Generation and properties of dark solitons are studied in detail by means of numerical simulation of quasi one-dimensional heteronuclear two-component Bose-Einstein condensates in syntonic potential. Dark solitons are only induced in one of the condensate components by modulational instability with instantaneous conversion of repulsive interspecies interaction to attraction. Solitons pass through each other periodically in syntonie potential. In addition, the number of dark solitons is affiliated with ratio of particle mass and ratio of particles numbers.

The focal dimension of the X-ray source with microbeam is in proportion to the size of the e-beam focused on the target surface. The finite difference method is utilized to calculate the distribution of the electrical-field intensity. The track of the electron-beam is traced by using the Runge-Kutta method within the whole symmetrical system. As a result, the diameter of the electron beam focus is 0.6-1.0μm while the total high brightness emission of the LaB₆ crystal cathode is 0.06-0.3mA.