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Results for “Finite Temperature or Finite Density”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Multi-ion resonances in finite temperature plasma

Dispersion properties of electrostatic waves in a multi-ion plasma are examined, with an analysis that incorporates the effects of finite temperature, finite parallel wavenumber, and wave growth/damping in a systematic development of equations. Numerical solutions and analytic formulas are given for an ion plasma consisting of H(+), O(+), and S(+) for application to Jupiter's magnetosphere. It is demonstrated how observations of plasma resonance lines may be used as a diagnostic of ion composition in magnetospheric plasma. This potential use of high-sensitivity/high-resolution plasma wave instrumentation may provide information necessary to resolve issues concerning the origin of plasmas in the earth's neighborhood.

Barbosa, D. D.↗
NASA NTRS1992

Entropic uncertainty relation at finite temperature

We discussed how much information is lost when a particle is in equilibrium with the thermal reservoir of temperature T = 1/beta. The universal temperature correction to the r.h.s. of U(X,P:psi) greater than or = 1 + ln(pi) is determined. For this purpose, it is convenient to employ the framework of thermo-field dynamics (TFD). This formulation of finite-temperature (T not = 0) quantum theory utilizes the doubled Hilbert space, the normal operator (A) acting on the objective space, and its corresponding tildian operator on the fictitious space. The physical probability density associated with the measurement of the normal operator, A, is given, and the information entropy at T not = 0 is defined. The results describe how the thermal disturbance effects in S sub X or S sub P (delta X or delta P) can be suppressed by squeezing with keeping U = S sub X + S sub P (delta X x delta P) its minimum value.

Abe, Sumiyoshi↗
NASA NTRS1972

Thermodynamics of hydrogen-helium mixtures at high pressure and finite temperature

A technique is reviewed for calculating thermodynamic quantities for mixtures of light elements at high pressure, in the metallic state. Ensemble averages are calculated with Monte Carlo techniques and periodic boundary conditions. Interparticle potentials are assumed to be coulombic, screened by the electrons in dielectric function theory. This method is quantitatively accurate for alloys at pressures above about 10 Mbar. An alloy of equal parts hydrogen and helium by mass appears to remain liquid and mixed for temperatures above about 3000 K, at pressures of about 15 Mbar. The additive volume law is satisfied to within about 10%, but the Gruneisen equation of state gives poor results. A calculation at 1300 K shows evidence of a hydrogen-helium phase separation.

Hubbard, W. B.↗
NASA NTRS1985

The lateral surface drag coefficient of cylindrical spacecraft in a rarefied finite temperature atmosphere

In the present determination of the free molecule flow drag coefficient for a cylindrical spacecraft flying parallel to its principal axis, the lateral surface effects of thermal motion are explicitly included in terms of the average impact angle of the incident gas momentum vector. Kinetic theory is used to characterize self-shadowing, as well as to obtain an expression for the lateral surface coefficient in terms of the average impact angle of the incident momentum vector and the fractional momentum transfer along the line of impact. It is found that, for a length/diameter ratio of about 5, the lateral surface contribution to the drag coefficient is comparable to that of the front face.

Herrero, F. A.↗
NASA NTRS1990

Chiral interface at the finite temperature transition point of QCD

The domain wall between coexisting chirally symmetric and broken symmetry regions is studied in a saddle point approximation to the effective three-flavor sigma model. In the chiral limit the surface tension varies in the range ((40 to -50)MeV)(exp 3). The width of the domain wall is estimated to be approximately or equal to 4.5 fm.

Frei, Z.↗
NASA NTRS1977

Prediction of the bulk temperature in spur gears based on finite element temperature analysis

The temperature distribution in spur gears operating in a state of thermal equilibrium is solved by using a finite element method. The effects of various dimensionless parameters on bulk temperature are shown. A table is provided which can be used to predict the bulk temperature on gear teeth, once the heat transfer coefficients and frictional heat input is estimated. Theoretical results for estimating heat transfer coefficients and frictional heat are also summarized.

Patir, N.↗