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Title: Solid State Power Amplifier for 805 MegaHertz at the Los Alamos Neutron Science Center

Abstract

Particle accelerators for protons, electrons, and other ion species often use high-power vacuum tubes for RF amplification, due to the high RF power requirements to accelerate these particles with high beam currents. The final power amplifier stages driving large accelerators are unable to be converted to solid-state devices with the present technology. In some instances, radiation levels preclude the use of transistors near beamlines. Work is being done worldwide to replace the RF power stages under about ten kilowatts CW with transistor amplifiers, due to the lower maintenance costs and obsolescence of power tubes in these ranges. This is especially practical where the stages drive fifty Ohm impedance and are not located in high radiation zones. The authors are doing this at the Los Alamos Neutron Science Center (LANSCE) proton linear accelerator (linac) in New Mexico. They replaced a physically-large air-cooled UHF power amplifier using a tetrode electron tube with a compact water-cooled unit based on modular amplifier pallets developed at LANSCE. Each module uses eight push-pull bipolar power transistor pairs operated in class AB. Four pallets can easily provide up to 2,800 watts of continuous RF at 805 MHz. A radial splitter and combiner parallels the modules. This amplifiermore » has proven to be completely reliable after over 10,000 hours of operation without failure. A second unit was constructed and installed for redundancy, and the old tetrode system was removed in 1998. The compact packaging for cooling, DC power, impedance matching, RF interconnection, and power combining met the electrical and mechanical requirements. CRT display of individual collector currents and RF levels is made possible with built-in samplers and a VXI data acquisition unit.« less

Authors:
;
Publication Date:
Research Org.:
Los Alamos National Lab., NM (US)
Sponsoring Org.:
USDOE Office of Defense Programs (DP) (US)
OSTI Identifier:
759413
Report Number(s):
LA-UR-98-4554
TRN: US0004506
DOE Contract Number:  
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: RF Design Expo, San Jose, CA (US), 10/19/1998--10/21/1998; Other Information: PBD: 19 Oct 1998
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; DESIGN; LINEAR ACCELERATORS; OPERATION; POWER AMPLIFIERS; TRANSISTOR AMPLIFIERS; RELIABILITY

Citation Formats

Davis, J.L., and Lyles, J.T.M. Solid State Power Amplifier for 805 MegaHertz at the Los Alamos Neutron Science Center. United States: N. p., 1998. Web.
Davis, J.L., & Lyles, J.T.M. Solid State Power Amplifier for 805 MegaHertz at the Los Alamos Neutron Science Center. United States.
Davis, J.L., and Lyles, J.T.M. Mon . "Solid State Power Amplifier for 805 MegaHertz at the Los Alamos Neutron Science Center". United States. https://www.osti.gov/servlets/purl/759413.
@article{osti_759413,
title = {Solid State Power Amplifier for 805 MegaHertz at the Los Alamos Neutron Science Center},
author = {Davis, J.L. and Lyles, J.T.M.},
abstractNote = {Particle accelerators for protons, electrons, and other ion species often use high-power vacuum tubes for RF amplification, due to the high RF power requirements to accelerate these particles with high beam currents. The final power amplifier stages driving large accelerators are unable to be converted to solid-state devices with the present technology. In some instances, radiation levels preclude the use of transistors near beamlines. Work is being done worldwide to replace the RF power stages under about ten kilowatts CW with transistor amplifiers, due to the lower maintenance costs and obsolescence of power tubes in these ranges. This is especially practical where the stages drive fifty Ohm impedance and are not located in high radiation zones. The authors are doing this at the Los Alamos Neutron Science Center (LANSCE) proton linear accelerator (linac) in New Mexico. They replaced a physically-large air-cooled UHF power amplifier using a tetrode electron tube with a compact water-cooled unit based on modular amplifier pallets developed at LANSCE. Each module uses eight push-pull bipolar power transistor pairs operated in class AB. Four pallets can easily provide up to 2,800 watts of continuous RF at 805 MHz. A radial splitter and combiner parallels the modules. This amplifier has proven to be completely reliable after over 10,000 hours of operation without failure. A second unit was constructed and installed for redundancy, and the old tetrode system was removed in 1998. The compact packaging for cooling, DC power, impedance matching, RF interconnection, and power combining met the electrical and mechanical requirements. CRT display of individual collector currents and RF levels is made possible with built-in samplers and a VXI data acquisition unit.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1998},
month = {10}
}

Conference:
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