9 research outputs found
Relativistic particle motion of a charge including the radiation reaction
The problem of the electromagnetic radiation of an accelerated charged particle is one of the
most controversial issues in Physics since the beginning of the last century representing one of
the most popular unsolved problems of the Modern Physics. Different equations of motion for
a point charge including the electromagnetic radiation emitted have been proposed throughout
history, but all these expressions show some limitations. An equation based on the principle of
conservation of energy is proposed for the ultra-relativistic motion. Different examples are
analyzed showing that the energy lost by the charge agrees with the relativistic generalization
of the Larmor formula. This proposed equation has been compared with the Landau-Lifshitz
equation obtaining a good agreement in the range of application of the Landau-Lifshitz formula.
Finally, it is discussed a possible variation of the typical relativistic particle integrators (e.g. Boris,
Vay or Higuera-Cary methods) in order to include the radiation reaction
Study of the RF pulse heating phenomenon in high gradient accelerating devices by means of analytical approximations
The main objective of this work is to present a
simple method, based on analytical expressions, for obtaining
a quick approximation of the temperature rise due to the Joule
effect inside the metallic walls of an RF accelerating device. This
proposal relies on solving the 1D heat-transfer equation for a
thick wall, where the heat sources inside the wall are the ohmic
losses produced by the RF electromagnetic fields penetrating
the metal with finite electrical conductivity. Furthermore, it is
discussed how the theoretical expressions of this method can be
applied to obtain an approximation to the temperature increase
in realistic 3D RF accelerating structures, taking as an example
the cavity of an RF electron gun. These theoretical results have
been benchmarked with numerical simulations carried out with
commercial finite-element method codes, finding good agreement
among them
Two-dimensional simulation of the electron transport in a photomultiplier tube
Photomultiplier tubes are widely used in experimental physics because they convert small light
signals into a measurable electric current. Although their working principle is well known, it is
very difficult to find simulations of the electron transport in these devices. For this reason, the
electron transport in the Hamamatsu R13408-100 photomultiplier tube has been simulated in
2D. The software SUPERFISH is used for calculating the electrostatic fields and the Boris method
for the effective electron dynamics. The secondary electron emission in the dynodes is
implemented using an effective electron model and the modified Vaughan’s model. Some
figures of merit for photomultiplier tubes (e.g. the gain, the electron transit time or the transit
time spread) in function of the supply voltage and an external magnetic field have been studied
obtaining a good qualitative accordance with the Hamamatsu datasheet. In further studies, we
are going to compare our simulations with experimental measurements
X-band RF photoinjector design for the CompactLight project
RF photoinjectors have been under development for several decades to provide the high-brightness electron beams required for X-ray Free Electron Lasers. This paper proposes a photoinjector design that meets the Horizon 2020 CompactLight design study requirements. It consists of a 5.6-cell, X-band (12 GHz) RF gun, an emittance-compensating solenoid and two X-band traveling-wave structures that accelerate the beam out of the space-charge-dominated regime. The RF gun is intended to operate with a cathode gradient of 200 MV/m, and the TW structures at a gradient of 65 MV/m. The shape of the gun cavity cells was optimized to reduce the peak electric surface field. An assessment of the gun RF breakdown likelihood is presented as is a multipacting analysis for the gun coaxial coupler. RF pulse heating on the gun inner surfaces is also evaluated and beam dynamics simulations of the 100MeV photoinjector are summarized
Spectrum/Space Switching and Multi-Terabit Transmission in Agile Optical Metro Networks
An SDN-enabled modular photonic system architecture, including VCSEL-based bandwidth/bitrate variable transceivers, for multi-terabit capacity transmission and agile spectrum/space switching in optical metro networks is presented, providing the proposed technological solutions, programmability aspects and preliminary assessment