Patent
1989-10-31
1992-04-21
O'Shea, Sandra L.
H01S 2312
Patent
active
051072211
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an electron accelerator. It is used in the irradiation of various substances, such as agro-alimentary products, either directly by electrons, or by X-rays obtained by conversion on a heavy metal target.
An electron accelerator is known, which in general terms comprises a resonant cavity energized by a high frequency field source and an electron source able to inject electrons into the cavity. If certain phase and velocity conditions are satisfied, the electrons are accelerated by the electric field throughout their passage through the cavity.
In accordance with this principle, in certain accelerator types, the electron beam passes through the cavity several times. The apparatus then comprises an electron deflector receiving the once accelerated beam, which then deflect it by approximately 180.degree. and reinject it into the cavity for a further acceleration. A second deflector can again deflect the beam which has undergone two accelerations, so that it is made to pass through the cavity a third time and in this way obtain a third acceleration and so on. Such an apparatus is e.g. described in French Patent 1 555 723 entitled "100 MeV continuously operating electron accelerator".
This type of accelerator suffers from the following disadvantage. During the first injection into the cavity, the electron beam follows a path coinciding with the axis thereof. Along this path the electric field only has a single component directed along the axis. Thus, acceleration of the electrons takes place and there is no deflection of the beam because there is no transverse component of the magnetic field.
However, during the second passage through the cavity, the electron beam takes a path which is no longer directed along said axis. A magnetic component perpendicular to the axial component of the electric field can act on the electron beam, so that the electrons are deflected. This deflection will depend on the phase of the electromagnetic field which leads to a dispersion of the beam and consequently part will be lost on the walls of the cavity. Moreover, this parasitic phenomenon increases during multiple passages,
However, multiple passage accelerators are known, which obviate this problem as a result of a special deflector structure. According to this variant, e.g. described in U.S. Pat. No. 3 349 335, the electrons perform a complete loop outside the cavity and are reinjected into its axis.
According to another variant described in FR-A-1 136 936, acceleration takes place in a resonant cavity and after each passage the electrons are deflected outside the cavity so that they pass round the same and are reinjected into the acceleration axis.
According to yet another variant, sometimes called the Duotron, the electron beam is reflected on itself and thus performs an outward and return travel along the cavity axis.
In these improved variants, the electron beam, during these multiple passages, still follows the path for which the deflecting fields are zero (the electric field is parallel to the velocity vector of the electrons and is oppositely directed).
However, these apparatuses have a complex construction. In the first two, the various electron paths have a common branch coinciding with the cavity axis, but the other branches are outside the cavity which increases the complexity and overall dimensions of the apparatus. In the last, there is a limitation to a single and outward and return path of the beam and it is not easy to solve the problem of reflecting the electrons back on themselves.
The present invention aims at obviating these disadvantages. For this purpose, it proposes an electron accelerator benefiting from the effects of multiple passages, whilst retaining the condition referred to hereinbefore concerning the absence of deflecting fields along the paths taken by the electrons and which simplifies the problems associated with the deflection and reinjection of the electrons into the accelerating cavity.
More specifically, the present invention relates to an electron accelerato
N'Guyen Annick
Pottier Jacques
Commissariat a l''Energie Atomique
O'Shea Sandra L.
LandOfFree
Electron accelerator with coaxial cavity does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electron accelerator with coaxial cavity, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electron accelerator with coaxial cavity will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1589950