Low-Energy Electron Accelerators

Common designs of industrial low-energy accelerators. (Mehnert, R., Pincus, A., Janorsky, 1., Stowe, R., and Berejka, A., UV EB Curing Technology Equipment, SITA Technology Ltd., p. 138 (1998). With permission from SITA Technology Ltd.) 

The electron gun consists of a spiral-shaped tungsten cathode and a Wehnelt cylinder. These two components not only constitute the electrodes of the acceleration gap, but also form the optical assembly to control and shape the electron beam. Current signals are linear and have a repetition frequency 

Single-stage scanned beam accelerator with a range of accelerating voltages from 80 to 300 kV. (Courtesy of Elektron Crosslinking AB.) 

The process control is provided by programmable process controllers (PLCs), which are flexible and upgradable. The addition of man-machine interfaces (MMls) based on personal computers and common software systems allows not only system control and interlocks, but also a history 

Self-shielding EB processor with the accelerating voltages of 800 kV. (Courtesy of Nissin Electric.) 

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Schematic of a microwave linear accelerator or linac The three most common designs of industrial low-energy electron accelerators...

Mondelaers, W. 1998. Low-energy electron accelerators in industry and applied research. Nucl. Instr. Meth Phvs. Res. B 139 43-50. 

VFD tubes operate by the same principle as CRTs but use low-energy electrons (10-100 V) to excite the phosphor. The electrons are emitted from a cathode (wire) and are accelerated and controlled so that they bombard a phosphor-coated anode, causing the phosphor to emit light. ZnO Zn (green-emitting) phosphors were used in early VFD devices, but as the application range expanded, demand developed for multicolored displays.29... 

In plasmas, the gas is ionized giving ions and electrons. Both the ions and the electrons are accelerated by the electric field either ac, RF, or dc arc of the plasma. The average kinetic enei of the gas, a measure of its temperature, has three contributions one from the gas molecules, one from the ions, and one from the electrons. Due to their low mass, electrons accelerate to very high velocities in the electric field and can dominate the average kinetic energy of the system. For this reason, temperatures of 15,000°C are possible with plasma reactors. As a restdt of the ionization of gases, the reactions that can take place are different than those in a nonionized gas. The reaction kinetics are also enhanced in an ionized gas because the transition states of reactions are not difficult to achieve with ions as reactants. 

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