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
  • 1
    Electronic Resource
    Electronic Resource
    Nonlinear reflection in a bandpass filter (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 4327-4332 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is shown that a nonlinear lumped-circuit transmission line with a bandpass can transmit weak signals and reflect strong signals. Such nonlinear bandpass filters have an absolute limit on the power passed and may prove useful as circuit protectors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344949
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    High-detectivity GaAs quantum well infrared detectors with peak responsivity at 8.2 μm (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 7608-7611 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaAs quantum well infrared detectors with peak responsivity at 8.2 μm and significant response beyond 10 μm have been demonstrated with detectivities of 4×1011 cm (Hz)1/2 /W at 6 K; this detectivity is the highest reported for a quantum well detector. The detectors comprised 50 GaAs quantum wells of width 40 A(ring) with an average Si doping density of 1×1018 cm−3 separated by 280-A(ring) barriers of Al0.28Ga0.72As. In this design, the state to which electrons are excited by infrared absorption and from which they are subsequently collected lies in the continuum above the energy of the Al0.28Ga0.72As conduction-band minimum. The maximum detector responsivity was mesured to be 0.34 A/W. The device dark current density is 5.5×10−6 A/cm2 with the detector biased for maximum detectivity (3.5 V), and the dark current remains constant with increasing temperature up to 50 K. The detector noise current was observed to be a constant fraction (70%) of the shot noise down to noise currents of 10−14 A/(Hz)1/2. A theoretical model for the dark conduction process in a quantum well detector has been developed which successfully predicts the observed dark current noise.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345829
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Nonideal theory of toroidal Alfvén eigenmodes (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 356-372 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ambiguities in the ideal magnetohydrodynamic (MHD) analysis of toroidal Alfvén eigenmodes (TAE) are resolved by incorporating nonideal effects (finite electron conductivity and ion gyroradius) into the MHD model of Rosenbluth et al. [Phys. Fluids B 4, 1806 (1992)]. The previous ideal theory yields a dielectric function containing branch points in the complex frequency plane, but provides no specification of the corresponding branch lines. The kinetic model represents a singular perturbation of the ideal theory, and specifies precisely the location of branch cuts in the ideal limit. Moreover, the analytic structure of the complex frequency plane for the kinetic model shows a countably infinite set of poles in place of a branch cut—with a new kinetic-type TAE mode near each pole. It has also been verified that the ideal frequency root is in most cases close to one of the kinetic roots. The damping and mode structure is determined numerically within the framework of the high-mode-number, small inverse aspect ratio, low beta, small gyroradius model. Finally, an analytic form for the damping is obtained including both continuum and nonideal effects, and agrees well with the numerical results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870838
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Analytical model of the "tilting'' instability (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 222-224 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Tilting instability is an instability of convective motion in two-dimensional (2-D) ideal fluid transforming convection into sheared flow. An analytical model of the tilting instability is proposed that clearly exhibits inverse cascade phenomenon, conserving both energy and enstrophy. Obtained solution describes the evolution of the nonlinear stage in which initial fluid convection is transformed completely into the large-scale flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870824
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    A numerical study of the Alfvén continuum damping of toroidal Alfvén eigenmodes (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 1214-1225 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Alfvén continuum damping of the toroidal Alfvén eigenmodes is explicitly formulated for a large aspect ratio force-free tokamak using analytic continuation. A set of jump conditions across the Alfvén singularities are derived which have to be satisfied by the mode amplitudes. The method is then applied to a simple model equilibrium. The characteristics of the modes and their damping are investigated. The method is expected to be generalizable to models with more complete plasma dynamics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870718
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Unified theory of ballooning instabilities and temperature gradient-driven trapped ion modes (1991)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 1807-1817 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A unified theory of temperature gradient-driven trapped ion modes and ballooning instabilities is developed using kinetic theory in banana regimes. All known results such as electrostatic and purely magnetic trapped particle modes and ideal magnetohydrodynamic ballooning modes (or shear Alfvén waves) are readily derived from the present single general dispersion relation. Several new results from ion–ion collision, finite beta stabilization of ion temperature gradient-driven trapped particle modes, and trapped particle modification of ballooning modes are derived and discussed. The interrelationship between these modes is established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859650
