Pretilt angle measurable by using the conventional crystal rotation method is limited to about 0°–20° and 70°–90°. We propose a method by which we can measure the pretilt angle by using the crystal rotation method even if the pretilt angle is between 20° and 70°. In this method, the determination of a pretilt angle is achieved by finding the rotation angles where transmittances are maximum and minimum in the periodic transmittance characteristics obtained with the variation of rotation angle.

A method for etching field emission tips from Pd-Si-Cu metallic glass wires is described. The field electron emission from these tips is sufficiently stable in the 10-9 Torr region. The emission is confined to a cone of half-angle 0.1 5 rad for a total emission current of about 5 FA.

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Previous relative measurements of the differential cross sections for ionization of neon atoms in collisions with fast sodium atoms have been put on an absolute scale. This was done by measuring the ratio of ions and neutral atoms in a fast mixed (ions and neutrals) sodium beam and by using the well known differential cross section for elastic scattering of sodium ions by neon atoms. The measured ionization cross sections exhibit a steep rise from threshold to a flat maximum between 300 and 400eV.

The problem of possible structures of normal ionizing shock waves is studied. On the basis of the general theory of ionizing shock waves in magnetic fields previously developed (LIBERMAN and VELIKOVICH, 1981~1, b) a similarity solution of the piston problem for an impenetrable piston and a magnetic piston is described and a numerical solution of the non-stationary piston problem is obtained. It is shown that precursor photo-ionization of the neutral gas by the radiation of the shock-heated gas is the dominant factor in shaping normal ionizing shock structures. In particular, it is shown that the strong overheating of atoms and ions in shock fronts is due to the tensor form of Ohm's law in the precursor region. The conditions of formation of type 3 and type 4 shock structures are elucidated together with the limits of applicability of the Chapman-Jouguet hypothesis. The theory is applied to the interpretation of the experimental data on normal ionizing shock waves.