Structural changes in bunched crystalline ion beams (original) (raw)
Related papers
Spatial Compression of Bunched Crystalline Ion Beams
Physica Scripta, 2003
Recently, bunched crystalline ion beams have been realized in the table-top rf quadrupole storage ring PALLAS by means of laser cooling. Here, a novel method for the measurement of the spatial distribution of the ion bunch is presented which is based on the time-resolved analysis of the fluorescence emitted by the ions during cooling. Thus, the phase transition from a gaseous to a crystalline beam can be followed monitoring the whole phase space, and structural transitions can be studied as a function of the variable longitudinal confinement. Surprisingly, the length of crystalline bunches was found to be considerably shortened by a factor of three with respect to the length expected for space charge dominated bunches.
Storage of crystalline ion beams
Proceedings of the 2003 Particle Accelerator Conference, Vols 1-5, 2003
Recently, the phase transition of a low-energy ¾ Mg • ion beam into the Coulomb-ordered 'crystalline' state could be realized in the rf quadrupole storage ring PALLAS at the LMU Munich. Thereby, an increase of the phase space density of the beam, subjected to longitudinal laser cooling, by about six orders of magnitude was observed. In this paper, we focus on the systematic experimental investigation of the role of the focusing conditions and of bending shear in the storage ring on the attainment of crystalline beams of different crystal structure.
The quest for crystalline ion beams
Plasma Physics and Controlled Fusion, 2002
The phase transition of an ion beam into its crystalline state has long been expected to dramatically influence beam dynamics beyond the limitations of standard accelerator physics. Yet, although considerable improvement in beam cooling techniques has been made, strong heating mechanisms inherent to existing high-energy storage rings have prohibited the formation of the crystalline state in these machines up to now. Only recently, laser cooling of low-energy beams in the table-top rf quadrupole storage ring PAaul Laser cooLing Acceleration System (PALLAS) has lead to the experimental realization of crystalline beams. In this article, the quest for crystalline beams as well as their unique properties as experienced in PALLAS will be reviewed.
Feasibility of a crystalline condensed state in cooled ion beams of a storage ring
European Physical Journal A, 1988
The conditions under which an ordered system of particles could be achieved in a storage ring have been studied with Molecular Dynamics calculations. Potential problems associated with periodic focusing, out of phase focusing in two directions, and of shear associated with the closed orbits in the ring have been modelled in the MD calculations and the qualitative effects of these perturbations are assessed. The results are related to storage rings under construction and to the measurements that had been carried out at Novosibirsk.
1997
After the successful exploitation of electron cooling in several heavy ion storage rings the possibility of generating crystalline ion beams gained the interest of particle accelerator physicists. New cooling methods, such as laser cooling, give further opportunity to reach ultra cold system of particles necessary for the state transition to the crystalline configuration. Crystalline beams will give insight into a
Optical measurement of the longitudinal ion distribution of bunched ion beams in the ESR
Nuclear Instruments & Methods in Physics Research Section a-Accelerators Spectrometers Detectors and Associated Equipment, 2013
An optical technique to study the longitudinal distribution of ions in a bunched ion beam circulating in a storage ring is presented. It is based on the arrival-time analysis of photons emitted after collisional excitation of residual gas molecules. The beam-induced fluorescence was investigated in the ultraviolet regime with a channeltron and in the visible region using a photomultiplier tube. Both were applied to investigate the longitudinal shape of bunched and electron-cooled 209 Bi 80 þ ion beams at about 400 MeV/u in the experimental storage ring (ESR) at GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. Bunch lengths were determined with an uncertainty of about 0.5 m using the UV-sensitive channeltron and with slightly lower accuracy from the photomultiplier data due to the slower transitions in the red region of the spectrum. The Gaussian shape of the longitudinal distribution of ions inside the bunch was confirmed. With the information of the transverse beam size that can be measured simultaneously by a newly installed ionization profile monitor (IPM) at the ESR, an accurate determination of the ion density in the bunched beam will be allowed.
Longitudinal dynamics of RF-bunched and electron-cooled ion beam at the CSRe
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2014
The longitudinal dynamics of RF-bunched and electron cooled ion beams have been studied at the experimental cooler storage ring (CSRe), at IMP Lanzhou. By RF-bunching the ion beam at the 50th and 100th harmonic of the revolution frequency, the longitudinal momentum spread and the bunch length of the 22 Ne 10 þ ion beam with an energy of 70 MeV/u were measured by the new resonant Schottky pickup and the capacitive pickup , respectively. A minimum momentum spread of Δp=p ¼ 1:6 Â 10 À 5 has been reached with less than 10 7 ions stored in the ring. By using the harmonic potential extracted from the Taylor expansion and the real sinusoidal potential of the bucket, the trend of momentum spread and synchrotron frequency as well as the bunch length as a function of beam current can be interpreted very well. According to this experiment, the RF-buncher is suitable for upcoming experiments on laser cooling of relativistic heavy ion beams at the CSRe.
The storage ring Super ACO at Orsay offers a large agility as regards the value of the momentum compaction factor (α), i.e., under special conditions α can be set to either positive, negative or very small values. This aspect can be important for the development of new Storage-Ring (SR) based light-sources where a high electrondensity is advantageous. Recently, the influence of α on the micro-bunch length and the energy-spread was investigated experimentally. The diagnostics are described in detail. Results, regarding the influence of the average beam current and α on the bunch-length and energy spread, are discussed.
DESIREE: a unique cryogenic electrostatic storage ring for merged ion-beams studies
Journal of Physics: Conference Series, 2011
In this proceedings I will describe the design of a new storage device currently under construction at Stockholm University, Sweden. This device uses purely electrostatic focussing and deflection elements and allows ion beams of opposite charge to be confined under extreme high vacuum and cryogenic conditions in separate "rings" and then merged over a common straight section. This Double ElectroStatic Ion Ring ExpEriment (DESIREE) apparatus allows for studies of interactions between cations and anions at low and well-defined centre-of-mass energies. I discuss the design of the DESIREE facility, highlighting some of the technical advantages of using purely electrostatic over magnetic elements, as well as the issues that have arisen during its development and construction. Finally, the advantages of this design are a boon to fundamental experimental studies and I finish by discussing an example of such potential research.