Download or read book The Multipulse Thomson Scattering Diagnostic on the DIII D Tokamak written by and published by . This book was released on 1991 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes the design and operation of a 40-spatial channel Thomson scattering system that uses multiple 20 Hz Nd:YAG lasers to measure the electron temperature and density profiles periodically throughout an entire plasma discharge. Interference filter polychromators disperse the scattered light which is detected by silicon avalanche photodiodes. The measurable temperature range from 10 eV to 20 keV and the minimum detectable density is about 2 x 1018 m−3. Laser control and data acquisition are performed in real-time by a VME-based microcomputer. Data analysis is performed by a MicroVAX 3400. Unique features of this system include burst mode'' operation, where multiple lasers are fired in rapid succession (

Download or read book Design and Operation of the Multipulse Thomson Scattering Diagnostic on DIII D written by and published by . This book was released on 1992 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes the design and operation of a 40 spatial channel Thomson scattering system that uses multiple 20 Hz Nd:YAG lasers to measure the electron temperature and density profiles periodically throughout an entire plasma discharge. As many as eight lasers may be fired alternately for an average measurement frequency of 160 Hz, or they may be fired in rapid succession (

Download or read book Progress on the Multipulse Thomson Scattering Diagnostic on DIII D written by and published by . This book was released on 1994 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The DIII-D Thomson scattering diagnostic, operational since 1990, uses 8 Nd: YAG 20 Hz lasers to measure electron temperature and density profiles (40 spatial points) throughout the plasma discharge. Recent progress has enabled a new set of operating modes to better fullfill varying plasma physics requirements. Custom circuitry for laser control (programmable with los precision) has successfully replaced a previous scheme which used real-time 68030 software. Two new modes of operation have been demonstrated. Burst Mode is useful to study a transient plasma event: a series of laser pulses axe fired at a rate (less-than or equal to)10 kHz after an external asynchronous event trigger. Burst Mode is also useful to synchronize the Thomson lasers with other systems, such as an asynchronous Michelson ECE diagnostic scanning near 40 Hz. Group Mode allows a programmed set of lasers to fire simultaneously into the same (65 nanosecond) data acquisition gate. Improved signal/noise then yields smaller statistical errors in the profile results. This provides profile data for lower density plasmas, such as those anticipated during fast wave current drive experiments. Plans for a new CCD-based laser alignment system for position monitoring and feedback control will also be presented.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Initial Operation of the Divertor Thompson Scattering Diagnostic on DIII D written by and published by . This book was released on 1996 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first Thomson scattering measurements of n{sub e} and T{sub e} in the divertor region of a tokamak are reported. These data are used as input to boundary physics codes such as UEDGE and DEGAS and to benchmark the predictive capabilities of these codes. These measurements have also contributed to the characterization of tokamak disruptions. A Nd:YAG laser (20 Hz, 1 J, 15 ns, 1064 nm) is directed vertically through the lower divertor region of the DIII-D tokamak. A custom, aspherical collection lens (f /6.8) images the laser beam from 1-21 cm above the target plates into eight spatial channels with 1.5 cm vertical and 0.3 cm radial resolution. 2D mapping of the divertor region is achieved by sweeping the divertor X-point location radially through the fixed laser beam location. Fiber optics carry the light to polychromators whose interference filters have been optimized for low T{sub e} measurements. Silicon avalanche photo diodes measure both the scattered and plasma background light. Temperatures and densities are typically in the range of 5-200 eV and 1 - 10 x 1019 m−3 respectively. Low temperatures, T{sub e} 1 eV, and high densities, n{sub e} 8x102° m−3 have been observed in detached plasmas. Background light levels have not been a significant problem. Reduction of the laser stray light permits Rayleigh calibration. Because of access difficulties, no in-vessel vacuum alignment target could be used. Instead, an in situ laser alignment monitor provides alignment information for each laser pulse. Results are compared with Langmuir probe measurements where good agreement is found except for regions of high n{sub e} and low T{sub e} as measured by Thomson scattering.

