ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

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
Filter
  • 1995-1999  (15)
  • 1990-1994  (29)
  • 1910-1914  (2)
Collection
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Stochastic ion behavior in subharmonic and superharmonic electrostatic waves (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 1545-1568 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dynamics of a charged particle in a magnetic field perturbed by electrostatic waves propagating transverse to the magnetic field has been investigated. Depending on the number of perturbing waves, the magnitude of the perturbation and the perturbation frequency (ν=r/s=ω/ω0, where r and s are relatively prime integers, and ω0 is the cyclotron frequency), the particle motion can exhibit either a small deviation from simple cyclotron motion or stochastic motion over phase space. The latter case is found to correspond to particle heating and anomalous transport. In the case of cyclotron harmonic perturbations (superharmonic case, s=1), the phase space of the particle is covered by a stochastic web, inside of which the particle motion is chaotic. The particle can, in principle, be heated to very high energy. However, if the wave frequency is some fraction of the ion cyclotron frequency (subharmonic case, s≥2), the heating range is limited. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872014
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Plasma diagnostics for the DIII-D divertor upgrade : Eighth Topical Conference on High−Temperature Plasma Diagnostics (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 3548-3551 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The DIII-D tokamak is being upgraded to allow for divertor biasing, baffling, and pumping experiments. This paper gives an overview of the new diagnostics added to DIII-D as part of this advanced divertor program. They include tile current monitors, fast reciprocating Langmuir probes, a fixed probe array in the divertor, fast neutral pressure gauges, and Hα measurements with TV cameras and fiber optics coupled to a high-resolution spectrometer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141568
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    A fast scanning probe for DIII–D : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4728-4730 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A fast reciprocating probe has been developed for DIII–D which can penetrate the separatrix during H mode with up to 5 MW of NBI heating. The probe has been designed to carry various sensor tips into the scrape-off layer at a velocity of 3 m/s and dwell motionless for a programmed period of time. The driving force is provided by a pneumatic cylinder charged with helium to facilitate greater mass flow. The first series of experiments have been done using a Langmuir probe head with five graphite tips to measure radial profiles of ne, Te, φf, ñe, and φ˜f. The amplitude and phase of the fluctuating quantities are measured by using specially constructed vacuum compatible 5-kV coaxial transmission lines which allow us to extend the measurements into the MHz range. TTZ ceramic bearings and fast stroke bellows were also specially designed for the DIII–D probe. Initial measurements will be presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143621
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    An omegatron mass spectrometer for plasma ion species analysis (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 2155-2158 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An omegatron mass spectrometer which can be used to measure the ion species and charge state distribution in a magnetized plasma is described. In the conventional omegatron, ions are formed as the result of gas ionization by a fine electron beam passing through the center of the analyzer along the magnetic field. In the plasma omegatron, the plasma ions are entering the analyzer through a small floating aperture. We employ a biasing technique to reduce the ion velocity along the magnetic field and, thus, achieve improved ion collection and sensitivity. Experiments have been performed to demonstrate the instrument's operation in the PISCES-A linear plasma device, at a magnetic field B=1.3 kG. Mass spectra have been obtained in hydrogen, helium, and nitrogen plasmas, and typical results are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141382
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Plasma and neutral dynamics in a simulated tokamak gas target divertor (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 3081-3094 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A stationary, detached ionization front is observed in an experimentally simulated divertor plasma (n≤3×1019 m−3, kTe≤20 eV) interacting with a hydrogen gas target. With a neutral hydrogen density, n0≈2×1021 m−3, the electron temperature at the simulated divertor target is reduced to kTe target≈2.5 eV. Up to 97% of the electron heat flux (≤7 MW/m2) is dissipated by dissociation and ionization losses and hydrogen line radiation. The plasma pressure is observed to peak near the ionization front, and a plasma flow reversal is observed in the region of reversed pressure gradient. Classical momentum flow parallel to the magnetic field and anomalous cross-field particle transport are found. The plasma flow is strongly damped by ion–neutral collisions and is subsonic. Numerical results from a one-and-one-half dimensional (11/2-D) coupled plasma–neutral fluid model (incorporating radial particle transport, recycling, and neutral gas injection) agree well with the experimental data, and indicate that the electron heat flow is classical and well described by a harmonic flux limit. The scale length of the parallel plasma pressure gradient in a gas target is found to depend on the neutral density, the electron temperature, and the cross-field diffusion coefficient. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871206
