Atomic Energy of Canada Limited

Stanley O Schriber

Joseph McKeown

Edward A Heighway

John S Fraser

Samuel B Hodge

Kenneth J Hohban

L Warren Funk

An S-band standing wave electron accelerator structure having a multiplicity of resonant accelerating cavities and resonant coupling cavities mounted sequentially in an alternating accelerating cavity-coupling cavity pattern along an accelerator axis, with adjacent cavities separated by a common wall. The common walls and end walls of the structure have beam holes concentric with the axis, and the common walls further have two slots for coupling energy between the cavities. To prevent direct coupling between the accelerating cavities which are separated by a coupling cavity, the coupling slots in one wall of the coupling cavity are rotated approximately 90.degree. about the accelerator axis with respect to the coupling slos in the other wall. The structure is assembled by brazing a number of conductive segments together. Each segment forms half of each of the adjacent cavities having the common wall and thus consists of half of an accelerating cavity and half of a coupling cavity. The outer profile of the segments may be circular, square, or hexagon. The cooling system is simplified if a combination of circular and square segments, or only hexagonal segments are used.

S-Band standing wave accelerator structure with on-axis couplers

A charged particle beam deflector having a bimodal resonant cavity through which a charged particle beam is passed along the cavity axis. The cavity is excited in a first mode by applying a first rf signal to the cavity through a first magnetic feed loop on the side of the cavity, and in a second mode orthogonal to the first mode by applying a second rf signal to the cavity through a second magnetic feed loop located on the side of the cavity at a circumferential angle of approximately 90.degree. from the first feed loop. The first mode deflects the beam along a first diametric axis passing through the cavity axis and the first loop location and the second mode deflects the beam along a second diametric axis which is substantially perpendicular to the first diametric axis. The rf signals to the feed loops are normally of identical frequency but may differ in ampitude and in phase from one another or from the beam to provide various controlled scan patterns.

Charged particle beam deflector

The electron beam monitor includes two long, thin foil elements which are sequentially moved through an electron beam to be measured, in directions transverse to the beam and perpendicular to one another. The electron beam striking the elements produces forward directed bremsstrahlung radiation that is detected by a series of detectors which are positioned circumferentially about the beam path. A measuring circuit measures the radiation intensity as a function of the foil position to provide beam current, profile and position information. To simultaneously monitor a second beam travelling in a direction opposite to the first beam, a second series of detectors are positioned circumferentially about the beam path to detect forward directed radiation produced by the second electron beam as it strikes the foils.

Electron beam current, profile and position monitor

The klystron-resonant cavity accelerator system includes an accelerator structure having one or more sections of intercoupled resonant cavities which, with the output resonant cavity of a klystron, forms an integral rf coupled resonant cavity system for energizing the accelerator. The klystron and resonant cavity accelerator thus coupled also constitute a single evacuated system. The klystron output resonant cavity may be coupled to a resonant cavity in each of the accelerator sections by means of an energy coupling iris or by means of a intervening resonant coupling cell.

Klystron-resonant cavity accelerator system

A double pass linear accelerator which is used in a radiation therapy unit to provide electron radiation or photon bremsstrahlung radiation when combined with an appropriate target. The accelerator operates in a standing wave mode and includes an accelerating section, a charged particle source and injection section, a microwave source operating in the S band and adapted to excite the accelerating section and a reflector system which is mounted at one end of the accelerating section to reflect a particle beam which has been accelerated due to one pass, back into the accelerating section such that it may be further accelerated. The distance between the reflector is made adjustable to provide for output particle energy variation.

Double pass linear accelerator operating in a standing wave mode

An X-ray beam flattener of predetermined symmetrical shape for attenuating the radiation intensity of the beam in decreasing amounts as the angle from the central axis increases. The symmetrical shape is made from a low Z, high density material such as Al.sub.2 O.sub.3 BeO, BeAl.sub.2 O.sub.4, B.sub.4 C or SiC. A further thin layer of high Z material may be coated on the forward end of the symmetrical shape to absorb low energy photons.

X-ray beam flattener

In the 2.pi./3 standing wave mode of energizing resonant cavities, a regular field pattern is set up between adjacent cavities which follows the sequence + (or -), - (or +) and zero. In the novel system of this invention, two series of cavities are used to form accelerating sections wherein the standing wave is propagated successively from one section to the other such that adjacent cavities in each of the sections have positive and negative fields and the resonant coupling cells between the sections have zero fields. This system is used in the acceleration of two beams by a single driving source or in a double track race-track microtron.

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Deep River, Canada

Stanley O Schriber