German-Armenian Student Course on Accelerator Physics

Vibrating wire monitors and beam profile measurements


In this practical course you will learn how to measure the beam profile in accelerators. You will be familiarized with a new diagnostic instrument for beam profile measurement – the Vibrating Wire Monitor (VWM), the operation principle of which is based on a simple and clear idea of a mechanical resonator (stretched wire) and its frequency dependence on the wire tension. The wire tension, in turn, depends on its temperature, i.e. the instrument is essentially a precise thermometer. The Lab work will be done on three setups: VWM as a precise thermometer, VWM scan test on a laser beam and demonstration of a profile measurement by VWM at the AREAL accelerator electron beam. All the practical tasks are preceded by theoretical familiarization with the corresponding topics.

Here are the aims of all tree setups.

Aim of Setup 1: VWM as a precise thermometer
Introducing the topic – VWM as a precise thermometer.
Experiment of wire heating by a DC current through the wire.
Excitation of wire oscillations by a special electronic unit, data acquisition, processing and analysis.
Aim of Setup 2: VWM scan test on laser beam
Profile measurement experiment on a laser beam at different scan speeds.
Aim of Setup 3: Demonstration of an electron beam profile measurement at AREAL

The AREAL accelerator diagnostics is introduced, including the VWM installation in the beam line. Recovering the beam profile from frequency data.

The result of this beam profile measurement will be compared with the beam profile measurement by a different device, e.g. a YAG screen. Differences of the results will be discussed.

In the end of the course you will learn:

The theoretical part of wire oscillation physics; to work with software, as a result of which you will become familiar with traditional and new methods for measuring transverse beam profiles in accelerators.


General view of the double wire – VWM                              Vibrating wire front-end

as a precise thermometer