Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Response of internal transport barriers to central electron heating and current drive on ASDEX Upgrade : The 41st annual meeting of the division of plasma physics of the american physical society (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 7 (2000), S. 1839-1844 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Internal transport barriers with the central electron temperature as large as the central ion temperature both in excess of 10 keV have been achieved in the Axi-symmetric divertor experiment (ASDEX Upgrade) [H. Vernickel et al., J. Nucl. Mater. 128, 71 (1984)]. By applying central electron cyclotron heating and current drive to negative central shear discharges, established by neutral beam heating in the current ramp, the core electron temperatures could be raised by more than a factor of 2. Despite the fivefold increase of the central electron heat flux, the ion and electron energy and also angular momentum transport did not deteriorate. For neutral beam injection alone and also with additional central electron cyclotron counter-current drive, a double tearing mode and the associated detrimental effect on the plasma confinement is destabilized only transiently, when the minimum of the safety factor (qmin) passes through 2. For co-current drive, however, the confinement does not recover after qmin has dropped below 2, as the (2,1) mode persists due to the influence of the current profile modification in the very plasma center. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.874006
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The relation of edge confinement to global confinement in ASDEX Upgrade (Axially Symmetric Divertor Experiment) (1997)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 4 (1997), S. 2577-2583 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experimental evidence is presented from the ASDEX Upgrade (Axially Symmetric Divertor Experiment) tokamak [Plasma Physics and Controlled Nuclear Fusion Research 1993 (International Atomic Energy Agency, Vienna, 1994), Vol. I, p. 127] of a robust relation between the edge radial pressure gradient and the global confinement of the plasma. This relation transcends the power flowing across flux surfaces near the edge and thus suggests that the usual model of cross-field heat transport, where local gradients increase with increasing local power flow, is not appropriate. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872403
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    A self-calibration technique for a Thomson scattering system : Proceedings of the eleventh topical conference on high temperature plasma diagnostics (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 725-727 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A self-calibration technique, based on the use of two lasers of different wavelengths is described. Such a scheme is essential in the presence of inaccessible optical components, as found on large present day machines. In these devices spectral characteristics may change with time, posing a problem for the calibration of a Thomson scattering diagnostic. From a combination of the scattered spectra generated by the two lasers on the same plasma, the temperature and the unknown, slowly varying spectral transmission of the different channels can be determined. A visible wavelength scattering system on a high-temperature plasma is assumed with laser wavelengths of 800 and 530 nm. Details of the analysis procedure and the results of fitting for the unknown spectral calibrations are presented. A statistical analysis of the error in the fitted calibration curve is included. A practical solution, with reference to ITER, is proposed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147686
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Improvements in the evaluation of Thomson scattering data on ASDEX upgrade : Papers from the thirteenth topical conference on high temperature plasma diagnostics (2001)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 72 (2001), S. 1111-1114 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The avalanche diodes used as light detectors in the Thomson scattering diagnostic on the Axially Symmetric Divertor Experiment (ASDEX) Upgrade tokamak show a reduced signal-to-noise ratio during plasma discharges with high neutron rates and during plasma edge measurements. This often makes it impossible to determine the electron temperature from the ratios of the scattering signals of the different spectral channels analyzing the Thomson scattering spectrum. With the use of the maximum likelihood method combined with linearized electron temperature characteristics the electron temperature and density are determined directly from the scattering signals without calculating ratios between the signals. With this method the scattering signals for nearly all timepoints can be evaluated and the statistical errors of the electron temperature and density are up to factors of 2 and 1.4, respectively, smaller than achieved with the previous method. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1321747
