SEISMIC PERFORMANCE EVALUATION OF SUSPENSION BRIDGES

Apparatus for producing X-rays from an electric insulator. Two electrodes are disposed to contact the electric insulator. One electrode has a larger contact area with the insulator than that of the other. When a high D.C. or A.C. voltage is applied across the electrodes, the electric field becomes stronger in the portion of the insulator near the contact section with the small electrode, resulting in the production of X-rays from the vicinity of the contact section of the insulator with the small electrode.