Author: Brian LaBombardPublisher:
ISBN:
Category :
Languages : en
Pages : 11
Book Description
Transport Studies in the Scrape-off Layer and Divertor of Alcator C-Mod
Author: Brian LaBombardTokamaks
Author: John WessonPublisher: Oxford University Press
ISBN: 0199592233
Category : Science
Languages : en
Pages : 828
Book Description
The tokamak is the principal tool in controlled fusion research. This book acts as an introduction to the subject and a basic reference for theory, definitions, equations, and experimental results. The fourth edition has been completely revised, describing their development of tokamaks to the point of producing significant fusion power.
Plasma Flows in the Alcator C-Mod Scrape-off Layer
Author: Noah M. SmickPublisher:
ISBN:
Category :
Languages : en
Pages : 234
Book Description
(Cont.) Toroidal rotation, Pfirsch-Schlilter and transport-driven contributions are unambiguously identified. Parallel flows are found to dominate the high-field particle fluxes; the total poloidally-directed flow carries one half of the particle flux arriving on the inner divertor. As a result, convection is also found to be an important player in high-field side heat transport. In contrast, E_r x B plus parallel flows yield a mostly-toroidal flow component in the low-field SOL. The magnitude of the transport-driven flow component is found to be quantitatively consistent with radial fluctuation-induced particle fluxes measured on the low-field side, identifying this as the primary driver. In contrast, fluctuation-induced flux measurements on the high-field side midplane are found to be essentially zero, thereby excluding an 'inward pinch' effect as the mechanism that closes the mass-flow loop in this region.
Scientific and Technical Aerospace Reports
Author: Impurity Plume Experiments in the Edge Plasma of the Alcator C-Mod Tokamak
Author: Sanjay GangadharaPublisher:
ISBN:
Category :
Languages : en
Pages : 86
Book Description
The physics of impurity transport in response to a local gas injection in the scrape-off-layer (SOL) of Alcator C-Mod is investigated. Carbon "plumes'' are formed at variable locations in the SOL -- up to the separatrix -- by puffing deuterated ethylene gas (C2D4) through the end of a reciprocating fast-scanning probe. CCD cameras are used to simultaneously record C+1 and C+2 emission patterns from two near-perpendicular views. The plume dispersal patterns are found to yield direct qualitative information about plasma flow, including the direction of VExB near the separatrix. Impurity transport and plasma-surface interaction physics implicit in the 3-D plume structure is explored in detail using a Monte Carlo impurity transport code, with the aim of extracting background plasma-flow quantities. A number of important local effects involving plasma-probe interaction have been identified: a vertical ExB drift near the probe surface, a parallel electric field above the probe tip arising from plasma recycling off the probe surface, and sputtering of a carbon layer that dynamically forms on the probe surface. The emission patterns are also found to yield important information on flows in the SOL: radial electric field (Er) in the near SOL and volume-averaged values of the parallel Mach number in the far SOL. Er values obtained from plume data compare favorably with estimates of Er based on the poloidal propagation velocity of edge plasma fluctuations measured by the scanning probe. Comparisons between parallel Mach numbers obtained from the plume data and probe measurements indicate that the probe over-estimates the parallel flow towards the divertor in the far SOL. This result supports the picture of particle balance in the SOL of Alcator C-Mod being dominated by main-chamber recycling, with weak plasma flow into the divertor.
Fusion Energy 1996
Author: International Atomic Energy AgencyPublisher: Fusion Energy 1996
ISBN: 9789201007971
Category : Business & Economics
Languages : en
Pages : 954
Book Description
Proceedings of the Sixteenth International Conference, formerly called the International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Montreal, 7-11 October 1996. The papers presented reflect the excellent progress achieved since the last conference in Seville 1994. Among many other achievements, the Tokamak Fusion Test Reactor has produced over 10 MW of fusion power, the JT-60U experiment has demonstrated plasma conditions equivalent to breakeven, the reversed shear mode has been demonstrated, low aspect ratio tokamaks have produced promising results and plans have been drawn up for powerful new inertial confinement fusion experiments.
Scientific and Technical Aerospace Reports
Author: The Dynamics of Electrons in Linear Plasma Devices and Its Impact on Plasma Surface Interaction
Author: Michael HubenyPublisher: Springer
ISBN: 303012536X
Category : Science
Languages : en
Pages : 137
Book Description
Turbulence in plasma surface interaction holds crucial uncertainties for its impact on material erosion in the operation of fusion reactors. In this thesis, the design, development and operation of a Thomson scattering diagnostic and its novel implementation with fast visual imaging created a versatile tool to investigate intermittently occuring plasma oscillations. Specifically, ballistic transport events in the plasma edge, constituting turbulent transport, have been targeted in this thesis. With the help of a custom photon counting algorithm, the conditional averaging technique was applied on Thomson scattering for the first time to allow spatial and pseudo-time-resolved measurements. Since plasma turbulence and the emerging transport phenomena are comparable in most magnetized devices, the diagnostic development and the results from the linear plasma device PSI-2 are useful for an implementation of similar techniques in larger fusion experiments. Furthermore, the obtained results indicate a strong enhancement of erosion with turbulent transport and thus underline the importance of dedicated experiments investigating plasma turbulence in the framework of erosion in future fusion reactors.
Metals Abstracts
Author: Investigation of the Origin of Neutrals in the Main Chamber of Alcator C-Mod
Author: B. LipschultzPublisher:
ISBN:
Category :
Languages : en
Pages : 36
Book Description
A series of experiments are described which are aimed at quantifying the relative contribution of divertor leakage and radial ion transport on neutral pressures surrounding the core plasma. Evidence is presented implying that cross-field transport competes with, or dominates, parallel transport in such a way that plasma exists far out in the Scrape-Off Layer (SOL) in the shadow of limiters and recycles on main chamber surfaces. The transition from L- to H-mode core confinement does not affect the far SOL characteristics nor the scaling of pressures around the plasma. Variations in magnetic equilibrium are used to vary the divertor pressures independent of the core plasma. Based on the analysis of such experiments using a simple neutral flow model we estimate that neutrals escaping from leaks in the lower (closed) divertor during lower x-point operation contribute a smaller fraction ... of the midplane pressure than main chamber recycling. The inferred leakage is much larger from the upper (open) divertor during upper x-point operation. Most neutrals escaping from either divertor do not directly travel to the midplane. Instead, they are redirected, most likely by some combination of ionization and/or collisions (elastic, charge exchange).