this thesis, the carbon sources from the divertors are negligible to the main chamber source. This is concluded from both the analytic and the computational calculations and also from the experimental database of the standard H-modes in ASDEX Upgrade. Although the inner heat shield are tungsten coated, according to the radial magnetic scan expe- riments and Zeeman analysis, the carbon sources from the inner heat shield are dominant. The transport coefficients at the plasma boundary region are determined using the B2.5 fit routine. For carbon ions, an inward pinch is required to match the measurements. Finally, the effect of the edge localized mode on influxes is discussed.

Acknowledgements

I am indebted to my scientific advisor, Prof. Dr. Arne Kallenbach for his scientific guidance. He has enlightened me via valuable discussions and bril- liant suggestions. If my thesis is something readable, it’s mainly due to his patience and support throughout my graduate course.

I would like to thank my academic advisor, Prof. Dr. Rolf Wilhelm for his kindness to correct my thesis. I am grateful to Prof. Dr. K. Behringer for providing opportunity to work with the ASDEX Upgrade team.

I am also grateful to Dr. David Coster and Dr. Jeong Won Kim for their support and guidance for B2 code and the physics inside. I thank my col- leagueDr.RobertoPugnoandMr.TomasPu ¨ tterichfortheirsupportand advice about the experimental works. I would like to thank Dr. Rudolf Neu, Dr. Ralf Dux, Dr. Hans Meister, Dr. Alex Geier for their useful discussions andsuggestions.IthankDr.J ¨ urgenGafertforhissupportfortheZeeman analysis. The special thank is to Frau. Gabriele Daube who helped everything about living in Garching.

Finally, I would like to express thanks to my family with all my heart, my son Dong-Hyun and my wife Sung-Hye who support me with endless love all the time, especially for my wife.

Contents

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Introduction 1.1 Thermonuclear Fusion . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Tokamak : A Toroidal Magnetic Plasma Confinement Device . . . . . . 1.3 Divertors and Impurities . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 Previous Work and Motivation . . . . . . . . . . . . . . . . . . . . . . . 1.5 Scope of This Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

General Mechanisms of Carbon Transport in ASDEX Upgrade 2.1 Release Mechanism of Carbon at the Plasma Facing Components . . . 2.2 Transport in the Scrape-off Layer Region . . . . . . . . . . . . . . . . . 2.2.1 Transport Parallel to the Magnetic Field Line . . . . . . . . . . 2.2.2 Transport Perpendicular to the Magnetic Field Line . . . . . . .

3 3 4 5 8 9

11 12 15 15 19

Measurements of Carbon Influxes and Concentrations 21 3.1 Principle of Spectroscopic Measurements of the Influxes . . . . . . . . . 21 3.1.1 Description of Line Integrated Photon Fluxes . . . . . . . . . . 21 3.1.2 The Relation of Photon and Particle Flux . . . . . . . . . . . . 23 3.1.3 ADAS: a Collisional Radiative Model for Atomic Data Evaluations 24 3.2 Experimental Setup for Measurements of the Influxes . . . . . . . . . . 25 3.2.1 Visible Survey Spectrometers (VSL, VSM) . . . . . . . . . . . . 25 3.2.2 High and Low Resolution Spectrometers (CDL, CDH) . . . . . . 25 3.2.3 Photomultipliers (DIV) . . . . . . . . . . . . . . . . . . . . . . . 27 3.2.4 Limiter Spectroscopy (LVS) . . . . . . . . . . . . . . . . . . . . 27 3.2.5 The Installed Lines of Sight . . . . . . . . . . . . . . . . . . . . 27 3.2.6 Spectroscopic Measurements of the Carbon Concentrations in- side the Separatix (COM) . . . . . . . . . . . . . . . . . . . . . 27 3.2.7 Electron Density and Temperature at Outer Midplane from Thom- son Scattering Measurements . . . . . . . . . . . . . . . . . . . 30

Adaptation of the B2.5 code and the Fit Procedure 4.1 B2.5 : a Two Dimensional Fluid Plasma Edge Transport Code . . . . . 4.1.1 A short Description of the B2.5 code . . . . . . . . . . . . . . .

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