Particle accelerators

Robert Baths de Graaf
Robert Baths de Graaf during a demonstration of its generator in 1922

Accelerators of charged particles - equipment for production of beams of electrons, protons and ions at high energies. Particle acceleration occurs due to their interaction with electrostatic or electromagnetic fields. In medicine charged particle accelerators used for radiation therapy and radiobiological research. Depending on the way of accelerated charged particle accelerators are divided into electrostatic (for example, generator van de Graaff), linear resonance, induction (see Betatron) and cyclic (cyclotron).
In electrostatic generator van de Graaff high voltage is generated by the accumulation on the surface of a hollow, conducting sphere of electric charge, which is served at it from the electrical generator by moving an endless belt. The acceleration of charged particles in a vacuum tube.

Electrostatic generator (van de Graaff) - an accelerator of charged particles. Consists of a high voltage source (actually electrostatic generator) and accelerating tube. The first successful design of such a system was proposed in 1929 van de Graaf (R. J. Van de Graaff). The principle of action of electrostatic generator consists in the following.
Electric charge from the generator is applied to the dielectric moving tape.
With this tape charges are transferred by the system of brushes on the inner surface of a hollow metal isolated areas - conductor (Fig). Thus, the field can be moved sufficiently large charge, the maximum amount of which is determined by electrostatic discharge it into outer space. With the increase in the size of areas the voltage increases. Currently, to increase the voltage at the minimum installation sizes electrostatic generator placed in a tank of gas, having a high dielectric strength (nitrogen, CFCs, carbon dioxide), under the pressure of up to 20 atmospheres.
Electrostatic generator can be used to speed up as electrons (see)and heavy particles - protons (see). The maximum energy of accelerated particles up to 10 MeV. Electrostatic generators are widely used in physics, technology, and medicine. In medicine used electrostatic generators with electron beam (see Electron radiation) as a source of hard bremsstrahlung (see)arising from the ingress of high-energy electrons to the target of a heavy element. Cm. also charged particle Accelerators.

electrostatic generator van de Graaff
Electrostatic generator van de Graaff:
1 - high-voltage electrode (conductor);
2 - ion or electron source;
3 - multiple-accelerating tube;
4 - insulating column;
5 - defocusing of the electron beam;
6 - thin aluminum foil;
7 - conveyor;
8 and 10 - charging and removable tip;
9 - moving "infinite" tape.