Both the laser-plasma wakefield accelerator (LWFA) and X-ray phase-contrast imaging (XPCi) are promising technologies that are attracting the attention of the scientific community. Conventional X-ray absorption imaging cannot be used as a means of imaging biological material because of low contrast. XPCi overcomes this limitation by exploiting the variation of the refraction index of materials....

A new scheme for the two-dimensional cooling of ion beams in storage rings is suggested in which ions interact with a counterpropagating broad-band laser beam. The interaction region in the direction of the ion movement is much less then the wavelength of the ion betatron oscillations. The laser beam in the orbit plane has sharp flat edge directed to the ion beam and the width of the laser beam...

A new optics has been designed for Sirius with improved betatron function matching in the 6 meter-long low beta straight sections for insertion devices. Both horizontal and vertical betatron functions are set to 1.5 m in the center of the section, improving the matching of the electron and undulator photon beams. In addition, the horizontal beam stay clear has also been reduced allowing for sma...

We present the first measurements of the angular dependence of the betatron x-ray spectrum produced by electrons inside the cavity of a laser-wakefield accelerator. Electrons accelerated up to 300 MeV energies produce a beam of broadband, forward-directed betatron x-ray radiation extending up to 80 keV. The angular resolved spectrum from an image plate-based spectrometer with differential filte...

Dispersion relations are derived to determine the growth rate, dominant wavelength, and group velocity of disturbances caused by the beam breakup instability. Considerations include weak and strong focusing, x-y coupling in solenoidal transport, the spacing of accelerator cavities, and periodically pulsed beams. Beam breakup growth is minimum when the cavity spacing equals an integral number of...

Observations of the beam-beam interaction at SPEAR, CESR, PETRA and PEP are discussed. They are sufficiently similar that a simple prescription can be formulated to describe the behavior of the luminosity as a function of current including the peak values. With this prescription the interpretation of various methods of increasing the luminosity, such as the reduction of the vertical betatron fu...

We present investigations on beam instabilities that have been observed at 2.0 GeV and 2.5 GeV in the PLS storage ring. Stored beam currents of 2.0 GeV in the ring has been mainly limited by coupled-bunch instabilities. We have investigated dependences of the coupled-bunch instabilities on betatron tune, chromaticity and rf cavity temperatures at 2.0 GeV. 450 mA beam could be stored at 2.0 GeV....

Each of the four fractional betatron tunes of RHIC (two planes, two rings) is measured with a transverse beam kicker and dedicated beam position monitor (BPM). A 15kV pulse is generated by a fast FET switch, passed through a stripline kicker, attenuated, and returned to the instrumentation control room (ICR) for monitoring. When pulsed at 3kV, the four-meter long kicker gives a gold beam at inj...

Abstract Magnetic flux ropes or magnetic islands are important structures responsible for electron acceleration and energy conversion during turbulent reconnection. However, the evolution of corresponding process still remain open questions. In this paper, we present a comparative study observed by Magnetospheric Multiscale mission in outflow region an example reconnection Earth's magnetotail. ...

By exploiting analogical optical modeling of the radiation emitted by ultrarelativistic electrons undergoing betatron oscillations, we demonstrate peculiar properties of the spatial coherence through an interferometric method reminiscent of the classical Young's double slit experiment. The expected effects due to the curved trajectory and the broadband emission are accurately reproduced. We sho...