Electron beam control for barely separated beams

Abstract

A method for achieving independent control of multiple beams in close proximity to one another, such as in a multi-pass accelerator where coaxial beams are at different energies, but moving on a common axis, and need to be split into spatially separated beams for efficient recirculation transport. The method for independent control includes placing a magnet arrangement in the path of the barely separated beams with the magnet arrangement including at least two multipole magnets spaced closely together and having a multipole distribution including at least one odd multipole and one even multipole. The magnetic fields are then tuned to cancel out for a first of the barely separated beams to allow independent control of the second beam with common magnets. The magnetic fields may be tuned to cancel out either the dipole component or tuned to cancel out the quadrupole component in order to independently control the separate beams.

Claims

1. A method of independently controlling multiple, barely separated beams in a common transport pipe, comprising: providing a magnet arrangement including at least two multipole magnets spaced closely together and having a multipole distribution including at least one odd multipole and one even multipole; placing the closely spaced multipole magnets in the path of the barely separated beams; and tuning the magnetic fields to cancel out a first of the barely separated beams to enable independent control of the second beam with common magnets.

2. The method of claim 1 further comprising tuning the magnetic fields to cancel out the dipole component.

3. The method of claim 1 further comprising tuning the magnetic fields to cancel out the quadrupole component.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a graph depicting a method for achieving independent control of slightly space-separated beams with a quadrupole and a sextupole magnet.

DETAILED DESCRIPTION

(2) The invention is a method to independently control multiple, barely separated beams in a spreader/recombiner by directing the beams through at least two multipole magnets spaced closely together or through a magnet with two or more multipoles. The multipole distribution needs to contain at least one odd and one even multipole, so that the magnetic fields can be tuned to cancel out for one of the beams. This allows independent control of the other beam(s) with common magnets.

(3) The canceling of the magnetic fields can be done by two methods, including 1) canceling out the dipole component, which will in general leave some defocusing effect, but doesn't steer the beam in another direction, and 2) canceling out the quadrupole component, which method will generally result in a remaining dipole field, but there is no defocusing.

(4) With reference to FIG. 1, there is shown a method for independently controlling multiple, barely separated beams in a spreader/recombiner by having them go through at least two multipole magnets spaced closely together or through a magnet with two or more multipoles. The multipole distribution needs to contain at least one odd and one even multipole, so that the magnetic fields can be tuned to cancel out for one of the beams. This allows independent control of the other beam(s) with common magnets. Slightly space-separated beams can be focused with a quadrupole and a sextupole magnet. Beam 1 sees no focusing field whereas beam 2 sees the focusing field.

(5) According to the present invention there is proposed a method of independently controlling multiple, barely separated beams in a common transport pipe or spreader/recombiner, including the steps of: 1) providing a magnet arrangement including at least two multipole magnets spaced closely together and having a multipole distribution including at least one odd multipole and one even multipole; 2) placing at least two closely spaced multipole magnets in the path of the barely separated beams; and 3) tuning the magnetic fields to cancel out for a first of the barely separated beams to allow independent control of the second beam with common magnets.

(6) Tuning the magnetic fields may include: 1) tuning the magnetic fields to cancel out the dipole component, or 2) tuning the magnetic fields to cancel out the quadrupole component.

(7) Although the description above contains many specific descriptions, materials, and dimensions, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.