Electron beam power

The basic electrical parameters of an electron beam processor are its acceleration voltage, the electron beam current, and the electron beam power. The ratio of electron beam power and the input electrical power defines the efficiency of an electron accelerator. The acceleration voltage determines the energy of the electrons, as pointed out in Section 2.2. 

Process parameters involve line speed if dose rate and line speed are combined, the dose delivered to the product to be cured can be calculated. A processor-specific yield factor depends on the relationship between the beam current and line speed. The dose-speed capacity of a processor is given by the product of the line speed and the delivered dose at maximum electron beam power.27... 

Electron beam power Product of the acceleration voltage and of the electron beam current, expressed in kW (1 kW =10 mA x 100 kV). 

Under these conditions, a single curing station at an electron beam power output of approximately 300 watts per inch is adequate to cure such a coating at a line speed of 300 feet/ minute. For the application treated here, a 175 kV x 155 cm unit operating at a beam current of 100 MA would suffice -this is the CB 175/155/100 unit - it provides a beam output of 17.5 kW at an input power of 21.5 kilowatts. 

Electron beam assisted deposition involves the application of a stream of electrons to evaporate the source material of the deposited film. The electron beam power can be established at a very high value. This tends to enhance the deposition rate. However, the high-energy beam may cause damage on the surface of the substrate. 

The data shown in Fig. 10 indicate that the treatment times per pallet with a density of 0.8 g/cu cm would be about 8.5 minutes at 5.0 MeV and 4.8 minutes at 7.5 MeV. The treatment time increases with the product density, because this calculation is based on the minimum dose in the middle of the pallet. With doses higher than 2.0 kGy, which would be required for most polymer modifications, the time would increase in direct proportion to the dose. For example, assuming 300 kW of electron beam power at 7.5 MeV, the treatment time for a 20 kGy dose would be about 48 minutes per pallet with a density of 0.8 g/cu cm. At the other end of the density scale, the treatment time for 20 kGy with densities in the range of 0.1 to 0.3 g/cu cm would be about 22 minutes per pallet. 

From eqns. (77) and (78), the vapour cloud parameters n and A can be also obtained by variation of the coefficients. Fig. 49 shows the measured vapour distribution curves of aluminium obtained by evaporations with a standard commercially available 270° bent electron beam gun. A 12kW, lOkV electron beam power supply and a quartz crystal thickness and rate monitor were used [256]. At an aluminium evaporation rate of 1.8 nm s 1, the cosine exponent equals n = 2.3 with no isotropic component A = 0. With increasing rate the exponent increases and also the isotropic component appears. With rates of 10.5 and 81.4 nm s"1 the corresponding characteristic data are n = 4, A = 0.14 and n = 5.8, A = 0. 14. 

Figure 5-51. CO2 dissociation in plasma-beam discharge. Partial pressures of the dissociation products as function of electron beam power (1) CO2 (2) CO (3)02.

Figure 6-18. Dependence of NO yield in non-equilibrium stationary plasma-beam discharge on electron beam power at gas flow rate 120 L/s and different levels of gas pressure (1) p = 5- 10 2 Torr (2) p = 0.2Torr.

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