| 摘要 |
974,153. Travelling-wave tubes. CSF-COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL. Jan. 2, 1963 [Jan. 11, 1962], No. 207/63. Heading H1D. In a low-noise travelling-wave tube comprising an electron emitting surface 2<SP>1</SP>, a delay line 3 and a collector 4, the electron beam is shaped by an external magnetic field so that over a predetermined portion near the cathode it has a cross-section diameter substantially the same as that of the emitting surface, whilst the diameter along the delay line is smaller than that of the emitting surface. The magnetic field is formed by permanent magnets 5, polepieces 6 and field straighteners 7, which straighteners are disposed closer together along the gun region of the tube than along the delay line region. |
