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
Collection
Keywords
Publisher
Language
Years
  • 1
    Electronic Resource
    Electronic Resource
    Heteroepitaxial multilayer of YBa2Cu3O7 and PrBa2Cu3O7 on SrTiO3 and LaAlO3 substrates by sputtering (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 2072-2074 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have successfully fabricated epitaxially grown YBa2Cu3O7/PrBa2Cu3O7 (YBCO/PBCO) multilayer thin films on SrTiO3 and LaAlO3 substrates by dc/rf magnetron sputtering. The thicknesses of YBCO and PBCO varied from 1 to 8 unit cells. Satellite peaks in x-ray diffraction patterns clearly indicate the formation of periodic modulation structures of different wavelengths. At a certain thickness of the YBCO layer, the zero resistance transition temperature Tc0 decreased with the increase of the PBCO layer thickness. In contrast, Tc0 increased with the increase of the YBCO layer thickness at a constant PBCO layer thickness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351640
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Critical current and flux pinning near Tc of a YBa2Cu3O7 thin film (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 2461-2463 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The voltage V versus current I of a high-quality YBa2Cu3O7−x thin film with zero-resistance temperature equal to 90.8 K was measured at temperatures near Tc (85, 87, and 90 K, respectively) under different magnetic fields (0–7 T). A significant result is that the critical-current density of the film reached 1.37×104 A/cm2 (zero field) even at 90 K, implying that strong pinning centers exist in our sample. However, a small applied magnetic field will diminish the critical-current densities remarkably. The pinning-force densities are found to follow Kramer's scaling law in both perpendicular and parallel directions of the magnetic fields to the c axis of the film. A possible influence of thermally activated flux creep on the pinning mechanism is confirmed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349400
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Critical current measurements in YBa2Cu3O7−x thin film grown on LaAlO3 substrate (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 884-886 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The critical current density Jc(B,T) of epitaxial YBa2Cu3O7−x (YBCO) thin films on LaAlO3 was measured under different applied magnetic fields (0–7 T) with the temperature ranging from 65 to 79 K. At 65 K, the zero-field critical current density of the best film was 5.8×106 A/cm2; even at magnetic fields up to 7 T, Jc could reach as high as 1×106 A/cm2. Strong anisotropy was observed at 79 K. The anisotropy behavior diminished with the decrease of temperature. Experimental results showed that Jc was proportional to (Tc−T)3/2 ; this was in accordance with the theoretical explanation by the Josephson junction model for granular superconductors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346784
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Synergistic effects of the safety factor and shear flows on development of internal transport barriers in reversed shear plasmas (2002)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 9 (2002), S. 748-751 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new suppression mechanism of turbulent transport, characteristic of the synergism between safety factor and shear flows, is proposed to explain the internal transport barriers (ITBs) observed in neutral-beam-heated tokamak discharges with reversed magnetic shear. It is shown that the evolution of turbulent transport with the strength of the suppression mechanism reproduces the basic features of the formation and development of ITBs observed in experiments. In addition, the present analyses predict the possibility of global ion and electron heat transport barriers. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1445753
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Lagrangian invariants of trapped electron dynamics in tokamaks (2001)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 5-7 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The trapped electron dynamics is considered in general tokamak magnetic field with positive or reversed shear. Starting from the continuity, energy-evolution, and motion equations of the trapped electron fluid and the definition of Lagrangian invariant, the Lagrangian invariants hidden in the dynamics are strictly found: L=ln[(n/B)c1(T/B2/3)c2], where c1 and c2 are dimensionless changeable parameters and c1∝c2. It yields n/B=const and T3/2/B=const. Further, based on them it is shown that 〈n〉ψq(ψ)=const and 〈T3/2〉ψq(ψ)=const. The former invariant qualitatively fits the experimental data in many tokamaks; the latter may be used to explain the steady-state hollow T-profile (the corresponding hollow j-profile) observed in reversed shear tokamak plasmas. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1331565
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Model for relaxation in reversed-field pinch plasmas (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 2316-2330 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this article, a model for anomalous ion heating, a dynamo current-sustained edge toroidal field, and a sawtooth oscillation during the relaxation in the reversed-field pinch (RFP) plasma is presented. The dynamo (α), the turbulent resistivity (β) and viscosity (χ), dependent on the magnetohydrodynamics (MHD) fluctuations, are incorporated into the model. Turbulent viscous dissipation of the fluctuation energy is proposed as the mechanism of the anomalous ion heating. This is a straightforward corollary of the turbulent viscosity heating of ions in that the temperature of the heavier ions is higher than that of the lighter ions and that the ion temperature increases with the MHD fluctuation level. Correspondingly, the turbulent resistivity heats electrons anomalously. It is shown that the dynamo current, generated by the back-transfer of fluctuating magnetic field helicity to mean magnetic field, sustains the RFP magnetic configuration. In the edge the total current density is approximately equal to the dynamo current density, while at the core the dynamo current opposes the applied electric-field-driven current, flattening the current profile. Provided the α dynamo has a periodic behavior in time, the physical quantities of the RFP plasma have a sawtooth time dependence. The local poloidal current density in the edge increases during the sawtooth crash and peaks at the end of the crash, as do the ion and electron temperatures. In contrast, the toroidal current density at the core decreases during the crash and arrives at its minimum at the end of the crash. Qualitatively, the conclusions drawn from the present model are in good agreement with many of the experimental results [Scime et al., Phys. Rev. Lett. 68, 2165 (1992); Ji et al., ibid. 73, 668 (1994)] and the numerical simulations. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871914
