Coskun Firat

Universality of the quantum boundary layer for a Maxwellian gas

For an ideal gas confined in a rectangular domain, it has been shown that the density is not homogenous even in thermodynamic equilibrium and it goes to zero within a layer near to the boundaries due to the wave character of particles. This layer has been called the quantum boundary layer (QBL). In literature, an analytical expression for the thickness of QBL has been given for only a rectangular domain since both energy eigenvalues and eigenfunctions of the Schrodinger equation can analytically be obtained for only a rectangular domain. In this study, ideal Maxwellian gases confined in spherical and cylindrical domains are considered to investigate whether the thickness of QBL is independent of the domain shape. Although the energy eigenvalues are the roots of Bessel functions and there is no analytical expression giving the roots, the thickness of QBL is expressed analytically by considering the density distributions and using some simplifications based on the numerical calculations. It is found that QBL has the same thickness for the domains of different shapes. Therefore, QBL seems to have a universal thickness independent of the domain shape for an ideal Maxwellian gas.

Quantum forces of a gas confined in nano structures

In nano domains, thermodynamic properties of gases considerably differ from those in macro domains. One of the reasons for this difference is the quantum size effects, which become important when the thermal de Broglie wavelength of particles is not negligible in comparison with domain size. In this study, it is shown that quantum forces may appear in gases confined in nano structures due to the quantum boundary layer caused by quantum size effects. In the case of experimental verification of these quantum forces, a macroscopic manifestation of the effect of the quantum boundary layer on the thermodynamic behavior of gases can be confirmed.

Cosmic ray intensity variation during a CME

Abstract The June 6, 2000 coronal mass ejection was an exceptional full halo, which made it possible to measure cosmic ray (CR) decrease with a simple experimental set-up. Variation in the local secondary cosmic ray density has been investigated by means of gamma rays. The experiment site was located in Istanbul (41.1N, 29.0E). CR electrons and slow gamma rays have been eliminated. The CR density has dropped drastically starting on June 8, 2000. The counts have been compared with the pre-shock levels and some other cases of CMEs. During strong solar modulation, the local counts of secondary CR intensity values dropped down as much as 24%.

Thermodynamic properties of a photon gas confined in hypothetical arbitrary-shaped perfectly reflecting nano-scale geometries

In nano scale, thermodynamic properties of gases show difference from those in macro scales. One of the reasons of this difference is the quantum size effects (QSE), which become significant when compared with the thermal de Broglie wavelength of particles to the characteristic length of the system. In this study, thermodynamic behavior of a photon gas confined in a nanoscale domain is examined in terms of QSE. It is obtained that due to quantum size effects the global thermodynamic properties of a photon gas confined in a nano scale domain are different than those in macro scale. The matter of QSE on thermodynamics of substances at micro/nano scale is relatively a new research area and the new findings might lead to significant new applications.