Åke Andersson

The MAX IV storage ring project

The design of the MAX IV 3 GeV ultralow-emittance storage ring is presented and the implementation of solutions to the technological challenges imposed by the compact multi-bend achromat lattice are described.

The MAX II synchrotron radiation storage ring

A 1.5 GeV third generation storage ring optimised for the VUV and soft X-ray spectral region is currently being built at MAX-lab. The magnet lattice, ring architecture and production choices are optimised to fit within rather tight boundary conditions without sacrificing performance. In this paper, the magnet lattice, light characteristics, injection and technical solutions for the ring are presented.

Coherent synchrotron radiation in the far infrared from a 1-mm electron bunch

The coherent generation of synchrotron radiation by an electron storage ring is predicted for wavelengths equal to or longer than the electron bunch length. With typical bunch lengths of approximately 1 cm, diffraction and chamber-screening effects have so far blocked observation of coherent radiation from a conventional radiation beamline. In the low-energy, second-generation light source MAX-I, the magnet lattice has been tuned to a small momentum compaction factor, allowing rms bunch lengths as short as 1 mm. Here we report the coherent far-infrared emission observed from such a bunch. The paper discusses the origin of coherent synchrotron radiation for Gaussian and non-Gaussian electron bunches, and the procedure used to generate such bunches. The emission was characterized using the infrared beamline at MAX-I, including an interferometer, a liquid-helium-cooled bolometer detector, waveguide high-pass filters, and a conductive-grid polarization filter. The intensity of the coherent radiation is greater by a factor of 2×103 to 6×103 than normal incoherent synchrotron radiation, and is seen between 8 and 22 cm-1.

Beam profile measurements at MAX

An electron beam profile monitor system is described. It utilizes the visible bending magnet synchrotron radiation (SR) to form an image of the beam. A model for calculating diffraction and depth of field effects is introduced. Assuming a Gaussian distributed electron beam, the relation between beam image size and actual beam size is then calculated with this model, for a number of practical measuring situations. In a series of measurements at the MAX I electron storage ring at a current of 1 mA, the beam image size has been measured for these calculated situations. The measured values are presented, and their behaviour is in good agreement with the model. With this model the horizontal and vertical rms beam sizes were determined to σx = (203 ± 3) μm and σy = (19 ± 3) μm respectively. The corresponding vertical emittance is approximately 0.05 nm rad.

The design of a 3 GHz thermionic RF-gun and energy filter for MAX-lab

A new pre-injector has been designed for the MAX-laboratory. It consists of an RF-gun and a magnetic energy filter. The newly designed RF-gun geometry will be operated at 3 GHz in the thermionic mode using a BaO cathode. The pre-injector will provide a 2.3 MeV electron beam in 3 ps micro pulses to a new injector system currently under construction

Experiences with the narrow gap undulator at MAX-lab

An undulator with short poles (period 24 mm) and extremely narrow gap (magnet gap 7.7 mm) using a squeezable vacuum chamber has been installed and is in operation at the MAX-lab 550 MeV storage ring. The device operates with a vacuum chamber aperture down to 6.2 mm. The behaviour of the storage ring concerning lifetime, emittance, tune shift and closed orbit is well described by conventional models. We present here the design of the device, the influence on the storage ring and the spectral characteristics, as well as comparison with expected theoretical results and an overview of the activities at the beam line.

The MAX IV Facility

The MAX IV facility is a planned successor of the existing MAX facility. The planned facility is described below. It consists of two new synchrotron storage rings operated at different electron energies to cover a broad spectral region and one linac injector. The linac injector is also meant to be operated as a FEL electron source. The two rings have similar low emittance lattices and are placed on top of each other to save space. A third UV light source, MAX III, is planned to be transferred to the new facility.

Observation of coherent synchrotron radiation from a 1-mm electron bunch at the MAX-I storage ring

The coherent generation of synchrotron radiation by an electron storage ring is predicted for wavelengths equal to or longer than the electron bunch length. With typical bunch lengths of approximately 1 cm, diffraction and chamber- screening effects have so-far blocked observation of coherent radiation from a conventional radiation beam line. In the low-energy, second-generation light source MAX-I, the magnet lattice has been tuned to a small momentum compaction factor, allowing rms bunch lengths as short as 1 mm. Here we report the coherent emission phenomena observed from such a bunch at the infrared beam line attached to the MAX-I ring.

EMITTANCE MANIPULATION BY FIRST- AND SECOND-ORDER LATTICE CONTROL

The lattice of the MAX-I electron storage ring has been investigated and tuned towards small momentum compaction values. By measurements of the synchrotron frequency, bunch length, horizontal beam size and beam movement, the beam has been found to behave in reasonable agreement with the predictions of the lattice model up to second order in energy deviation. Both longitudinal and horizontal emittance could be varied within a relatively large range with lattice changes and/or controlled beam energy changes.

The new 1.5 GeV storage ring for synchrotron radiation: MAX II

The MAX laboratory at Lund University, Sweden, today operates an accelerator system consisting of a 100 MeV racetrack microtron and a 550 MeV storage ring (MAX I). At the moment (July 1994) a new storage ring MAX II is near completion and will start first injections within 2 months. This work gives an overview of the MAX II project including the first beamlines and a description of the accelerator system. MAX II is a 1.5 GeV third generation light source optimized for the VUV and soft‐x‐ray region. It consists of a ten cell double bend achromat lattice forming the 90 m circumference ring. Injection is done at 500 MeV from the existing storage ring MAX I, and ramping up to full energy will take place in MAX II. The straight sections have a length of 3.2 m and eight sections are free to house insertion devices. At start up the ring will be equipped with one 7.5 T superconducting wiggler and one 1.8 T multipole wiggler. Two more undulators are ordered and under construction. To be able to achieve the project...