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Finite-β and alpha particle effects on kinetic Alfvén wave in a fusion tokamak plasma (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 2293-2305 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper, a model for the kinetic Alfvén wave (KAW) in the presence of fusion alphas is established. The finite-β (relative to low β) and alpha particle effects on KAW are investigated. In this model, ion sound, transit time magnetic pumping (TTMP), the response of alpha particles (alphas), and those effects considered by preceding authors are included. In cylindrical geometry, a set of three second-order differential equations in r for the perturbed fields Er, E⊥, and E(parallel) is numerically solved. A dispersion relation of the Alfvén wave in the fusion tokamak plasma is derived. The mode conversion and the energy deposition are qualitatively discussed on the basis of this relation. Both the analytical and numerical analyses indicate that (i) no matter whether m (poloidal mode number) is positive [N. Ding et al., Phys. Plasmas 2, 1529 (1995)] or negative (mainly studied in the present paper), the alphas do not affect the compressional Alfvén wave, but they do affect the KAW evidently; (ii) for m〈0, it is preferable to choose the frequency ω of the injected wave so that the inequality ω(approximately-greater-than)(Pm±1/Rm±1)−1ω*αm holds for optimal power absorption. The energy deposition at the resonant position close to the interior of the fusion tokamak plasma in taking account of the effects of ion sound and TTMP is less than that without taking account of these effects. But for the same β value, at the position adjacent to the edge the contrary is the case. For a certain resonant position, as the β value increases, the energy deposition decreases. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871912
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Effects of energetic ions on kinetic Alfvén wave in a tokamak plasma (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 1529-1539 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of energetic ions on the electric field structure and the energy deposition of kinetic Alfvén wave (KAW) in a tokamak plasma are considered. A cylindrical geometry is adopted and a linearized kinetic model including the bulk plasma and the energetic ions is established. These effects of fusion alpha particles (abbreviated, alphas) in deuterium–tritium (D–T) tokamak plasmas are numerically analyzed. The energetic ions tend to alter the wave structure and the energy deposition. The absorption of the kinetic Alfvén wave by the bulk plasma depends sensitively on both the velocity distribution of alphas and the spatial profile of the alpha particle density, as well as on the frequency of the injected wave. Numerical results of the wave structure and the power absorption are given for the parameters of D–T plasmas. The present studies lead to the following discoveries: (1) The slowing-down alpha particle distribution reduces the KAWs energy deposition and the Maxwellian alphas have hardly any influence over it; (2) the more the (slowing-down) alphas near the resonant layer, the more heavily they prevent the KAWs power absorption by the bulk plasma; (3) the lower frequency of the injected wave within the range of KAWs continuum, the more heavily the KAWs structure and power absorption by the bulk plasma are affected by alpha particles; and (4) the energy deposition decreases rapidly as the total number of alphas increases. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871368
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Ion heat pinch in reversed magnetic shear tokamak plasmas (2001)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 1289-1298 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In the well-known reversed shear discharges, it is observed that the ion thermal diffusivity (χi) falls below the standard neoclassical value (χineo), i.e., χi〈χineo. In this paper, local turbulent ion thermal pinch (χit〈0) is proposed as a candidate for interpreting the experimental results from χi=χineo+χit〈χineo. To test the idea, the two-fluid theory, developed by Weiland and the Chalmers group [J. Weiland et al., Nucl. Fusion 29, 1810 (1989); H. Nordman et al., ibid 30, 983 (1990)], is used in the reversed magnetic shear tokamak plasma to study the drift mode and associated ion heat transport. The theory is extended here to include both the radial electrical field shear (dEr/dr) and electron fluid velocity (Ve) in the sheared coordinate system. Remarkably different from B−1dEr/dr, k⋅Ve directly includes the safety factor q as well as the E×B velocity VE itself, where k is the magnetic configuration-dependent wave vector. As a result, the synergetic effects of B−1dEr/dr and k⋅Ve, especially those of k⋅Ve, lead to the local turbulent ion heat pinch in the negative and weak magnetic shear region because of the wave-particle resonance. The impact of B−1dEr/dr and k⋅Ve on the growth rate and ion heat pinch is numerically investigated. Qualitatively, the present results are in good agreement with the experimental trends. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1355676
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    A possible hybrid dissipative trapped electron ion temperature gradient mode (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 3004-3012 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of dissipative trapped electrons on ion temperature gradient-driven instability (ηi mode) in tokamak plasmas are considered. A sheared slab geometry is adopted and a linearized fluid model of ion temperature gradient (ITG) mode including dissipative trapped electrons, which are described by means of the well-known formula of the nonadiabatic electron response [P. L. Similon and P. H. Diamond, Phys. Fluids 27, 916 (1984)], is presented. Results show that in tokamak plasmas not only is there a modification of the dissipative trapped electrons on the ηi mode, but also there may exist an intrinsic oscillation mode, namely, a hybrid dissipative trapped electron ion temperature gradient mode. The higher the dissipative trapped electron fraction, the more it drives the ηi mode, that is, when the trapped electron fraction is sufficient high and the trapped electrons are dissipated strongly, the mode is dominated by the trapped electron dynamics and propagates in the electron diamagnetic direction. These analytical results can be reduced to the usual predictions of the ion temperature gradient-driven instability in the absence of the dissipative trapped electron. Numerical results further show that (a) there may be a hybrid dissipative trapped electron ITG mode and the dissipative trapped electron effect is a destabilizing effect on this mode; and (b) when the trapped electron fraction is sufficiently high and the trapped electrons are dissipated strongly, the mode is determined by the trapped electron dynamics. These conclusions are in agreement with the experimental observations in the latest simulated tokamak experiment on the Columbia Linear Machine [J. Chen and A. K. Sen, Phys. Rev. Lett. 72, 3997 (1994)]. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871635
    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...