Wien filter
AssigneeU.S. Philips Corporation
InventorsNicolaas Hazewindus, Jacob Maria VAN Nieuwland
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Abstract
A Wien filter for selecting particles having a given velocity from a beam of charged particles. Such a Wien filter comprises means to maintain an electric field and a magnetic field, which fields extend at right angles to each other and each at right angles to the axis of the particle beam. By providing a gradient in the magnetic field by means of two coils which are present on either side of the said beam and the axes of which are substantially parallel to the electric field and in which the magnetic field strengths produced in the coils are directed substantially opposite to each other, both a focus of the particle beam in a more favorable place is obtained and a stigmatic reproduction is effected so that velocity separation is considerably simplified.
Claims5
A Wien filter for selecting particles having a given velocity from a beam of charged particles and comprising means to maintain an electric field and a magnetic field, which fields extend substantially at right angles to each other and extend each substantially at right angles of the axis of the said beam, which magnetic field is produced between the poleshoes of an electromagnet which has means to provide an adjustable gradient in the said magnetic field, said gradient being substantially parallel to the electric field, characterized in that the means producing the said gradient comprise two coils which are present on either side of the said beam and the axis of which extend substantially parallel to the electric field, the magnetic field strengths generated in the coils being directed substantially opposite to each other.
Dependencies are inferred from the claim text.