Patent Number: 043226221
Section: summary

BACKGROUND OF THE INVENTION The present invention relates to an achromatic magnetic deflection device for deflecting by an angle .phi. a beam of charged accelerated particles (electrons for example), these particles being able to present a large range of moments of quantities of movement. The deflection device of the invention enables in particular a beam of electrons accelerated between 10 and 20 Mev for example to be deflected by an angle .phi.&gt;.pi., without having to modify the values of the magnetic fields created in the air gaps of the pole pieces forming part of the deflection device. SUMMARY OF THE INVENTION It is an object of the invention to provide a device for the achromatic magnetic deflection of a beam of accelerated charged particles comprising at least one electromagnet having pole pieces delimiting air gaps in which are created magnetic fields having the same direction and specific values so that the paths of the particles have the form of loops whose lengths depend on the momentum of the particles, these pole pieces delimiting a first, a second and a third magnetic sector disposed one after the other and joined together, the whole of these magnetic sectors having a plane of symmetry perpendicular to the plane of the mean path of the beam of particles and intersecting this plane along an axis XX, the magnetic deflection device presenting successively to the beam of particles a flat input face, a first curved face, a second curved face and a flat output face, the input and output flat faces forming therebetween an angle 2.alpha., the first and second curved faces, as well as the axis of symmetry XX, being substantially orthogonal to the different paths of the particles, the values of the magnetic inductions created in the first and third magnetic sectors being respectively equal to KB.sub.o, B.sub.o being the value of the magnetic induction in the second magnetic sector and K a numeric coefficient less than 1. The above and other objects, features and advantages of the present invention will become apparent from the following description, given solely by way of non-limiting illustration, when taken in conjunction with the accompanying drawings.