Author: Brennan, N.W.
Paper Title Page
THPPC069 Design, Test and Implementation of New 201.25 MHz Power Amplifier for the LANSCE Linac 3446
 
  • J.T.M. Lyles, Z. Chen, J. Davis, A.C. Naranjo, D. Rees, G. M. Sandoval, Jr.
    LANL, Los Alamos, New Mexico, USA
  • D. Baca, R.E. Bratton, R.D. Summers
    Compa Industries, Inc., Los Alamos, New Mexico, USA
  • N.W. Brennan
    Texas A&M University, College Station, Texas, USA
 
  Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396
A new 201.25 MHz final power amplifier (FPA) has been designed, fabricated, and tested at Los Alamos Neutron Science Center (LANSCE). The prototype FPA has produced 3 MW peak and 250 kW of mean power with 15 dB of power gain and over 60% efficiency. It has been tested for several thousand hours with a load. A Thales TH628 Diacrode® electron tube is key to the performance of the new amplifier. It is configured with a full wavelength output circuit, having the lower main tuner situated ¾λ from the central electron beam region in the tube and the upper slave tuner ¼λ from the same point. The FPA is designed with input and output transmission line cavity circuits, grid decoupling circuits, an adjustable output coupler, DC blocking and RF bypassing capacitors, HOM suppressors, and a cooling system. A pair of production amplifiers are planned to be power-combined for up to 3.6 MW peak power at high duty factor. Three of these combined amplifiers will be installed in place of the original 1968-vintage amplifiers to return LANSCE operation to 12% beam duty factor with higher peak current than presently possible.
 
 
THPPC070 A High Power Test Facility for New 201.25 MHz Power Amplifiers and Components 3449
 
  • J.T.M. Lyles, J. Davis, D. Rees, G. M. Sandoval, Jr., A. Steck, D.J. Vigil
    LANL, Los Alamos, New Mexico, USA
  • D. Baca, R.E. Bratton, R.D. Summers
    Compa Industries, Inc., Los Alamos, New Mexico, USA
  • N.W. Brennan
    Texas A&M University, College Station, Texas, USA
 
  Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396
A new test facility was designed and constructed at Los Alamos Neutron Science Center (LANSCE) for testing a new Thales TH628 Diacrode® final power amplifier and associated driver stages. Anode power requirements for the TH628 are 28 kV DC, with 190 Amperes in millisecond pulses. A 225 uF capacitor bank supplies this current demand, with a crowbar circuit to rapidly discharge 88 kJ of stored energy. Charging current was obtained by re-configuring a 2 MW beam power supply remaining from another project. The power tubes are operated with DC anode voltage, and beam pulsing is done with control grid bias switching at relatively low power. A new Fast Protect and Monitor System was designed to take samples of RF reflected power, anode HV, and various tube currents, with logic outputs to promptly remove high voltages, RF drive and beam pulsing during faults. The entire test system is controlled with a programmable logic controller, for normal startup sequencing, protection against loss of cooling, and operator GUI. This test facility has been used over the past year to test the amplifiers along with high power coaxial components such as hybrid couplers and various water loads.