Concept of beamline and sample chamber - 11th of June 2009

We have designed part of the beam line that will be placed behind the picosecond electron accelerator. It will consist of a view elements that have the function to illuminate the cathode surface with UV pulses, guide the electron beam to the sample and place different samples in the electron beam. All will take place in vacuum.

The samples will be placed on a big wheel so that we can test more that one sample before we have to open the sample chamer. The sample wheel can be moved with respect to the electron beam, so that the total area of the sample can be used to study the properies. The sample chamber has to laser beam lines that cross the samples at exactly the same position as the electron beam. We have the possibility to use to different wavelength regions to probe the sample, that are the VISible and the InfraRed.

Below, you will find to pictures showing the global layout. One is showing only the essential parts of the beam line and sample chamber. The other is showing the total cross section.

So, far a few components have been realized. One of them is the big sample chamber and the sample wheel. Those components are ready to be installed as soon as the RF processing is succeshully finished.

Essential components of the beam line and sample chamber: UV incoupling, steering magnets, filter wheel, beam monitor and faraday cup.

Total cross section of the accelerator, beam line and sample chamber.

Poster presented at PAC 2009 - 11th of June 2009

Here is a copy of the poster presented at the Particle Conference 2009 (PAC 2009) in May 2009 in Vancouver Canada.


All rights reserved, Copyright (c) 2009, Delft, The Netherlands

Contribution to PAC 2009 - 11th June 2009

We presented our accelerator setup as part of a shared contribution to the Particle Accelerator Conference 2009 (PAC 2009) held in May in Vancover Canada together with Eindhoven University of Technology and Pulsar Physics from The Netherlands.

Procedings will be published later. Below you can find the abstract. For more information

Design, construction and operation of the Dutch rf-photoguns

S.B. van der Geer, M.J. de Loos, W. op ‘t Root, W. Knulst, W. van Dijk, G.J.H. Brussaard, O.J. Luiten

Three different S-band rf-photoguns have been constructed by Eindhoven University of Technology in the Netherlands: A 1.5-cell, a 100 Hz 1.6-cell, and a 2.6-cell. They share a design concept that differs from the ‘standard’ BNL-gun in many aspects: Individual cells are clamped and not brazed saving valuable manufacturing time and allowing damaged parts to be replaced individually. The inner geometry employs axial incoupling, inspired by DESY, to eliminate any non-cylindrically symmetric modes. Elliptical irises, identical to a 2.6-cell design of Strathclyde University, reduce the maximum field on the irises and thereby reduce electrical breakdown problems. The manufacturing process uses single-point diamond turning based on a micrometer-precise design. The overall precision is such that the clamped cavities are spot-on resonance and have near-perfect field balance without the need for any post-production tuning. Operational performance of the three Dutch rf-photoguns will be presented.

Update on status - 11th of June 2009

The current status of the system is that we are preparing for the first RF processing procedure to train the copper cavity. A few systems have to be put into operational before we can start, such as cavity temperature control, vacuum control and RF power control.

Last year we have had many setback, such as vacuum leaks to do cracks in the soldering. All have been repared and since the end of the summer 2008 the cavity has been installed into its stainless steel container. After that, a vacuum backout session has been conducted to clean the cavity.

In September 2009 we also finished a demonstration version of the RF cavity made out of brass that has been caoted by gold. I have added a few pictures.

Side view of the RF cavity. On the left is the cathode surface and on the right the coaxial incoupling of RF power that is also the electron beam exit.

On this side you can clearly see the springs that clamp the cavity cells together and press it on the RF in coupler. You can also see the cooling channels and the thermocouples to measure the internal temperature.

On this side you can see the coaxial structure. The RF in coupler or mode transformer is connected to the cavity on this side.