Download or read book Design of the Divertor Thomson Scattering System on DIII D written by and published by . This book was released on 1994 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Local measurements of n{sub e} and T{sub e} in the divertor region are necessary for a more complete understanding of divertor physics. We have designed an extension to the existing multipulse Thomson scattering system to measure n{sub e} in the range 5 x 1018 to 5 x 102° m−3 and T{sub e} 5--500 eV, with 1 cm resolution from 1--21 cm above the floor of the DIII-D vessel, in the region of the X-point for lower single-null diverted plasmas. One of the existing 8, 20 Hz, ND:YAG lasers will be redirected to a separate vertical port, and viewed radially with a specially designed, f/6.8 lens. Fiber optics carry the light to additional polychromators whose interference filters have been optimized for low T{sub e} measurements. Other aspect of the system, including the beam path to the vessel, polychromator design, real time data acquisition, laser control, calibration facility, and DIII-D timing and data acquisition interface will be shared with the existing multipulse Thomson system. An in-situ laser alignment monitor will provide alignment information for each laser pulse.
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 First Measurements of Electron Temperature and Density with Divertor Thomson Scattering in Radiative Divertor Discharges on DIII D written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have obtained the first measurements of n[sub e] and T[sub e] in the DIII-D divertor region with a multi-pulse (20 Hz) Divertor Thomson Scattering (DTS) system. Eight measurement locations are distributed vertically up to 21 cm above the divertor plate. Two-dimensional distributions have been obtained by sweeping the divertor plasma across the DTS measurement location. Several operating modes have been studied, including ohmic, L-mode, Elming H-mode, and Radiative Divertor operation with puffing of D[sub 2] and impurities. Mapping of the data to either the (L[sub pol], [phi]) or (R, Z) planes with the EFIT equilibrium is used to analyze the 2D profiles. We find that in ELMing H-mode: n[sub e], T[sub e], and P[sub e] are relatively constant along field lines from the X-point to the divertor plate, especially near the separatrix field line. With D[sub 2] puffing, the DTS profiles indicate that T[sub e] in a large part of divertor region below the X-point is dramatically reduced from[approximately]30-40 eV in ELMing H-mode to 1-2 eV. This results in a fairly uniform low-T[sub e] divertor, with an increased electron density in the range of 2 to 4 x 10[sup 20] m[sup -3]. Detailed comparisons of the spatial profiles of n[sub e], T[sub e], and electron pressure P[sub e], are presented for several operating modes. In addition, these data are compared with initial calculations from the UEDGE fluid code.
Download or read book Reciprocating and Fixed Probe Measurements of N sub E and T sub E in the DIII D Divertor written by and published by . This book was released on 1996 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes divertor density and temperature measurements using both a new reciprocating Langmuir probe (XPT-RCP) which plunges vertically above the divertor floor up to the X-point height and swept, single, Langmuir probes fixed horizontally across the divertor floor. These types of measurements are important for testing models of the SOL and divertor which then are used to design plasma facing components in reactor size tokamaks. This paper presents an overview of the new divertor probe measurements and how they compare with the new divertor Thomson scattering system. The fast time response of the probe measurements allows detailed study of ELMs.
Download or read book Reconstruction of Detached Divertor Plasma Conditions in DIII D Using Spectroscopic and Probe Data written by P. Stangeby and published by . This book was released on 2004 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: For some divertor aspects, such as detached plasmas or the private flux zone, it is not clear that the controlling physics has been fully identified. This is a particular concern when the details of the plasma are likely to be important in modeling the problem--for example, modeling co-deposition in detached inner divertors. An empirical method of ''reconstructing'' the plasma based on direct experimental measurements may be useful in such situations. It is shown that a detached plasma in the outer divertor leg of DIII-D can be reconstructed reasonably well using spectroscopic and probe data as input to a simple onion-skin model and the Monte Carlo hydrogenic code, EIRENE. The calculated 2D distributions of n{sub e} and T{sub e} in the detached divertor were compared with direct measurements from the divertor Thomson scattering system, a diagnostic capability unique to DIII-D.
Download or read book Comprehensive 2D Measurements of Radiative Divertor Plasmas in DIII D written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents a comparison of the total radiated power profile and impurity line emission distributions in the SOL and divertor of DIII-D. This is done for ELMing H-mode plasmas with heavy deuterium injection (Partially Detached Divertor operation, PDD) and those without deuterium puffing. Results are described from a series of dedicated experiments performed on DIII-D to systematically measure the 2-D (R, Z) structure of the divertor plasma. The discharges were designed to optimize measurements with new divertor diagnostics including a divertor Thomson scattering system. Discharge sequences were designed to produce optimized data sets against which SOL and divertor theories and simulation codes could be benchmarked. During PDD operation the regions of significant radiated power shift from the inner divertor leg and SOL to the outer leg and X-point regions. D[alpha] emission shifts from the inner strikepoint to the outer strikepoint. Carbon emissions (visible CII and CIII) shift from the inner SOL near the X-point to a distributed region from the X-point to partially down the outer leg during moderate D2 puffing. In heavy puffing discharges the carbon emission coalesces on the outer separatrix near the X-point and for very heavy puffing it appears inside the last closed flux surface above the X-point. Calibrated spectroscopic measurements indicate that hydrogenic and carbon radiation can account for all of the radiated power. L[alpha] and CIV radiation are comparable and when combined account for as much as 90% of the total radiated power along chords viewing the significant radiating regions of the outer leg.
