Bunch of electrons

The synchrotron was developed by elementary particle physics in order to accelerate electrons, positrons, protons and other particles. It consists of a ring with a diameter of about a few meters up to more than 100 m in which a vacuum of 10 mbar can be sustained and to which strong electric and magnetic fields can be applied (see Fig. 1). A bunch of electrons or positrons is first accelerated in a linear accelerator to an energy usually lying between 40 MeV and 380 MeV. 

Harmonic generation of radiation via insertion devices promises to have important applications in photophysics and photochemistry. The basic physical principles were discussed in section 3.3 and the conditions schematized in fig. 8. Spatial bunching of electrons, as described in previous sections, serves not only to create coherent radiation but also to enhance the higher Fourier components in the emitted radiation. 

This is sort of the opposite, because the bar is negative and the protons can t move (only electrons can move). Electrons are pushed away from the bar towards the grounded side of the disk. Then there are a bunch of electrons on the opposite side of the disk. They want to be neutralized, so then the electrons go into the ground, leaving the disk with a positive charge."... 

These bunches of electrons wiU induce alternating current flow in the metal walls of the catcher cavity as they pass through the catcher gap. The output cavity wiU have large oscillating currents generated in its walls. These currents cause electric fields to exist, at the radio frequency, within the output cavity. These electric fields can be coupled from the cavity (to output waveguide, or coaxial transmission hnes) resulting in the RF output power from the tube. 

One other characteristic of synchrotron radiation can be used in spectroscopic studies. If just one bunch of electrons circulates round the ring, the output radiation consists of pulses, a few hundred picoseconds in length, separated by a few hundred nanoseconds. Thus time-dependent studies of short-lived species are possible and given the wide range of energies that are output, all sorts of sophisticated multiple resonance experiments are also feasible. 

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