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    The LIDAR Thomson scattering diagnostic on JET (invited) (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1451-1456 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: By combining the time-of-flight or LIDAR principle with a Thomson backscatter diagnostic, spatial profiles of the electron temperature and density are measured in a magnetically confined fusion plasma. This technique was realized for the first time on the JET tokamak. A ruby laser (3-J pulse energy, 300-ps pulse duration, 0.5-Hz repetition rate) together with a 700-MHz bandwidth detection and registration system yields a spatial resolution of about 12 cm. A spectrometer with six channels in the wavelength range 400–800 nm gives a dynamic range of the temperature measurements of 0.3–20 keV. The stray light problem in the backscatter geometry is overcome by spectral discrimination and gating of the photomultipliers. A ruby filter in the spectral channel containing the laser wavelength allows calibration of the vignetting along the line of sight by means of Raman scattering, enabling the measurement of density profiles. The low level of background signal due to the short integration time for a single spatial point yields low statistical errors (ΔTe /Te ≈6%, Δne /ne ≈4% at Te =6 keV, ne =3×1019 m−3 ). Goodness-of-fit tests indicate that the systematic errors are within the same limits. The system is described and examples of measurements are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139686
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Excess noise of the R 928 photomultiplier (1987)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 58 (1987), S. 136-138 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The noise factor of the HAMAMATSU R 928 circular cage photomultiplier has been measured. It is demonstrated that the optimum mode of operation with respect to the noise is the one with constant interstage voltage distribution. Different effects contributing to the overall noise factor have been identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139543
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Time-of-flight Thomson backscattering technique for large fusion devices (1985)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 1030-1032 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The application of 180° Thomson scattering to the JET tokamak for measuring electron temperature and density profiles is discussed. Spatial resolution along the laser beam is achieved by the use of subnanosecond laser pulses and high-speed detection allowing time-of-flight measurements. Gating tests of MCP photomultiplier and measurements of the stray light level in a full-scale optical setup show that the severe stray light problem in a backscatter geometry can be handled. Tests of a frequency-doubled iodine laser system are reported which demonstrate that a 1-pps operation of the system is feasible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138258
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Shutter ratio of a gated ITT F4128 microchannel-plate photomultiplier (1987)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 58 (1987), S. 2339-2341 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The shutter ratio of a proximity focused ITT F4128 microchannel-plate (MCP) photomultiplier is investigated for gated photocathode-to-MCP gap voltages. At counter potentials of greater than 3 V, the shutter ratio is better than 1013 for incident light with a wavelength longer than 600 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139298
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    A high-resolution Lidar–Thomson scattering diagnostic for JET : Eighth topical conference on high−temperature plasma diagnostics (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 2843-2845 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A LIDAR–Thomson scattering system with better than 5 cm spatial resolution to resolve edge electron temperature and density gradients in H-mode operation in JET is needed. A dynamic range in measurable electron temperature of 0.1–1.5 keV and a minimum detectable electron density of 1019/m3 are required. To achieve these levels of performance, it is planned to use a modified section of the existing JET LIDAR–Thomson scattering system. A new detection system, consisting of a streak camera and an intensifier unit, will be used. Spectral dispersion is to be performed by a three-channel edge filter spectrometer. Recording and digitization of the scattered signal will be performed by a CCD camera read out by a personal computer. The system is described and results of experiments to determine the minimum visible light levels using a commercial streak camera, intensifier unit, and CCD camera and a pulsed laser diode light source are briefly presented. In addition, simulations of expected signal-to-noise ratio performance are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141801
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    A new method for estimating and identifying systematic error in Thomson scattering diagnostics : Eight topical conference on high-temperature plasma diagnostics (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 2849-2851 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method has been developed to identify and estimate systematic error in the calibration of Thomson scattering systems. The basis of the technique is an iterative recalculation of electron temperature using successively more self-consistent calibrations. A computational method was developed to calculate from a large dataset a calibration correction factor for each channel. The correction factor was then applied and the fitting routine rerun on the whole dataset with the new calibration factors. The resulting frequency distribution of chi-squared values was close to the theoretical distribution while the calculated electron temperatures were changed by only 1 to 2%. The technique succeeded in identifying and quantifying errors in a dataset known to be of poor quality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141803
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...