Correction Of Closed Orbit Distortion Research Articles

Design and optimization of a multi-bend achromat lattice for 3.5 GeV synchrotron storage ring

In the past decades, the optimized design of light source array by use of multi-bend achromat has been considered to achieve high-quality photon beam for fundamental researches in different areas of science and technology. In this paper, we investigate a lattice design for a low emittance storage ring with intermediate energy of 3.5 GeV . We present the design results in detail for a five-bend achromat lattice with an emittance of 230 pm-rad, appropriate dynamic aperture, high brilliance photons near soft X-ray diffraction limited, the total lifetime of 11 hours and circumference of 448 m contains 20 straight sections of 6.1 meters in length. The results of closed orbit correction and misalignments errors on the dynamic aperture were also presented. The lattice provides sufficient dynamic aperture after closed orbit distortion correction. Furthermore, the variation of the emittance due to coupling and intra-beam scattering (IBS) effect has been calculated as a function of the energy and length of the bunch. Our designed storage ring shows an optimized five-bend achromat lattice for intermediate light sources.

Beam based alignment and its relevance in Indus-2.

Initially in the Indus-2 storage ring, the closed orbit distortion (COD) could be best corrected to 1.3 mm rms in the horizontal and 0.43 mm rms in the vertical plane. The strength of the corrector magnets required high values for COD correction. This revealed that offsets in COD readout by the beam position monitors (BPMs) played a role in not achieving a rms COD lower than the above value. Thus, the offset between the electrical center of BPMs and the magnetic center of the nearest quadrupole magnet could be estimated using the beam based alignment (BBA) method. It prefers that the quadrupole magnet is able to be controlled individually and active shunt power supply (ASPS) system was designed for this purpose that works efficiently. This paper describes the methodology of BBA, topology of ASPS and its performance, and COD minimization using the measured BPM offsets. After BBA, the COD could be reduced to 0.45 mm rms and 0.2 mm rms in horizontal and vertical planes, respectively.

Design of a low-emittance lattice for 3.5 GeV synchrotron light source

We investigate a lattice design for a low-emittance, high-brilliance intermediate energy synchrotron light source that is being intensively performed in the world. We present the design results in detail for a non-achromatic double bend achromat lattice with an emittance of 1.1 nm and 597.6 m circumference. Each superperiod has 4 straight sections, 7 m, 5.4 m, and 2 × 2.8 m in length, giving a total of 60 straight sections in the ring. The lattice is designed to be flexible and also provides an achromatic optics with an emittance of 3.2 nm. The lattice provides high brilliance at a photon energy of a few tens of keV, which meets the requirements of hard X-ray synchrotron radiation users. We investigated the dynamic aperture in the lattice with machine errors using a simulation method that achieves the optimal tune for the ring. The low-emittance lattice provides sufficient dynamic aperture after closed orbit distortion correction. We show an estimate of variations of emittance, energy spread, and dynamic aperture due to a wiggler in the straight sections. We present the design of an injection scheme for full energy injection, the space allocation in injection section, and the particle dynamics of injected beam. Particle tracking after beam injection was performed to examine the validity of the injection scheme. Our design lattice shows good optimization in terms of the emittance, number of straight sections, brilliance, and circumference as a light source for 3.5 GeV beam energy.

Measurement, analysis and correction of the closed orbit distortion in Indus-2 synchrotron radiation source

The paper presents the measurement, analysis and correction of closed orbit distortion (COD) in Indus-2 at 550 MeV injection energy and 2 GeV synchrotron radiation user run energy. The measured COD was analysed and fitted to understand major sources of errors in terms of the effective quadrupole misalignments. The rms COD was corrected down to less than 0.6 mm in both horizontal and vertical planes. A golden orbit was set for the operating synchrotron radiation beamlines. With COD correction, the injection efficiency at 550 MeV was improved by ~50% and the beam lifetime at 2 GeV was increased by ~8 h. In this paper, the method of global COD correction based on singular value decomposition (SVD) of the orbit response matrix is described. Results for the COD correction in both horizontal and vertical planes at 550 MeV injection energy and at 2 GeV synchrotron radiation user run energy are discussed.

COD correction for laser cooling at S-LSR

A closed orbit is corrected for single-turn injection to perform laser cooling experiments of 40 keV 24 Mg + beam at the small laser-equipped storage ring (S-LSR). Closed orbit distortion (COD) corrections have been carried out using a downhill simplex method, and CODs of less than ± 0.5 mm have been achieved throughout the whole circumference. The injection orbit and the CODs are optimized to pass through the two aperture holes in the alignment targets located in the laser cooling section with an algorithm to maximize beam lifetime. The CODs at the aperture holes are reduced to be less than ± 0.2 mm , assuring an overlap between the laser and the 24 Mg + ion beam.

Beam position monitoring system and COD correction at the cooler synchrotron TARN II

At the cooler-synchrotron TARN II, light- and heavy-ion beams are stored, electron-cooled and accelerated for the research of atomic physics and accelerator studies. In these experiments, the closed orbit distortion (COD) correction system plays an important role for improving the beam currents and lifetimes. In order to measure the position of a circulating faint beam in the ring, we developed beam diagnostic devices of high sensitivity and low noise. The beam positions can be measured with an accuracy of 0.3 mm at a circulating beam current of 1 μA. It is the purpose of the present paper to describe details concerning the beam position monitor (BPM) system, an investigation of the sensitivities of the BPM from the point of view the S N ratio, the experimental results of a COD correction and measurements of the accelerator parameters, such as the chromaticity and dispersion using this system.