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Title: DEVELOPMENT AND TESTING OF HIGH POWER RF VECTOR MODULATORS*

Abstract

A fan-out RF power distribution system can allow many accelerating cavities to be powered by a single high-power klystron amplifier. High-power vector modulators can perform independent control of amplitudes and phases of RF voltages at the cavities without changing the klystron signal. A prototype highpower RF vector modulator employing a quadrature hybrid and two ferrite phase shifters in coaxial TEM transmission lines has been built and tested for 402.5 MHz. RF properties of the design and results of high power testing are presented.

Authors:
 [1];  [1];  [2];  [1];  [1];  [1];  [1]
  1. ORNL
  2. FNAL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
931838
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: PAC 2007, Albuquerque, NM, USA, 20070624, 20070629
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; RF SYSTEMS; AMPLIFIERS; CAVITIES; DESIGN; KLYSTRONS; MODULATION; QUADRATURES; TESTING; SPALLATION; NEUTRON SOURCES

Citation Formats

Kang, Yoon W, Wilson, Joshua L, Champion, Mark, Hardek, Thomas W, Kim, Sang-Ho, McCarthy, Mike, and Vassioutchenko, Alexandre V. DEVELOPMENT AND TESTING OF HIGH POWER RF VECTOR MODULATORS*. United States: N. p., 2007. Web.
Kang, Yoon W, Wilson, Joshua L, Champion, Mark, Hardek, Thomas W, Kim, Sang-Ho, McCarthy, Mike, & Vassioutchenko, Alexandre V. DEVELOPMENT AND TESTING OF HIGH POWER RF VECTOR MODULATORS*. United States.
Kang, Yoon W, Wilson, Joshua L, Champion, Mark, Hardek, Thomas W, Kim, Sang-Ho, McCarthy, Mike, and Vassioutchenko, Alexandre V. Mon . "DEVELOPMENT AND TESTING OF HIGH POWER RF VECTOR MODULATORS*". United States. doi:.
@article{osti_931838,
title = {DEVELOPMENT AND TESTING OF HIGH POWER RF VECTOR MODULATORS*},
author = {Kang, Yoon W and Wilson, Joshua L and Champion, Mark and Hardek, Thomas W and Kim, Sang-Ho and McCarthy, Mike and Vassioutchenko, Alexandre V},
abstractNote = {A fan-out RF power distribution system can allow many accelerating cavities to be powered by a single high-power klystron amplifier. High-power vector modulators can perform independent control of amplitudes and phases of RF voltages at the cavities without changing the klystron signal. A prototype highpower RF vector modulator employing a quadrature hybrid and two ferrite phase shifters in coaxial TEM transmission lines has been built and tested for 402.5 MHz. RF properties of the design and results of high power testing are presented.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Conference:
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  • One of the goals of the low energy 60 MeV section of the HINS H{sup -} linac [1] is to demonstrate that a total of {approx}40 RF cavities can be powered by a single 2.5 MW, 325 MHz klystron. This requires individual vector modulators at the input of each RF cavity to independently adjust the amplitude and phase of the RF input signal during the 3.5 ms RF pulse. Two versions of vector modulators have been developed; a 500 kW device for the radiofrequency quadrupole (RFQ) and a 75 kW modulator for the RF cavities. High power tests showing themore » vector modulator phase and amplitude responses will be presented.« less
  • In the rf-driven free-electron laser (FEL) at the Los Alamos National Laboratory, there are two pulsed-power rf modulators as sources for two tandem, side-coupled 20-MeV linear accelerators. The rf power used to control the cavity fields is supplied by two 5.5-MW modulating anode klystrons operating at a center frequency of 1300.2 MHz. The modulation of the 125 kV klystron is achieved by using a triode switch tube that provides a pulse width up to 300 ..mu..s and a pulse repetition rate up to 10 Hz. This paper describes the present configuration of these two duplicate systems and presents plans formore » meeting the requirements of future rf FEL experiments at Los Alamos. 12 refs., 5 figs.« less
  • SLAC is committed to developing an X-band source capable of producing 100 Megawatt, 1 microsecond pulses to power the next linear collider. The first experience encountered at SLAC in the X-Band Regime above a few Megawatts was in the relativistic klystron program in cooperation with LLNL and LBL. About 280 MW had been transmitted through a variety of waveguide components but at very short pulse widths ({approximately}40 nanseconds) and very low pulse repetition rates. The likelihood of high peak power rf breakdown in most X-band components and especially rf windows increases as the rf pulse length becomes longer. Testing componentsmore » at peak power levels above that at which they are expected to reliably perform is essential in a development program.« less
  • SLAC is committed to developing an X-band source capable of producing 100 Megawatt, 1 microsecond pulses to power the next linear collider. The first experience encountered at SLAC in the X-Band Regime above a few Megawatts was in the relativistic klystron program in cooperation with LLNL and LBL. About 280 MW had been transmitted through a variety of waveguide components but at very short pulse widths ({approximately}40 nanseconds) and very low pulse repetition rates. The likelihood of high peak power rf breakdown in most X-band components and especially rf windows increases as the rf pulse length becomes longer. Testing componentsmore » at peak power levels above that at which they are expected to reliably perform is essential in a development program.« less
  • A 352-MHz fast-ferrite rf cavity tuner, manufactured by Advanced Ferrite Technology, was high-power tested on a single-cell copper rf cavity at the Advanced Photon Source. These tests measured the fast-ferrite tuner performance in terms of power handling capability, tuning bandwidth, tuning speed, stability, and rf losses. The test system comprises a single-cell copper rf cavity fitted with two identical coupling loops, one for input rf power and the other for coupling the fast-ferrite tuner to the cavity fields. The fast-ferrite tuner rf circuit consists of a cavity coupling loop, a 6-1/8-inch EIA coaxial line system with directional couplers, and anmore » adjustable 360{sup o} mechanical phase shifter in series with the fast-ferrite tuner. A bipolar DC bias supply, controlled by a low-level rf cavity tuning loop consisting of an rf phase detector and a PID amplifier, is used to provide a variable bias current to the tuner ferrite material to maintain the test cavity at resonance. Losses in the fast-ferrite tuner are calculated from cooling water calorimetry. Test data will be presented.« less