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 Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Diagnostics for Experimental Thermonuclear Fusion Reactors 2 written by Peter E. Stott and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 615 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book of proceedings collects the papers presented at the workshop on "Diagnostics for Experimental Fusion Reactors" held at Villa Monastero, Varenna (Italy) September 4-12, 1997. This workshop was the seventh organized by the International School of Plasma Physics "Piero Caldirola" on the topic of plasma diagnostics and the second devoted to the diagnostic studies for the International Thermonuclear Experimental Reactor (ITER). The proceedings of the first workshop on ITER diagnostics were published by Plenum Press in 1996 with the title "Diagnostics for Experimental Thermonuclear Fusion Reactors". While many of the ideas and studies reported in the first workshop remain valid, there has been sub stantial progress in the design and specification of many diagnostics for ITER. This moti vated a second workshop on this topic and the publication of a new book of proceedings. ITER is a joint venture between Europe, Japan, Russia and USA in the field of con trolled thermonuclear fusion research. The present aim of ITER is to design an experimental fusion reactor that can demonstrate ignition and sustained burn in a magnetically confined plasma. To achieve this goal, a wide range of plasma parameters will have to be measured reliably. It is also anticipated that diagnostics will be used much more extensively as input to control systems on ITER than on present fusion devices and this will require increased relia bility and long-term stability.
Download or read book Government Reports Annual Index written by and published by . This book was released on 1992 with total page 1232 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 Engineering Design of a Radiative Divertor for DIII D written by and published by . This book was released on 1995 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new divertor configuration is being developed for the DIII-D tokamak. This divertor will operate in the radiative mode. Experiments and modeling form the basis for the new design. The Radiative Divertor reduces the heat flux on the divertor plates by dispersing the power with radiation in the divertor region. In addition, the Radiative Divertor structure will allow density control in plasma shapes required for advanced tokamak operation. The divertor structure allows for operation in either double-null or single-null plasma configurations. Four independently controlled divertor cryopumps will enable pumping at either the inboard (upper and lower) or the outboard (upper and lower) divertor plates. An upgrade to the DIII-D cryogenic system is part of this project. The increased capabilities of the cryogenic system will allow delivery of liquid helium and nitrogen to the three new cryopumps. The Radiative Divertor design is very flexible, and will allow physics studies of the effects of slot width and length. Radiative Divertor diagnostics are being designed in parallel to provide comprehensive measurements for diagnosing the divertor. The Radiative divertor installation is scheduled for late 1996. Engineering experience gained in the DIII-D Advanced Divertor program form a foundation for the design work on the Radiative Divertor.
Download or read book Horizontal Thomson Scattering Systems for DIII D and SSPX written by and published by . This book was released on 1999 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: DIII-D--Three of the seven existing core Thomson scattering laser beams were redirected to probe the previously unmeasured central region of the DIII-D plasma. Modifications to the existing collection optics system and support tower were made to inject the lasers and collect scattered light in this new extended region. Stray light levels were reduced to acceptable levels to permit Rayleigh scattering calibration on five of the six new channels, indicating that the new in-vessel dump operates well. Measurements of the plasma temperature and density from the plasma edge to the center are now possible. Peaked density profiles are now observed in this new measurement region. SSPX--We have completed the design and installation of a 10-spatial channel Thomson scattering system to measure the plasma temperature and density profile on SSPX. A single-pulsed YAG laser operating at 0.7 J and 8 ns is used to scatter photons into a 7-element collection optic that provides a spatial resolution of 1.5 cm at the outer plasma edge and 7.5 cm at the inner edge of a .5 m radius spheromak plasma. The collected light is then analyzed by a 4-channel interference filtered polychromator which has been optimized to measure temperatures between 2 eV and 2 keV and densities as low as 1 x 1012 cm3. We use an in-vessel beam dump and a series of entrance and exit baffles to reduce the stray laser light and provide for an absolute density calibration by Rayleigh scattering in argon gas.
Download or read book Stray Light Reduction Techniques for the Thomson Scattering Diagnostic on the Madison Symmetric Torus written by Adam F. Falkowski and published by . This book was released on 2009 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Grundz ge einer Schulordnung f r die technischen Lehranstalten im K nigreich Bayern written by and published by . This book was released on 1857 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Frances Wildt written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
