| 摘要 |
PURPOSE:To make it possible to ignore the influence in the boundary face between an electrode metal and insulating materials and evaluate the insulation of various kinds of insulating material, by charging accelerated electrons to insulating materials from the external or irradiating insulating materials with them. CONSTITUTION:The electron beam having a very short pulse duration which is accelerated by a negative voltage of a DC high voltage power source 208 and is controlled by a grid pulser 209 is condensed to a very small diameter by an electromagnetic focusing coil 205, and the surface of insulating materials 101 placed in a vacuum body 201 is irradiated with this electron beam. The irradiated electron beam is bound in a minute region near the surface of insulating materials 101 and becomes the space charge; and when the electric field generated by this space charge exceeds a certain limit value, a local breakdown is caused. This local breakdown is observed from the external through a quartz window 206 by a microscope 205. Since the electron beam is controlled to have a very short pulse duration by the grid pulser 209, the insulation test of not thermal breakdown but purely electronic breakdown of insulating materials 101 is performed. Further, since the acceleration energy of electrons is controlled freely by the DC high voltage power source 208, the influence of charged energy upon the dielectric breakdown of insulating materials 101 is detected. |
