Magnetic deflecting and focusing device for a charged particle beam

Claim 1

A magnetic deflecting and focusing device for a beam of accelerated charged particles having an incident mean path T o , comprising, in combination, magnetic means for translating said beam in a direction perpendicular to said incident mean path T o to obtain a translated beam parallel to said incident mean path T o , the particle paths of said translated beam being dependent upon the momentum of said particles, and magnetic means for deflecting and focusing said translated beam upon a target having a predetermined position, said magnetic means for translating and said magnetic means for deflecting and focusing said beam being positioned and configured so as to achieve convergence of said particle beam on said target in two mutually perpendicular planes whose intersection is coincidental with the mean path of said beam emerging from said device, the positioning and configuration of said magnetic means further being such that momentum convergence of said particle beam is simultaneously achieved on said target substantially located on the axis corresponding to the mean path T o of the incident beam; said magnetic means for translating said beam comprising a first and a second electromagnet having respectively an entry face and an exit face parallel to one another; the entry face A 1 of said first electromagnet being perpendicular to said incident mean path T o and the exit face B 2 of said second electromagnet being perpendicular to said particle beam emerging from said second electromagnet; the entry face A 2 of said second electromagnet being parallel to the exit face B 1 of said first electromagnet and said faces A 2 and B 1 being spaced of an interval of: d = 2r/tg Θ the normal to said beam at the exit face B 1 and at the entry face A 2 being respectively at an angle Θ with said entry face A 1 and said exit face B 2 and r being the radius of curvature of said particle beam within said first and second electromagnet.