6,960 research outputs found
An EPROM-based function generator
A circuit is described to produce arbitrary time-dependent voltage functions derived from digital information stored in EPROMs. While this circuit is designed to be used as a modulator of the microwave pump source or a solid state low noise maser, it can be readily adapted for other applications
Towards Zeptosecond-Scale Pulses from X-Ray Free-Electron Lasers
The short wavelength and high peak power of the present generation of
free-electron lasers (FELs) opens the possibility of ultra-short pulses even
surpassing the present (tens to hundreds of attoseconds) capabilities of other
light sources - but only if x-ray FELs can be made to generate pulses
consisting of just a few optical cycles. For hard x-ray operation (~0.1nm),
this corresponds to durations of approximately a single attosecond, and below
into the zeptosecond scale. This talk will describe a novel method to generate
trains of few-cycle pulses, at GW peak powers, from existing x-ray FEL
facilities by using a relatively short 'afterburner'. Such pulses would enhance
research opportunity in atomic dynamics and push capability towards the
investigation of electronic-nuclear and nuclear dynamics. The corresponding
multi-colour spectral output, with a bandwidth envelope increased by up to two
orders of magnitudes over SASE, also has potential applications.Comment: Submitted to 35th International Free Electron Laser Conference, New
York, 201
Investigation of a 2-Colour Undulator FEL Using Puffin
Initial studies of a 2-colour FEL amplifier using one monoenergetic electron
beam are presented. The interaction is modelled using the unaveraged, broadband
FEL code Puffin. A series of undulator modules are tuned to generate two
resonant frequencies along the FEL interaction and a self-consistent 2-colour
FEL interaction at widely spaced non-harmonic wavelengths at 1nm and 2.4nm is
demonstrated.Comment: Submitted to The 35th International Free-Electron Laser Conference,
Manhattan, New York (2013
A wide bandwidth free-electron laser with mode locking using current modulation
A new scheme for mode locking a free-electron laser (FEL) amplifier is proposed based on electron beam current modulation. It is found that certain properties of the original concept (Thompson and McNeil 2008 Phys. Rev. Lett. 100 203901), based on the energy modulation of electrons, are improved, including the spectral brightness of the source and the purity of the series of short pulses. Numerical comparisons are made between the new and old schemes and between a mode-locked FEL and a self-amplified spontaneous emission FEL. Illustrative examples using a hypothetical mode-locked FEL amplifier are provided. The ability to generate intense coherent radiation with a large bandwidth is demonstrated
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