A survey of the current status on sputtering or erosion of solids induced by particle bombardment is given. It is pointed out that general features of the ion-induced sputtering of monatomic solids can be explained by assuming that the collision cascades of knocked-on atoms cause the sputtering. The derivation of the Sigmund theory based on collision cascades is explained in detail. Then discussions are made on the extent of the applicability of the theory and on the modification of the theory necessary to explain recent experimental results. The sputtering of alloys and compounds are shown to be not understood satisfactorily and the relevant experimental results are critically surveyed. It is also pointed out that electronic excitation in insulating solids causes sputtering and the recent studies on sputtering of alkali halides are discussed.
Swrtching of an electrical signal can be performed with picosecond time precision by utilizing the photoconductivity of a silicon single crystal. We have tested various properties of the silicon switch which we have fabricated. Prepulse energy ratio has been measured detecting the main optical pulse from a mode-locked pulse train. Due to the high sensitivity and fast time response of silicon, we could reliably measure small prepulse energy ratio of the order of 10-9. This article reports the principle and detailed properties of a silicon switch.
It has been confirmed by experiments that the relation between the position of the centoroid and the tractive force of ordinary vehicles, having front and rear wheels and being pulled on a soft ground, is shown by a downward convex curve. If it is possible to keep the position of the centroid of a vehicle in the position where tractive force takes the smallest value, namely, the optimum position of the centroid, by moving the load longitudinally on the vehicle, it will form an effective means for saving energy. The authors have developed a model vehicle capable of searching for the optimum position of the centroid automatically and of keeping the centroid in that position. This model vehicle is featured by having a load carrier capable of moving longitudinally and a control device for searching for the optimum position of the centroid.
The formulas of total, normal and tangential energy distributions of field emission electron beams emitted from a superconducting cathode are derived. Their numerical examples for Ta are also given. It is shown that whether the cathode is in the superconducting or the normal state, there is practically no difference in the two cases in the energy distributions of electron beams, except for the detailed distributions in the neighbourhood of the Fermi level.
An apparatus was constructed for measuring the non-contact ratio in sliding contact. By its use, non-contact ratios were measured under various sliding conditions. Certain results show that the non-contact ratio increases with increase of sliding velocity and easily exceeds 75% under ordinary sliding condition. Other results indicate that the non-contact ratio has a marked influence on the wear of sintered-metal and copper during the passage of an electric current. These experi-mental results show that the non-contact ratio is an effective parameter in characterizing sliding contact phenomena.
In this article, brief reviews are given on the recent development in studies of the surface properties of some transition metal carbides. The presence of carbon atoms on the surface reduces the ability of the surface to react with various gases. The chemisorption properties of carburized W(001) surface and TiC(001) surface are much similar to those of Pt or Ag metals, but not to Ti and W metals. On the TiC(001) surface, oxygen atoms are preferentially chemisorbed on the carbon sites at the topmost layer, which seems to be responsible for the inactive oronerties of carbide surfaces.
The molecular design of organic charge transfer complexes, having high electric conduc-tivity, and the synthesis and growth of the crystals are reviewed. The metallic conductivity and the organic superconductivity, which was discovered recently, are described, laying emphasis on unusual characteristics.