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
    High-power, twin-frequency FIR lasers for plasma diagnostic applications (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 1986-1988 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The development of imaging interferometry and multichannel heterodyne scattering systems for fusion plasma diagnosis has dictated the development of high-power, stable twin-frequency sources in the 100→1000 μm spectral region. Output powers of 500 mW (185 μm), 150 mW (393 μm), 100 mW (496 μm), and 25 mW (1.22 mm) have been measured directly on a Scientech Calorimeter applying no correction factors. These powers have been achieved via the optimization of the CO2 and far infrared (FIR) laser cavities together with the use of buffer gases (to relieve bottlenecking) and variation of the pumped molecular gas temperature (to optimize the ground-state population). The source intermediate frequency (IF) jitter in twin-frequency FIR laser systems has also been investigated in detail. The effect of CO2 and FIR feedback on the IF frequency has been studied with the view of producing low-cost stable laser systems without complicated active stabilization. Finally a comparison between a novel twin-frequency laser involving a single optical cavity and a conventional system involving two separate cavities has been performed. The conclusions drawn from the above studies have been utilized in the design of laser systems operational on the TEXT tokamak and at UCLA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139202
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    ECRH absorption and propagation studies via collective Thomson scattering (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 1980-1982 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Electron cyclotron resonance heating (ECRH) has made rapid progress over the last few years due primarily to improved gyrotron source technology. The unique ability of ECRH to deposit energy locally offers numerous advantages, such as the ability to preionize, initiate, control, and heat fusion plasmas. However, wave propagation and absorption mechanisms are not well understood and the fusion community would clearly benefit from a nonperturbing monitor of ECRF wave activity. The use of FIR collective Thomson scattering techniques on the upcoming ECRH experiment on TEXT is described. The intention is to probe both k⊥ and k(parallel) ECRF wave activity as well as simultaneously monitoring microturbulence levels. The existing source frequency of 245 GHz will experience a large frequency shift (∼60 GHz) after scattering from ECRF waves. This has a number of important consequences for the accurate interpretation of scattering data. These will be described in detail as well as alternative CO2 and FIR laser scattering schemes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138812
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Digital complex demodulation applied to interferometry (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 1989-1991 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The objective of this paper is to describe the principles of digital complex demodulation, and to summarize its advantages with respect to rapid time response and insensitivity to noise. These advantages are demonstrated by application to interferometry data collected on the Texas experimental tokamak (TEXT).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138762
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Tokamak ion temperature determination via cw far-infrared laser scattering (1985)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 922-924 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A successful proof-of-principle experimental determination of ion temperature in a tokamak plasma via cw far-infrared (FIR) collective laser scattering from ion Bernstein waves is reported. The Bernstein waves are excited via mode conversion of an externally launched fast Alfven wave at the second-harmonic cyclotron layer. A fit of the experimentally determined ion Bernstein wave dispersion to the temperature-dependent theoretical dispersion yields the local ion temperature. Partial ion temperature profiles (chord averaged) have been obtained with temperature values consistent with charge exchange measurements. Single-shot measurements should be available in the near future with the use of the multichannel scattering systems and high-power laser sources developed at UCLA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138043
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Laser resonant fluorescence scattering in the Toroidal Cusp Experiment (abstract) (1985)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 1071-1071 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A dye laser induced resonant fluorescence scattering system has been installed on the Toroidal Cusp Experiment (TCX) at UCLA. This diagnostic has been employed to perform spatially and temporally resolved measurements of the neutral density and ion temperature. The local volume-average effect is used to decrease the fluctuation level in background radiation, thereby enhancing the signal-to-noise ratio. For Balmer alpha fluorescence measurements, the estimation of the neutral hydrogen density is based on either a coronal model or a time-dependent collisional radiative model depending on plasma parameters. By tuning the laser for broadband operation and using a narrow detection resolution, the ion temperature can be measured. The results are compared with other diagnostics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138224
