The temperature of a substrate, while the covering is drawing on it’s surface, страница 10

In order to to show these laws more evidently, we shall consider below area of collisions of firm spheres in two various intervals of energies. In figure 5.1 curves of dependences of the dispersion coefficient S on the energy of ions _Еi changing in limits approximately from 50 up to 250 eV are submitted. These dependences have been received by Koedamm [78] at an irradiation of a silver target on a normal to its surface by ions Not +, Ne +, Ar +, Kg +. In case of an irradiation ions Аг + and Kg + function S (Е) is approximately linear in area of energies 150 … 250 eV and approximately square-law at lower energies of  ions (~50 … 150 eV). For ions Ne + functionS (Е) is approximately linear in the field of 80 … 180 eV. At higher energies the curve, apparently, passes in area of saturation. In case of an irradiation ions He + functionS (Е) is linear in area энергий 100 … 250 eV. Absolute values S for ions of various inert gases (He +, Ne +, Kg +) find out natural behaviour, that is size S grows with increase in weight and nuclear number of a bombarding ion. However in case of an irradiation ions Аг + and Kg + the curve for Аг + lays above, than for Kg +, notwithstanding what Kr has the big weight and higher nuclear number.

Similar dependence has been found out at dispersion of various targets by ions Аг + and Хе + (figure 5.2 and 5.3).

Figure 5.1 Dependence of the dispersion coefficient on energy of ions of the inert gases bombarding a silver target.

Figure 5.2 Dependence of the dispersion coefficient on energy of ions of the argon bombarding various targets.

Figure 5.3 Dependence of the dispersion coefficient on energy of Xe ions, bombarding various targets.

Above mentioned results show, that in the field of low energies of ions there is a complex dependence of the dispersion coefficient on energy of ions. Different authors offered various approximations of dependence of the dispersion coefficient S from energy of ions _Еi. However any of existing theories of dispersion, which can be applied in this area of energies, does not allow to reproduce all experimental results correctly. Thus, any of prelegends concerning behaviour of function S(Е) in this area of energies is not exact generally.

It has been noticed, that if to present factor of dispersion as a function of nuclear number of a material of a target (at an irradiation of targets ions Аг + with energy 400 eV), there will be an interesting law (figure 5.4) [47].

Within the limits of the given period of system of elements the factor of dispersion grows in process of filling nuclear d-environments, and Си, Ag and Au have the highest dispersion coefficients. This conclusion remains in force and at an irradiation of targets by ions Ar +, Ne +, Hg +. For all three cases unique exception makes a target from Cr for which the dispersion coefficient is higher, than for cobalt.

Figure 5.4 Dependence of the dispersion coefficient on nuclear number of a material of the target, received at an irradiation of various targets by ions of argon with energy 400 eV [47].

Fig. 5.5 The dispersion coefficient of iron (on the right) and copper (at the left) depending on energy of ions of inert gases [78].

In table 5.2 values of factors of dispersion of various materials for ions of inert gases with energy 100 … 600 eV are resulted. In figure 5.5 dependences of factors of dispersion of iron and copper on energy of ions of inert gases are submitted.

On the basis of the collected data it is possible to draw a conclusion, that character of all dependences has a general view - with growth of energy of bombarding ions the factor of dispersion increases. The given statement is fair in a considered range of energies (300 … 1000 eV), as at great values _Еі (more than 20 keV) there can be a reduction of factor of dispersion. Also the dispersion coefficient in a considered range looks like close to linear dependence in one cases, in others looks like close to square-law function.