High-power multimodeX-band rf pulse compression system for future linear colliders

Abstract

We present a multimode X-band rf pulse compression system suitable for a TeV-scale electron-positron linear collider such as the Next Linear Collider (NLC). The NLC main linac operating frequency is 11.424 GHz. A single NLC rf unit is required to produce 400 ns pulses with 475 MW of peak power. Each rf unit should power approximately 5 m of accelerator structures. The rf unit design consists of two 75 MW klystrons and a dual-moded resonant-delay-line pulse compression system that produces a flat output pulse. The pulse compression system components are all overmoded, and most components are designed to operate with two modes. This approach allows high-power-handling capability while maintaining a compact, inexpensive system. We detail the design of this system and present experimental cold test results. We describe the design and performance of various components. The high-power testing of the system is verified using four 50 MW solenoid-focused klystrons run off a common 400 kV solidstate modulator. The system has produced 400 ns rf pulses of greater than 500 MW. We present the layout of our system, which includes a dual-moded transmission waveguide system and a dual-moded resonant line (SLED-II) pulse compression system. We also present data on the processing and operation of this system, which has set high-power records in coherent and phase controlled pulsed rf.

Quasi-Optical 34-GHz Rf Pulse Compressor

“…Since first introduced for SLC, RF pulse compressors with steadily improving parameters have continued to be developed. Most recently, a dual-mode, dual delay line SLED-II type pulse compressor demonstrated 4:1 compression with a peak rf power of >500 MW at X-band [7]. The concepts enshrined in that S-and X-band RF pulse compression work have informed the Ka-band work recounted here.…”

“…The voltage produced by the high-voltage pulse generator (3) was fed to the electrodes of the discharge channels via a set of ballast resistors (4). The radiation from the resonator output was sent to detector (6) via attenuator (5), and then registered with a digital oscilloscope (7). In order to measure the frequency characteristics of the compressor, generator (2) was switched to the regime of frequency sweeping.…”

Few-femtosecond time-resolved measurements of X-ray free-electron lasers

“…A pulse duration of less than 3 fs FWHM at soft X-ray energy has been measured, and the electron trapping in X-ray FELs was experimentally observed in the deep-saturation regime. To further improve the temporal resolution, one can increase the deflecting strength by either adding more deflectors or upgrading the existing power source with rf pulse compression technology [49][50][51] . It is also possible to further optimize the electron beam optics by adding quadrupole magnets.…”

Compton Scattering Sources and Applications at LLNL

“…The T-REX source is described by its key parameters: size (0.01 mm 2 ), divergence (10x6 mrad 2 ), duration (ps), spectrum (15% bandwidth) and intensity (10 5 photons/shot), all of which are summarized by an on-axis peak brightness of 2.5x10 15 photons/mm 2 /mrad 2 /s/0.1% bandwidth at 0.478 MeV. NRF measurements, a promising method for isotopic imaging, assay, and detection, were performed on 7 Li using this source [1].…”