Electron beam relativistic

Free-Electron Lasers. The free-electron laser (EEL) directly converts the kinetic energy of a relativistic electron beam into light (45,46). Relativistic electron beams have velocities that approach the speed of light. The active medium is a beam of free electrons. The EEL, a specialized device having probably limited appHcations, is a novel type of laser with high tunabiHty and potentially high power and efficiency. 

Other experiments reported the production of high-energy electrons with a similar set-up, and showed the suitability of such relativistic bunches for nuclear activation techniques. It has been showed that nuclear reactions could be efficiently triggered by electrons from thin CH foil targets [69], and also that nuclear reactions can be a useful tool to characterize the electron beam accelerated with similar targets [70]. This point will be further developed in Sect. 8.4. 

A further important property of synchrotron radiation concerns its polarization characteristics. The radiation is completely polarized, and the kind of polarization depends on the direction of the circulating electron beam as well as on the direction of photon emission. In order to understand these polarization properties, it is useful to recall the result for the emission of electromagnetic radiation from an electron moving with non-relativistic velocity in a circle the electric field vector follows the same shape and orientation as the projection of the electron s path onto a plane perpendicular to the observation direction. 

The inertial confinement concepts utilize the idea of heating a pellet of D-T-fuel either by absorption of light from a powerful laser, a relativistic electron beam or a heavy ion beam to the ignition temperature in a time short compared to vaporization of the pellet. The reaction time must also be short compared with the confinement time to allow a sufficient burn up of the fuel for energy gain. In addition, the range of the 3.5 MeV a-particles has to be shorter than the pellet radius if their energy is to be efficiently deposited in the pellet. 

Several large experiments are planned which should demonstrate pellet gain in excess of unity, i.e. scientific feasibility. The experiments with laser drivers are under development e.g. at Lawrence Livermore Laboratory and at Los Alamos Scientific Laboratory (USA)20 those with relativistic electron beams at Sandia Laboratory, Albuquerque (USA)21 and at Kurchatov Institute (USSR). They are scheduled to start operation in the early 1980 s. 

The advent of relativistic electron beams generated from laser-plasma interactions opens the possibility of producing X-rays in the keV to 100 keV... 

The energy, Eth, of the X-rays produced depends on the interaction angle between the laser and the relativistic electron beam, electron beam direction, 9. It is given by [18] as... 

In comparison with X-rays, an electron beam can have a very short wavelength, which can be calculated according to the equation below when the relativistic correction is considered ... 

In this relation, Z is the atomic nmnber of neutral particles, providing the beam stopping o is their number density and v is the stopping electron velocity. In the case of relativistic electron beams with the electron energies of 0.5-1 Me ( the energy losses can be numerically calculated by the following relation ... 

Numerically, this ionization rate coefficient is about 10 -10 cm /s. The total rate of ionization by relativistic electron beams can be expressed in this case as a function of the electron beam concentration Ub or the electron beam current density p (c is the speed of light) ... 

Plasma Radiolysis of CO2 Provided by High-Current Relativistic Electron Beams... 

Dissociation of CO2 can be effectively stimulated by relativistic electron beams (Legasov et al., 1978 Vakar et al., 1978). The dominating mechanism of CO2 dissociation is usually related in this case to electronic excitation of the molecules. The major difference between plasma radiolysis and conventional radiolysis is related to the contribution of collective non-linear effects, or in other words synergetic effects, in the dissociation process. While conventional radiolysis is based on CO2 dissociation provided by individual high-energy... 

Analysis of kinetic equation (5-131) shows the effective Maxwellization of plasma electrons, generated by a high-crrrrent relativistic electron beam, and as a result /x 1 becomes possible when ionization degrees are sufficiently high ... 

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