2,698 research outputs found
Radiation data definitions and compilation for equipment qualification data bank
Dose definitions, physical properties, mechanical properties, electrical properties, and particle definitions are listed for insulators and dielectrics, elastomeric seals and gaskets, lubricants, adhesives, and coatings
On the thermoelastic analysis of solar cell arrays and related material properties
Accurate prediction of failure of solar cell arrays requires accuracy in the computation of thermally induced stresses. This was accomplished by using the finite element technique. Improved procedures for stress calculation were introduced together with failure criteria capable of describing a wide range of ductile and brittle material behavior. The stress distribution and associated failure mechanisms in the N-interconnect junction of two solar cell designs were then studied. In such stress and failure analysis, it is essential to know the thermomechanical properties of the materials involved. Measurements were made of properties of materials suitable for the design of lightweight arrays: microsheet-0211 glass material for the solar cell filter, and Kapton-H, Kapton F, Teflon, Tedlar, and Mica Ply PG-402 for lightweight substrates. The temperature-dependence of the thermal coefficient of expansion for these materials was determined together with other properties such as the elastic moduli, Poisson's ratio, and the stress-strain behavior up to failure
Glass for low-cost photovoltaic solar arrays
Various aspects of glass encapsulation that are important for the designer of photovoltaic systems are discussed. Candidate glasses and available information defining the state of the art of glass encapsulation materials and processes for automated, high volume production of terrestrial photovoltaic devices and related applications are presented. The criteria for consideration of the glass encapsulation systems were based on the low-cost solar array project goals for arrays: (1) a low degradation rate, (2) high reliability, (3) an efficiency greater than 10 percent, (4) a total array price less than $500/kW, and (5) a production capacity of 500,000 kW/yr. The glass design areas discussed include the types of glass, sources and costs, physical properties, and glass modifications, such as antireflection coatings
Influence of Disorder on the Hall Effect in BiSrCuO
The in-plane resistivity and Hall coefficient have been measured for the
single-layer compound BiSrCuO for the whole range of
doping states. The deviation of the Hall coefficient, , from a
high-temperature linear behavior and the temperature dependence of the Hall
angle are both only weakly dependent upon doping, contrasting with
BiSrLaCuO and BiSrCaCuO. This
is in contradiction with former proposals that the transverse transport detects
the formation of incoherent Cooper pairs in the pseudogap state. Conversely,
the analysis of the data using a phenomenological angular dependent scattering
rate clearly allows to distinguish between underdoped and overdoped states, and
we propose that the maximum in simply arises due to the combination of
a large isotropic scattering rate and an anisotropic temperature dependent one
Current dependent fluctuations in a BiSrCuO thin film
The current dependence of the excess conductivity is measured up to for a BiSrCuO thin film, as a function of doping. It
is found to be anomalously sensitive to the transport current and to behave as
a universal function of in the whole doping range. We discuss these
results in the perspective of a granular superconductor with a gapless-like
behavior
Vortex-glass transition in superconducting Nb/Cu superlattices
Nb/Cu superconducting superlattices have been fabricated by dc magnetron
sputtering. This system shows a vortex glass transition with critical exponents
similar to high temperatures superconductors exponents. The transition
dymensionality is governed by the superconducting coupling regime. The vortex
glass transition shows a pure two dimensional behavior in decoupled
superlattices and a quasi-two dimensional behavior in the superlattice coupling
regime.Comment: 9 pages, 3 figure
Magnetoresistance and Hall effect in e-doped superconducting SrLaCuO thin films
We have epitaxially grown c-axis oriented SrxLa1-xCuO2 thin films by rf
sputtering on KTaO3 substrates with x = 0.12. The as-grown deposits are
insulating and a series of superconducting films with various Tc(R=0) up to 26
K have been obtained by in-situ oxygen reduction. Transport measurements in the
ab plane of these samples have been undertaken. We report original results on
the temperature dependence of the Hall effect and on the anisotropic
magnetoresistance (T > Tc). We discuss the magnitude of upper critical fields
and anisotropy, the Hall effect, which presents changes of sign indicative of
the existence of two types of carriers, the normal state magnetoresistance,
negative in parallel magnetic field, a possible signature of spin scattering.
These properties are compared to those of hole-doped cuprates, such as
BiSr(La)CuO with comparable Tc.Comment: 4 pages, 4 figures; to appear in Proceedings of LT25, Journal of
Physics : Conference Serie
Penetration depth of electron-doped-infinite-layer SrLaCuO thin films
The in-plane penetration depth of SrLaCuO thin
films at various doping obtained from oxygen reduction has been measured, using
AC susceptibility measurements. For the higher doping samples, the superfluid
density deviates strongly from the s-wave behavior, suggesting, in analogy with
other electron-doped cuprates, a contribution from a nodal hole pocket, or a
small gap on the Fermi surface such as an anisotropic s-wave order parameter.
The low value of the superfluid densities, likely due to a strong
doping-induced disorder, places the superconducting transition of our samples
in the phase-fluctuation regime
Upper critical field from normal state fluctuations in BiSrCuO
The in-plane magnetoresistance of an epitaxial BiSrCuO
thin film was systematically investigated as a function of doping, above .
The orbital magnetoconductance is used to extract the crossover field line
in the fluctuation regime. This field is found in good agreement
with the upper critical field obtained from resistivity data below , and
exhibits a similar upward curvature, thus pointing toward the existence of a
critical correlation length. The consequences regarding the nature of the
resistive transition are discussed
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