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Development and application of multichannel collective scattering systems (1985)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 1055-1056 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The numerous applications of cw collective Thomson scattering in fusion plasmas are greatly enhanced by the addition of a multichannel capability. This permits the determination of the dispersive properties (ω vs k) of waves on a single tokamak discharge. This paper describes the development, calibration, and application of such systems in the far-infrared spectral region. The measurement of the wave dispersion of externally excited ion Bernstein waves leads to the determination of ion temperature in a tokamak plasma. In addition, the study of naturally occurring microturbulence has produced a series of unique observations which has both motivated theoretical effort and clarified the role of density fluctuations in anomalous transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138267
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Development of high power, twin frequency far-infrared lasers for fusion diagnostics (abstract) (1985)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 940-940 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Recent developments in plasma diagnostics such as multichannel collective scattering and phase imaging dictate the use of high-power, stable radiation sources in the far-infrared (FIR) spectral region. Towards this end, an optically pumped, twin frequency laser has been developed at UCLA. The CO2 pump laser produces greater than 100 W in a single mode over the majority of the CO2 wavelength range (9–11 μm). The twin frequency FIR laser utilizes a single cavity with two separate dielectric waveguides. The difference frequency (λ=185 μm) is tunable from 0–5 MHz with a short-term stability Δf≤±20 kHz. EH11 spatial modes are routinely achieved with output powers of 100 mW.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138054
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Density profile reconstructions from 2-D interferometric data on Microtor using novel tomographic analysis techniques (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2135-2138 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Plasma tomographic reconstructions are subject to aliasing ambiguity as a result of the limited angular and radial sampling rates for the line-integrated data. The two-view interferometer installed on the Microtor tokamak yields unambiguous information, specifically, a collection of six low-order alias-free moments of the 2-D electron density distribution. The unspoiled coefficients can be related to physically intuitive quantities and so yield information pertinent to the equilibrium and dynamical behavior of the plasma column. Alternatively, they can be used as constraints for a maximum entropy reconstruction of the source to produce an image free of aliasing artifacts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140265
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Core reflectometer density profile measurements on DIII-D : Proceedings of the 12th topical conference on high temperature plasma diagnostics (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1064-1067 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Measurements of core (normalized flux coordinate ρ≤0.3–0.4) electron density profiles have been obtained on the DIII-D tokamak via a reflectometer system operating in the ordinary polarization (O mode). This system was developed and implemented for two primary reasons: first, there is a pressing need for core density profile measurements on DIII-D in plasmas with core transport barriers and centrally peaked profiles, and second, the measurements reported here further extend the demonstrated range of conditions in which reflectometry can provide reliable density profile measurements. As a test of the ability of reflectometry to measure such core profiles an existing DIII-D broadband frequency swept (FMCW) reflectometer system was converted to use O-mode propagation. This test system covers 50–75 GHz, corresponding to densities of 3.1–7.0×1019 m−3. Using this system, core access has been investigated in medium density discharges. Results demonstrate that adequate signals, and hence, accurate profiles, can in fact be obtained to the plasma center in discharges with centrally peaked profiles. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149481
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Laser induced fluorescence measurements in the Pisces plasma (abstract) (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1536-1536 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: By resonantly exciting neutrals in a cool plasma, the local neutral density and possibly ion temperature can be measured. If the neutrals are pumped by a laser with an intensity sufficient to saturate the transition, then observation of the fluorescence at the same wavelength will show an enhancement in the spontaneous emission during the laser pulse. The pump radiation changes the excited level population distribution in such a way that theoretical modeling can extract the ground-state population from the measured enhancement. Here, a 350-kW flash-lamp pumped dye laser is being used at 656 and 481 nm to pump the Balmer alpha and beta lines of hydrogen in the continuous Pisces plasma which simulates the edge using a tokamak. The fluorescence is observed with a photomultiplier tube through a narrow-band interference filter. Great care has been taken to reduce stray light to a negligible level. Data will be presented taken from plasmas with densities between 1011 and 1013 cm−3 and electron temperatures between 5 and 25 eV. In addition, by spectrally resolving the fluorescence, local ion temperatures can be inferred from Doppler broadening. However, actual temperatures measured are close to the resolution limit of the spectrometer. Future work could include these temperature measurements in the edge region of a tokamak. This work was supported by the U.S. DOE Contract No. DE-F03-86-ER-53225.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140189
    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...