ELECTRON GUN AND MAGNETIC CIRCUIT FOR AN IMPROVED THZ ELECTROMAGNETIC SOURCE

摘要

The present invention provides an enhanced THz electromagnetic source structure achieving a very high aspect ratio of 500 to 1 of electron beam width to electron beam thickness of the electron beam moving in the direction across the grating structure while maintaining its cross-section. The structure comprises a magnetic circuit providing a unique low magnetic field slot placed in a steel core for the placement of an electron gun, thus allowing the electron beam to be focused without the interaction of a magnetic field while still supporting a high magnetic field in the grating region. Additionally, the structure comprises an electrostatic shield preventing potential difference between the anode voltage and the grounded steel core from affecting the focusing of the electron beam.