Patent attributes
An electromagnetic wave generating device includes: a hollow annular vacuum chamber; an electron gun; an electromagnet configured with a pair of discoid combinations in which a cylindrical accelerating magnet pole and an annular focusing magnet pole are arranged in this order from the inner side to the outer side of the combinations, and are disposed symmetrically and concentrically with each other on both sides of the chamber and coaxially with the center axis of the chamber, and a return yoke disposed outside both accelerating and focusing magnet poles and the chamber; accelerating coils wound around the accelerating magnet poles, for exciting the poles; and focusing coils wound around the focusing magnet poles, for exciting the poles; wherein a through hole is formed at the center of the accelerating magnet pole so that power supply wires connecting the accelerating coils to an accelerating power supply are led out through the hole.