Author: Joseph Frank CamachoPublisher:
ISBN:
Category :
Languages : en
Pages : 135
Book Description
Soft X-ray Tomography on the Alcator C Tokamak
Author: Joseph Frank CamachoPublisher:
ISBN:
Category :
Languages : en
Pages : 135
Book Description
Edge Plasma Phenomena in the Alcator C-Mod Tokamak Measured by High Resolution X-ray Imaging Diagnostics
Author: Thomas Sunn PedersenPublisher:
ISBN:
Category :
Languages : en
Pages : 206
Book Description
(cont.) A second array views the top of the plasma. The x-ray emissivity measured with this array also shows a distinct and narrow pedestal in H-mode. However, it is located significantly closer to the separatrix and is often narrower. Both of these differences increase with the safety factor at the edge, q95. Thus, there is a significant poloidal asymmetry in the impurity density in the H-mode edge region, which increases with q95. Therefore, the impurity transport in the H-mode edge is highly two-dimensional. The strong poloidal asymmetries measured show some quantitative agreement with theories developed to explain poloidal impurity asymmetries. However, none of the theories are strictly applicable to the Alcator C-Mod edge, and they all significantly underestimate the actual asymmetries that we observe.
Soft X-ray Measurements in the Alcator C Tokamak
Author: Linda Meryl StoloffPublisher:
ISBN:
Category : Detectors
Languages : en
Pages : 58
Book Description
Fusion Energy Update
Author: Energy Research Abstracts
Author: Tokamak Physics Studies Using X-ray Diagnostic Methods
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
X-ray diagnostic measurements have been used in a number of experiments to improve our understanding of important tokamak physics issues. The impurity content in TFTR plasmas, its sources and control have been clarified through soft x-ray pulse-height analysis (PHA) measurements. The dependence of intrinsic impurity concentrations and Z/sub eff/ on electron density, plasma current, limiter material and conditioning, and neutral-beam power have shown that the limiter is an important source of metal impurities. Neoclassical-like impurity peaking following hydrogen pellet injection into Alcator C and a strong effect of impurities on sawtooth behavior were demonstrated by x-ray imaging (XIS) measurements. Rapid inward motion of impurities and continuation of m = 1 activity following an internal disruption were demonstrated with XIS measurements on PLT using injected aluminum to enhance the signals. Ion temperatures up to 12 keV and a toroidal plasma rotation velocity up to 6 x 105 m/s have been measured by an x-ray crystal spectrometer (XCS) with up to 13 MW of 85-keV neutral-beam injection in TFTR. Precise wavelengths and relative intensities of x-ray lines in several helium-like ions and neon-like ions of silver have been measured in TFTR and PLT by the XCS. The data help to identify the important excitation processes predicted in atomic physics. Wavelengths of n = 3 to 2 silver lines of interest for x-ray lasers were measured, and precise instrument calibration techniques were developed. Electron thermal conductivity and sawtooth dynamics have been studied through XIS measurements on TFTR of heat-pulse propagation and compound sawteeth. A non-Maxwellian electron distribution function has been measured, and evidence of the Parail-Pogutse instability identified by hard x-ray PHA measurements on PLT during lower-hybrid current-drive experiments.
Experimental Plasma Research Project Summaries
Author: Publisher:
ISBN:
Category : Plasma (Ionized gases)
Languages : en
Pages : 144
Book Description
Reconstruction of Soft X-ray and Tungsten Concentration Profiles in Tokamaks Using Gaussian Process Tomography
Author: Tianbo WangPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Aiming at the development of a sustainable and safe energy source, nuclear fusion research is presently largely concentrated around the construction and operation of the international ITER project. One of the primary issues threatening safe and efficient operation of tokamaks, is the accumulation of so-called impurities in the plasma core, causing fuel dilution and radiative power loss. In this doctoral work, a new method has been developed and applied for reconstruction of soft X-ray radiation distribution in poloidal cross-section by means of Gaussian processes (GPs), which can deliver the information about impurity concentrations in tokamak plasmas. The method was tested on synthetic and real data and was found to compare favorably with standard techniques, at greatly reduced computational cost. Concentration of tungsten was also inferred and neural network approximations were investigated, opening perspectives for real-time impurity control in tokamaks.
Soft X-Ray Imaging Study on Disruptions in the JIPP T-II Tokamak
Author: Shunji TsujiEdge Plasma Phenomena in the Alcator C-Mod Tokamak Measured by High Resolution X-ray Imaging Diagnostics
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
By Thomas Sunn Pedersen.