Process of and apparatus for cold-cathode electron-beam generation for sterilization of surfaces and similar applications
AssigneeTetra Pak Developpement SA
InventorRichard N. Cheever
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Abstract
This disclosure is concerned with a process of and apparatus for producing relatively low energy electron beams through pulsed cold-cathode beam generation in a mode of operation involving an important intermediate region of a substantially linear depth-dose profile characteristic that reduces the sensitivity to possible voltage variations, and with improved triggering structures that significantly improve reliability and minimize erratic pulse generation and missing pulses, thus particularly adapting the process and apparatus for such stringent applications as production-line sterilization of surfaces, materials or workpieces passed by the apparatus.
Claims24
A process of insuring the reliability of the production of repetitive impulses of electron-beam energy for production-line irradiation purposes, that comprises, repetitively generating electric-discharge pulses;
- applying the pulses repetitively to draw electron beam impulses from a cold cathode to and through an electron-pervious window anode;
- disposing the window anode adjacent a portion of a region along which products-to-be-electron-beam irradiated are passed;
- causing the impedance presented by the cold cathode-window anode to the impedance presented by the pulse generating step to produce a substantially linear electron-beam dose versus penetration depth characteristic curve of relatively low slope compared to the DC characteristic curve in the region near the one-half dose region of said characteristic curves, thereby to reduce the sensitivity of the electron beam impulses to possible voltage variations during the pulse generating step in order to insure substantially uniform irradiation of the products passing along said region.
Apparatus for electron-beam-irradiating surfaces passed along a predetermined region, having, in combination, electric-discharge repetitive pulse-generating means;
- electron gun means comprising cold cathode means and electron-pervious window anode means connected to the pulse-generating means repetitively to draw electron beam impulses from the cold cathode means to and through the window anode means;
- and means for disposing the window anode means adjacent a portion of said region along which products-to-be-electron-beam irradiated are passed;
- the relative impedances of the pulse-generating means and the electron gun means being predetermined to produce a substantially linear electron-beam dose versus penetration depth characteristic curve of relatively low slope compared to the DC characteristic curve in the region near the one-half dose region of said curves.
Dependencies are inferred from the claim text.