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## Full-Text Articles in Physics

Thermodynamics Of Integrable Chains With Alternating Spins, H. J. De Vega, Luca Mezincescu, Rafael I. Nepomechie

#### Thermodynamics Of Integrable Chains With Alternating Spins, H. J. De Vega, Luca Mezincescu, Rafael I. Nepomechie

*Physics Articles and Papers*

We consider a two-parameter (c¯,c̃) family of quantum integrable isotropic Hamiltonians for a chain of alternating spins of spin s=1/2 and s=1. We determine the thermodynamics for low-temperature T and small external magnetic field H, with T≪H. In the antiferromagnetic (c¯>0,c̃>0) case, the model has two gapless excitations. In particular, for c¯=c̃, the model is conformally invariant and has central charge c_{vir}=2. When one of these parameters is zero, the Bethe ansatz equations admit an infinite number of solutions with lowest energy.

Numerical Simulation Of Nonequilibrium Effects In An Argon Plasma Jet, C. H. Chang, John D. Ramshaw

#### Numerical Simulation Of Nonequilibrium Effects In An Argon Plasma Jet, C. H. Chang, John D. Ramshaw

*Physics Faculty Publications and Presentations*

Departures from thermal (translational), ionization, and excitation equilibrium in an axisymmetric argon plasma jet have been studied by two?dimensional numerical simulations. Electrons, ions, and excited and ground states of neutral atoms are represented as separate chemical species in the mixture. Transitions between excited states, as well as ionization/recombination reactions due to both collisional and radiative processes, are treated as separate chemical reactions. Resonance radiation transport is represented using Holstein escape factors to simulate both the optically thin and optically thick limits. The optically thin calculation showed significant underpopulation of excited species in the upstream part of the jet ...

Thermodynamics Of A Free Q Fermion Gas, Asim Gangopadhyaya

#### Thermodynamics Of A Free Q Fermion Gas, Asim Gangopadhyaya

*Asim Gangopadhyaya*