| 摘要 |
<p>An electron beam deflection structure (10) of the traveling wave type effectively cancels the longitudinal voltage gradients and the associated electron beam defocusing that are characteristic of such deflection structures. The deflection structure comprises a first helical coil member (48) and a second helical coil member (50) that are coaxial with the longitudinal axis (26) of the tube. Each of the coil members has wide and narrow segments which alternate along the length of the coil in sequence with the turns of the coil. The first coil member has its wide segments (92a) positioned on the bottom and its narrow segment (92b) on top of the coil member. The second coil member has its wide segments (94a) positioned on top and its narrow segments (94b) positioned on the bottom of the coil member. The narrow segments from one of the coil members are interleaved with the wide segments from the other coil member. A pair of linear arrays (100) and (102) are thereby formed which are positioned above and below the electron beam path and comprise wide and narrow segments from different coil members. Differential voltage signals of opposite polarity are applied to the first and second coil members of the deflection structure. Longitudinal voltage gradients along the wide segments are compensated by substantially equal but opposite voltage gradients on the narrow segments, thereby effectively canceling the longitudinal voltage gradients and eliminating any defocusing of the electron beam that the voltage gradients would cause.</p> |