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Tearing modes in tokamaks with lower hybrid current drive (1991)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 363-371 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper, the effect of current drive on the tearing modes in the semicollisional regime is analyzed using the drift-kinetic equation. A collisional operator is developed to model electron parallel conductivity. For the pure tearing modes the linear and quasilinear growth rates in the Rutherford regimes have been found to have roughly the same forms with a modified resistivity as without current drive. One interesting result is the prediction of a new instability. This instability, driven by the current gradient inside the tearing mode layer, is possibly related to magnetohydrodynamic (MHD) behavior observed in these experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859746
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Stability of ion-temperature-gradient-driven modes in the presence of sheared poloidal flows (1992)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 2402-2413 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The linear theory of the sonic ion-temperature-gradient-driven mode in the presence of sheared poloidal rotation is discussed in the context of a hydrodynamic model. Analytical and numerical calculations show that the growth rate increases for weak shear, but then decreases when the shearing frequency exceeds the mode frequency. This trend is a consequence of the coupling of radial eigenmodes induced by the asymmetric effective potential and the absorption and damping due to resonance between the wave frequency and shearing frequency. The former dominates at weak shear, resulting in destabilization, while the latter dominates for strong shear, resulting in stabilization. Mixing length estimates of the turbulent diffusivity are given, and a novel bifurcation scenario for the L→H transition is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860209
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Mode structure and continuum damping of high-n toroidal Alfvén eigenmodes* (1992)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 2189-2202 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An asymptotic theory is described for calculating the mode structure and continuum damping of short-wavelength toroidal Alfvén eigenmodes (TAE). The formalism somewhat resembles the treatment used for describing low-frequency toroidal modes with singular structure at a rational surface, where an inner solution, which for the TAE mode has toroidal coupling, is matched to an outer toroidally uncoupled solution. A three-term recursion relation among coupled poloidal harmonic amplitudes is obtained, whose solution gives the structure of the global wave function and the complex eigenfrequency, including continuum damping. Both analytic and numerical solutions are presented. The magnitude of the damping is essential for determining the thresholds for instability driven by the spatial gradients of energetic particles (e.g., neutral-beam-injected ions or fusion-product alpha particles) contained in a tokamak plasma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860023
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    A kinetic theory of trapped-electron-driven drift wave turbulence in a sheared magnetic field (1991)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 68-86 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A kinetic theory of collisionless and dissipative trapped-electron-driven drift wave turbulence in a sheared magnetic field is presented. Weak turbulence theory is employed to calculate the nonlinear electron and ion responses and to derive a wave kinetic equation that determines the nonlinear evolution of trapped-electron mode turbulence. The saturated fluctuation spectrum is calculated using the condition of nonlinear saturation. The turbulent transport coefficients (D, χi, χe), are, in turn, calculated using the saturated fluctuation spectrum. Because of the disparity in the three different radial scale lengths of the slab-like eigenmode: Δ (trapped-electron layer width), xt (turning point width), and xi (Landau damping point), Δ〈xt〈xi, it is found that ion Compton scattering rather than trapped-electron Compton scattering is the dominant nonlinear saturation mechanism. Ion Compton scattering transfers wave energy from short to long wavelengths where the wave energy is shear damped. As a consequence, a saturated fluctuation spectrum ||φ||2(kθ)∼k−αθ (α=2 and 3 for the dissipative and collisionless regimes, respectively) occurs for kθ ρs〈1 and is heavily damped for kθ ρs〉1. The predicted fluctuation level and transport coefficients are well below the "mixing length'' estimate. This is due to the contribution of radial wave numbers x−1t〈kr≤ρ−1i to the nonlinear couplings, the effect of radial localization of the trapped-electron response to a layer of width Δ, and the weak turbulence factor 〈γle/ωk〉k〈1, which enters the saturation level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859957
    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...