Bunch shape is one of the most important and interesting characteristics of a beam in ion linear accelerators. Recently detectors of bunch shape with a transverse scanning of low energy secondary electrons found application in several accelerators. The principle of operation of the detectors is based on a coherent transformation of a longitudinal structure of a beam under study into a transverse distribution of a secondary electron beam through RF scanning. There are three modifications of the detectors: bunch shape monitor, bunch length (shape) and velocity detector and three dimensional bunch shape monitor. The principle of operation of the detectors as well as the peculiarities of the structure and the design of the detectors are described. To demonstrate the possibilities of the detectors the results of measurements with different detectors made at different accelerators are presented.

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Methods and instrumentation for bunch shape measurements

This introductory course aims at a reasonably complete coverage of beam diagnostic devices used in linear and circular accelerators and in primary beam lines. The weight is on the concepts and the indication of variants, while for technical details the reader is referred to the literature. The present updated version replaces those from previous General Accelerator Physics Courses.

/pdf/beam-diagnostics-for-accelerators-mm89xf1thr.pdf

Beam diagnostics for accelerators

The properties of charged particle beams associated with the distribution of the particles in energy and in time can be grouped together under the category of longitudinal emittance. This article is intended to provide an intuitive introduction to the concepts of longitudinal emittance; to provide an incomplete survey of methods used to measure this emittance and related properties of bunch length and momentum spread; and to describe the detailed design of a 6 Ghz bandwidth resistive wall current monitor useful for measuring bunch shapes of moderate to high intensity beams. Overall, the article is intended to be broad in scope, in most cases deferring details to cited original papers.

/pdf/longitudinal-emittance-an-introduction-to-the-concept-and-2w1uvyjk5g.pdf

Longitudinal emittance: An introduction to the concept and survey of measurement techniques including design of a wall current monitor

Laser photodetachment can be used on high current, high energy H{sup {minus}} beams to carry out a wide variety of beam diagnostic measurements parasitically during normal operation, without having to operate the facility at either reduced current or duty cycle. Suitable Q-switched laser systems are small, inexpensive, and can be mounted on or near the beamline. Most of the proposed laser-based diagnostics techniques have already been demonstrated.

https://epaper.kek.jp/l98/PAPERS/TU4062.PDF

Laser diagnostic for high current H− beams

To measure a longitudinal charge distribution in an ion linac beam it is preferable to apply bunch shape monitors using a low energy secondary emission electrons. Monitors of this type and their development are discussed. Different varieties of rf deflectors for a transverse modulation of secondary electrons are considered. Preliminary parameters of a bunch shape monitor for the SSC linac are presented. A detector to measure both longitudinal and transverse distributions of a two component ion beam is described.

Richard L. Witkover

Papers

A non-destructive bunch length monitor for a proton linear accelerator