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Turbulent edge transport in the Princeton Beta Experiment-Modified high confinement mode (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 3301-3307 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The first probe measurements of edge turbulence and transport in a neutral beam induced high confinement mode (H-mode) are reported. A strong negative radial electric field is directly observed in H-mode. A transient suppression of normalized ion saturation and floating potential fluctuation levels occurs at the low confinement mode to high confinement mode (L–H) transition, followed by a recovery to near low mode (L-mode) levels. The average poloidal wave number and the poloidal wave-number spectral width are decreased, and the correlation between fluctuating density and potential is reduced. A large-amplitude coherent oscillation, localized to the strong radial electric field region, is observed in H-mode but does not cause transport. In H-mode the effective turbulent diffusion coefficient is reduced by an order of magnitude inside the last closed flux surface and in the scrape-off layer. The results are compared with a heuristic model of turbulence suppression by velocity-shear stabilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870916
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Collisionless Simon–Hoh instability in a strongly double-sheared electric field (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 3193-3198 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It has been shown in an earlier paper [Phys. Fluids B 5, 344 (1993)] that the ion flow speed of a plasma can be much smaller than the E×B speed in a strongly double-sheared electric field. In this paper, the stability of the plasma is investigated. It is found that a new instability, driven by the difference between the ion and electron flow speed, occurs and may dominate the Kelvin–Helmholtz (KH) instability in a nonuniform plasma. This new instability has a driving mechanism similar to that of the Simon–Hoh instability and is thus called the collisionless Simon–Hoh (CSH) instability. When the CSH instability dominates, the plasma does not become more unstable as the electric field is increased, in contrast to scenarios where the KH instability is dominant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870473
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Radial electric field required to suppress ion temperature gradient modes in the Electric Tokamak (1999)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 6 (1999), S. 4722-4727 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Electric Tokamak (ET), currently under construction at the University of California–Los Angeles, is designed to rotate poloidally via a radial current induced by fast wave rf heating fast enough to bifurcate the plasma into a global "H mode" ("high confinement mode"). A global gyrokinetic code is used to explore and illustrate some of the effects on ion temperature gradient turbulence. The realistic radial electric field required to completely suppress these modes for ET parameters is demonstrated to be 〈−30 V/cm at its maximum near the half radius. The effects of both a poloidally supersonic bulk rotation threshold and the shear in this rotation near that supersonic threshold were shown to be important in reducing these modes. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.873759
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Effect of elastic scattering on stochastic ion heating by electrostatic waves (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 1569-1577 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dynamics of an ion interacting with an electrostatic wave propagating perpendicularly to a static magnetic field in the presence of elastic ion-neutral scattering is investigated. Superharmonic (ω/ω0∈I) and subharmonic (ω/ω0=r/s≤1) perturbations are studied. Here, ω and ω0 are the wave and the ion cyclotron frequency, respectively, and r and s are relatively prime integers. Without elastic collisions, the ion is found to exhibit either quasi-regular or stochastic motion in phase space depending on the wave frequency, wave amplitude, and the initial position and velocity of the particle. Quasi-regular and stochastic behavior are found to be exclusive with respect to each other. In the presence of elastic collisions, the entire phase space becomes accessible to the ion irrespective of the initial conditions. The heating rate is generally found to depend on the ratio γm/ω (where γm is the momentum loss rate) and is enhanced compared to the collisionless case. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872015
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    On the influence of atomic physics mechanisms on edge plasma turbulence in the TJ-I and Princeton Beta Experiment-Modified tokamaks (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 2618-2620 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The role of neutrals as a driving force of plasma turbulence was investigated in the TJ-I tokamak [Phys. Fluids B 5, 4051 (1993)]. No influence of the local neutral source strength on fluctuation levels was found, neither in the plasma bulk side nor in the scrape-off layer side of the velocity shear layer location. Helium puffing was used to study the influence of impurity radiation on turbulence in the Princeton Beta Experiment-Modified (PBX-M) [Plasma Physics and Controlled Nuclear Fusion Research 1988 (International Atomic Physics Agency, Nice, 1989), Vol. 1, p. 97]. Evidence of fluctuation levels modified increasing He-impurity radiation was obtained. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871225
    Location Call Number Expected 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...