Micropole undulator

A method for causing transverse undulations in the trajectory of a charged particle travelling along a substantially linear trajectory, the method comprising:

• providing a pair of parallel jaws between which extends an undulator axis positioned to coincide substantially with the trajectory of moving charged particles, each jaw comprising a plurality of permanently magnetized bars, the bars being separated by spaces, each bar being aligned transversely to the axis so that each bar produces a primary magnetic field substantially parallel to all others;
• and
• providing a biasing magnetic field extending across the axis in a direction substantially opposite to the primary fields produced by the bars such that the strengths of the primary fields are reduced and the net effect is to provide a plurality of secondary fields extending between opposed spaces of the two jaws in a direction substantially opposite that of the primary fields.

An undulator for causing transverse undulations in the trajectory of a charged particle travelling along a substantially linear trajectory, the undulator comprising:

• first and second opposed jaws located on opposite sides of an undulator axis which is positionable substantially to coincide with the trajectory of moving charged particles, each jaw comprising a substantially planar layer of magnetizable material, alternating regions of which layer have been magnetized to provide oppositely directed magnetic fields, all such fields extending substantially perpendicular to the layer,
• the two jaws being positioned such that the respective layers face each other and extend parallel to the undulator axis.

In an undulator for causing transverse undulations in the trajectory of a charged particle travelling along a substantially linear trajectory, at least one jaw comprising a continuous layer of a magnetizable material, the layer having two substantially continuous, parallel and planar faces, discrete regions of which layer have been permanently magnetized to provide magnetic fields that are oriented transversely to the faces.

An undulator for causing transverse undulations in the trajectory of a charged particle travelling along a substantially linear trajectory, at least one jaw comprising:

• continuous layer of magnetizable material, the layer having two substantially continuous, parallel and planar faces and a plurality of side edges and being sufficiently thick to retain sufficient coercive force to cause particle deflection, alternating regions of the layer being permanently magnetized to provide oppositely directed magnetic fields that are oriented transversely to the faces and having aspect ratios of no more than about 1.0;
• and
• a substrate over which the layer is superposed for dimensional stability, the substrate having a smooth surface which conforms to the faces and being made of a magnetizable material that has a low magnetic remanence.

A method for providing an undulator to cause transverse undulations in the trajectory of a charged particle travelling along a substantially linear trajectory, the method comprising:

• providing a body having at least one substantially planar layer of magnetizable material;
• magnetizing regions of the layer by subjecting the layer, at periodic intervals along a line, to transverse magnetic fields, so that adjacent regions of the layer acquire a magnetization substantially aligned with each other, but a magnetization whose strength and sign can differ from region to region.,
• positioning two of the bodies such that the respective layers extend substantially parallel to an undulator axis therebetween, which axis is positionable substantially to coincide with the trajectory of moving charged particles.