GB888913A - Radio frequency parametric amplifier - Google Patents

Abstract

888,913. Space charge wave tubes. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Oct. 19, 1960 [Oct. 28, 1959], No. 36613/59. Class 39(1) A parametric amplifier with an input signal coupling section to make the electrons of the beam follow helical paths, an amplifying pump section with an axial magnetic field and a multiple quadrupole electrostatic field which increases the rotational electron energy and an output signal coupling section, successive quadrupole fields being so orientated that the changes in rotational velocity of the electrons are cumulative. The pump has four hyperbolic electrodes. Either (a) there is no axial bias, the beam slowing up as the rotational velocity is increased. All the positive pairs and all the negative pairs of electrodes are connected together and to external leads (b) axial bias, constant axial velocity and pitch of electrons, the rotational velocity increasing or (c) axial accelerating bias the rotational and axial velocities increasing. The quadrupole pitch increases to maintain synchronism. In Fig. 2 rings each having 2 tongues 6, 7 are piled up with intermediate insulating rings to form quadrupoles. Each conductive ring forms the high voltage pair of one quadrupole and the low voltage pair of the next quadrupole. The axial lengths of successive rings increase. Potentials are applied by a potential divider chain outside or inside the envelope. Insulating support rods fit in four locating holes 8, 9, 10, 11. In Fig. 3 the quadrupole electrodes have connections Vo-V 12 from the potential divider chain to reduce the number of connections and to give smaller voltage increments between the quadrupoles than in Fig. 2. Insulating support rods 18, 19, 20, 21 are provided. In general the quadrupole electrodes are “ of a cyclotron period long and in Fig. 2 successive quadrupoles are rotated by 90 degrees. The output is coupled to the fast or slow wave in the latter case it is a slow wave structure. An axial magnetic field focuses the beam and sets up the initial helical motion thereof. The pump structure may alternatively be a four start helix.