Gas-Surface Scattering Kernel

Here a22 is the tangential momentum accommodation coefficient, a2g and are "second-order" coefficients, is the Chapman-Enskog first-order approximation to the viscosity coefficient. Equation (2.68) is, of course, valid for general gas-surface scattering kernels (2.49). Equation (2.68) reduces approximately to... 

Gas-surface scattering kernel R y, v) relates the velocity distribution function of reflected particles/+(v) to that of incident ones/ (v)... 

Determination of the gas-surface scattering kernel from two-photon evanescent-volume-wave fluorescence spectra. Phys. Rev. A, 67 012901-1 - 8. 

A simple model for gas-surface scattering, proposed by Maxwell, can be represented by the kernel... 

To give an idea how does the gas-surface interaction affect the flow rate, some values of Gp for the CL scattering kernel obtained in [13] are given in Table 2. In all regimes the influence of the energy accommodation coefficient an on the flow rate is weak, while the momentum accommodation coefficient at affects significantly the flow rate in the transition S = 1) and near the free molecular S = 0.01) regimes. 

The scattering kernel is a fundamental quantity summarizing the basic information on the gas-surface interaction. It is indirectly contained in the velocity distribution function of the atomic flux departing from the surface (Eq. (2.158)). Therefore, the atoms "remember" how they have been scattered by the surface as long as interatomic collisions in the gas do not destroy this information. This destruction happens at distances of the order of the mean free path from the surface. The corresponding gas slab nearby the surface is called the Knudsen layer. 

Scattering kernel The kernel in the integral equation which relates the velocity distribution function of the gas atoms scattered by the surface to that of the atoms arriving at the surface. 

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