Sterilization by low energy electron beam

Abstract

A sterilization apparatus wherein one or more electron beam tubes are used to direct electron beams into an ambient gaseous environment to create an electron plasma cloud into which non-sterile target objects may be moved. The electron plasma cloud is formed by interaction of the electron beam with the ambient atmosphere. Helium or other like gaseous may be used to expand the effective volume of the electron plasma cloud. Manipulators are used to move target objects in the electron plasma cloud, exposing non-sterile surfaces to the cloud and then joining the surfaces together where appropriate. The beam tube used to generate the electron beam has a thin low energy absorbing window which allows relatively low energy beams to be used, minimizing damage to materials within the surface of the target objects.

Description

TECHNICAL FIELD[0001]The invention relates to beam sterilization of surfaces of objects and, more particularly, to sterilization which relies mainly on electron beam interaction with surfaces of objects.BACKGROUND ART[0002]In the fields of medicine, pharmaceutical production, and food processing there is a critical need for sterilization to protect against the danger of harmful microorganisms. Most of the sterilization methods currently in use require the sterilizing agent to systemically permeate the article being sterilized. These methods include heat sterilization, where the object to be sterilized is subjected to heat and pressure, such as in an autoclave. The heat and pressure penetrates though the object being sterilized and after a sufficient time will kill the harmful microorganisms. Gases such as hydrogen peroxide or ethylene oxide have also been used to sterilize objects. For the complete sterilization of an object, the gas must permeate the entire object. An alternate ste...

AI Technical Summary

Benefits of technology

[0009]The above object has been achieved with a sterilization chamber featuring one or more electron beam tubes generating low energy electron beams, preferably under 100 <?delete-start id="DEL-S-00001" date="20070529" ?>kV<?delete-end id="DEL-S-00001" ?> <?insert-start id="INS-S-00001" date="20070529" ?>keV<?insert-end id="INS-S-00001" ?>, in air or a surrounding gas at atmospheric pressure close to target objects to be sterilized. The low energy beams interact with air or surrounding gas to cause some ionization but a substantial fraction of the beam energy is delivered to the surface of a target object causing the object to be sterilized. A multiplicity of beam tubes may be used to eliminate shadows in cases where the target object has complex surface contours. Each tube has a stripe shaped beam which forms a plasma cloud in the beam path a short distance from a window in the beam tube by interaction of the electron beam with the ambient environment. Unlike metal foil windows of the prior art which cause high beam energy losses, the window of the beam tube used herein is preferably a thin semiconductor window which reduces losses in a high energy electron beam.

[0011]A plurality of electron beam tubes can be arranged in a spatial pattern to create a composite plasma cloud which will eliminate any hidden surfaces or “shadows” of three dimensional objects that have complex surfaces. Also, a plurality of electron beam tubes can be arranged in patterns which would cover a large two dimensional area. For example, a triangular pattern of electron beam tubes would cover a large circular or triangular pattern on a flat surface, compared to the coverage of a single beam tube.

Problems solved by technology

Without introduction of helium an electron beam “plasma cloud” can still exist, but its effective range is limited to a space quite close to the window of the electron beam tube.

Images