Patent ID: 8421029
Filing Date: 2013-04-16
Classification: H01J

Abstract:
1. A field-isolating device for a Wien filter, comprising: two field-terminating plates being perpendicular to an optical axis of the Wien filter and sandwiching the Wien filter with two axial gaps, wherein each of the two field-terminating plates is made of a material of both electric and magnetic conductor and has an opening aligned with the optical axis of the Wien filter and for particles passing through; and a field-terminating tube being parallel to the optical axis of the Wien filter and enclosing the Wien filter with a radial gap, wherein said tube is made of a material of magnetic conductor, wherein said two field-terminating plates and field-terminating tube are configured to make an electric dipole field and a magnetic dipole field leaking out of the Wien filter vanish away rapidly outside the field-isolating device.