Download or read book Modeling and Analysis of the DIII D Tokamak Scrape off Layer and Divertor written by Quang Thanh Nguyen and published by . This book was released on 1995 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Collective Thomson Scattering Energetic Particle Diagnostic in High Performance Tokamaks Final Report written by and published by . This book was released on 1997 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report summarizes the work performed under DOE grant DE-FG03-95ER54334. Lodestar was an active participant in the low power Collective Thomson Scattering (CTS) diagnostic experiment at TFTR in collaboration with MIT. A simple and effective fitting technique was developed to extract key parameters from the scattered data. Utilizing this new technique, the concept of lower hybrid resonance scattering was adapted for a feasibility study of a low/medium power collective scattering diagnostic for ITER. The implementation and the testing of such a technique for actual parameter extraction using TFTR data, however, was severely limited due to experimental and instrumentation complications. Based on the studies the authors have performed up to date, it is believed that a combination of non-physics related effects such as multiple wall reflection of incident signal and spectral impurity problem o the gyrotron can account for the anomalous signal strength. A collaborative effort with GA was initiated and a feasibility study of developing and implementing a collective thomson scattering (CTS) diagnostic for the detection of energetic particles at DIII-D was completed. Specifically, the process of selecting an optimum receiver location for the diagnostic is discussed in detailed. Results presented here include detailed signal to noise calculations and ray-tracing studies. Critical physics issues and selection criteria are discussed and a procedure to detect anisotropic energetic ion temperatures is also outlined. Favorable results, obtained in the feasibility study, indicate that it should be possible to develop and implement a CTS diagnostic at DIII-D.

Download or read book Central Thomson Scattering Upgrade on DIII D written by and published by . This book was released on 1997 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The existing 36 channel Thomson scattering system on the DIII-D tokamak measures the plasma temperature and density in the core region. However, with the recent interest in core peaked density profiles, coverage needs to be extended into the magnetic axis. This paper addresses the technical issues involved with extending the viewing region from a major radius of 194 cm to 165 cm. At least one of the existing seven core laser beams will be rerouted to probe the plasma horizontally instead of vertically. To do this, a rigid extension of the existing laser/collection optics tower will be built to route the laser to a nearby tangential port. A fiber bundle array from one of the two existing core plasma collection optics sets will be rotated to allow up to 10 of the 36 core channels to view along this new beam path. A new in-vessel absorbing glass laser dump must be developed since there are no appropriate laser beam exit ports. The close proximity of this laser dump to the viewing region presents stray light issues that must be resolved to allow for an accurate density calibration using Rayleigh scattering in argon gas.

Download or read book An Instrument to Sychronize Thomson Scattering Diagnostic Measurements with MHD Activity in a Tokamak written by Alan L. Wintenberg and published by . This book was released on 1984 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Dite Tokamak Multi pulse Thomson Scattering System written by R. Prentice and published by . This book was released on 1978 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1995 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics Briefs written by and published by . This book was released on 1992 with total page 820 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advanced Diagnostics for Magnetic and Inertial Fusion written by Peter E. Stott and published by Springer Science & Business Media. This book was released on 2011-06-28 with total page 449 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the International Conference on Advanced Diagnostics for Magnetic and Inertial Fusion, held September 3-7, 2001 at Villa Monastero, Varenna, Italy. This volume focuses on future diagnostic requirements for fusion energy research emphasizing advanced diagnostics, new techniques and areas where further progress is required.

Download or read book An Instrument to Synchronize Thomson Scattering Diagnostic Measurements with MHD Activity in a Tokamak written by Alan L. Wintenberg and published by . This book was released on 1985 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design of the Multi point Thomson Scattering Diagnostic for the HIT II Experiment written by Chris Hoffman and published by . This book was released on 1998 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Annual Index written by and published by . This book was released on 1992 with total page 1228 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book First Fifty Pps Thomson Scattering Diagnostics in a Tokamak written by Kurt Hirsch and published by . This book was released on 1981 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: