Author: Rees, D.
Paper Title Page
MOP106016 High Power RF Requirements for Driving Discontinuous Bunch Trains in the MaRIE Linac 320
 
  • J.T. Bradley III, D. Rees, A. Scheinker, R.L. Sheffield
    LANL, Los Alamos, New Mexico, USA
 
  Funding: Work supported by the US Department of Energy.
The MaRIE project will use a superconducting linac to provide 12 GeV electron bunches to drive an X-ray FEL and to do electron radiography. Dynamic experiments planned for MaRIE require that the linac produce a series of micropulses that can be irregularly spaced within the macropulse, and these patterns can change from macropulse to macropulse. Irregular pulse structures create a challenge to optimizing the design of the RF and cryogenic systems. General formulas for cavities with beam loading can overestimate the power required for our irregular beam macropulse. The differing beam energy variations allowed for the XFEL and eRad micropulses produce cavity voltage control requirements that also vary within the macropulse. The RF pulse driving the cavities can be tailored to meet the needs of that particular beam macropulse because the macropulse structure is known before the pulse starts. We will derive a toolkit that can be used to determine the required RF power waveforms for arbitrary macropulse structures. We will also examine how the irregular RF power waveforms can impact RF and cryogenic system cost tradeoffs.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106016  
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TUPLR046 Design, Fabrication, Installation and Operation of New 201 MHz RF Systems at LANSCE 564
 
  • J.T.M. Lyles, W.C. Barkley, R.E. Bratton, M.S. Prokop, D. Rees
    LANL, Los Alamos, New Mexico, USA
 
  Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396.
The LANSCE RM project has restored the proton linac to high power capability after the RF power tube manufacturer could no longer provide devices that consistently met the high average power requirement. Diacrodes® now supply RF power to three of the four DTL tanks. These tetrodes reuse the existing infrastructure including water-cooling systems, coaxial transmission lines, high voltage power supplies and capacitor banks. Each final power amplifier system uses a combined pair of LANL-designed cavity amplifiers using the TH628L Diacrode® to produce up to 3.5 MW peak and 420 kW of mean power. A new intermediate power amplifier was developed using a TH781 tetrode. These amplifiers are the first production of new high power 200 MHz RF sources at accelerators in three decades. Design and prototype testing of the high power stages was completed in 2012, with commercialization following in 2013. Each installation was accomplished during a 4 to 5 month beam outage each year staring in 2014. Simultaneously, a new digital low-level RF control system was designed and tested, and placed into operation this year, meeting the stringent field control requirements for the linac. The rapid-paced installation project changed over from old to new RF systems while minimizing beam downtime to the user facility schedule.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR046  
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