Developments of the TEUFEL injector racetrack microtron

In this paper we report on developments of the 25 MeV racetrack microtron (RTM) that will be the electron source for the second phase of the TEUFEL project, to generate radiation of 10 µm in a 2.5 cm period hybrid undulator. The theoretical understanding of this unconventional, azimuthally varying field type of RTM has been extended. A comparison of analytically calculated orbit stability with that based on measured data will be presented; orbit calculations using measured field data show the designed performance. Construction and tuning of the 1300 MHz, 2.2 MV microwave cavity have been completed, and signal level measurements have been performed. The overall assembly of the microtron is nearing completion. At present a vacuum pressure better than 5 × 10-7 Torr is achieved

Proposal for a race-track microtron with high peak current

In order to obtain high gain in a free electron laser a high-quality electron beam with high peak current is required. It is well-known that a microtron is able to produce a high-quality beam having low emittance and small energy spread (1%). Because a circular microtron has a limited high-current capability a race-track design is adopted for providing flexibility, better beam quality and of course higher peak current in the microbunch. Space charge problems may be severe in a microtron. It can be shown that bunching on certain specific subharmonic frequencies will lead to a strong reduction of the space charge problems. The general layout of our microtron design will be presented. The characteristics are: energy 25 MeV, micropulse 10° of the rf frequency of 3 GHz. Our aim is to come beyond the present state of the art with the following characteristics: relative energy spread 0.001, emittance 3 mm mrad, current in the micropulse 100 A, macropulse length 50 μs and subharmonic bunching at 1:64

Status of the "TEU-FEL" project

The free-electron laser of the TEU-FEL project will be realized in two phases. In phase I the FEL will be driven by a 6 MeV photoelectric linac. In phase II the linac will be used as an injector for a 25 MeV race-track microtron. Information is presented on some technical details and the status of the different subsystems

The "TEU-FEL" project

The free-electron laser of the TEU-FEL project will be based on a 6 MeV photo-cathode linac as injector, a 25 MeV race-track microtron as main accelerator and a hybrid, 25 mm period undulator. The project will be carried out in two phases. In phase one only the 6 MeV linac will be used, The FEL will then produce tunable radiation around 200 µm. In phase two the linac will be used as an injector for the microtron. The FEL will then produce tunable radiation around 10 µm. Technical information will be presented on the different subsystems

The injector microtron for the TEUFEL infrared laser

Progress is reported on a 25 MeV injector racetrack microtron for a 10 ¿m radiation free electron laser (TEUFEL project). The accelerator exhibits transverse focusing in 180° inhomogeneous two-sector dipole magnets which are slightly rotated with respect to each other in the bending plane. This provides closed orbits, isochronism and a large transverse acceptance. Details on this unconventional microtron focusing system will be given. An analytical treatment, based on conformal mapping, of the field near pole boundaries and at the hill-valley boundaries in the microtron dipole is compared with Poisson calculated results and with field measurements. The design of a model accelerating cavity is presented together with field measurements based on the perturbation ball method

Design study for the accelerating cavity of the racetrack microtron Eindhoven

A 17-cell bi-periodic standing wave slot coupled structure will be used as accelerating structure for the RaceTrack Microtron Eindhoven. The numerical design of the struc ture has been performed with the computer codes SUPERFISH and MAFIA. Analytical calculations for a bi-periodic accelerating structure with full end cells including direct coupling are presented. Equations giving the detuning of the chain mode frequencies for known individual cell er rors and coupling coefficients are derived. After numerical inversion these equations will be used for the final tuning of the cavity

Design study for the accelerating cavity of the racetrack microtron Eindhoven

A 17-cell bi-periodic standing wave slot coupled structure will be used as accelerating structure for the RaceTrack Microtron Eindhoven. The numerical design of the struc ture has been performed with the computer codes SUPERFISH and MAFIA. Analytical calculations for a bi-periodic accelerating structure with full end cells including direct coupling are presented. Equations giving the detuning of the chain mode frequencies for known individual cell er rors and coupling coefficients are derived. After numerical inversion these equations will be used for the final tuning of the cavity

A microtron accelerator for a free electron laser

A racetrack microtron as a source for a free electron laser is being constructed. It will accelerate electrons up to 25 MeV to provide 10 µm radiation in a hybrid undulator with a periodicity distance of 25 mm. The aim is to accelerate 100 A bunches of 30 ps pulse length at 81.25 MHz. This frequency is chosen to minimize cavity loading, by avoiding simultaneous presence of more than one bunch in the microtron cavity. The self-focusing longitudinal action of the microtron assures a small energy and phase spread of the outcoming beam. Transverse focusing will be provided by applying edge focusing at valley boundaries in the sector magnets. An analytical theory and computer simulations have been set up and are being further developed for studying the effects of space charge during acceleration. Details of calculations and construction will be given