16754660
DEVELOPMENT OF THE SIMULATOR FOR THE GLOBAL ORBIT FEEDBACK SYSTEM USING EPICS
We have carried out the basic research for the accelerator and tokamak control system based on the Experimental Physics and Industrial Control System (EPICS). We have used the process database and the state notation language (SNL) in the EPICS to develop the simulator which represents as a virtual machine. In this paper, we introduce the simulator of the global orbit feedback system as an example. This simulates the global orbit feedback system under the constraint conditions for Pohang Light Source (PLS) storage ring. We describe the details of the feedback algorithm and the realization of the simulator.
11157984
Growth time of the longitudinal coupled bunch mode beam instability at the Duke FEL facility
To determine the required power of an amplifier for the longitudinal feedback (LFB) system, the growth time of the strongest longitudinal coupled bunch mode instability (CBMI) in the Duke storage ring should be measured in advance. In 2005, we measured strength of the strongest longitudinal beam instability in the Duke storage ring with four and eight symmetrically filled buckets. By analyzing measured data, the growth time of the strongest dipole mode of the longitudinal CBMI in the Duke storage ring can be estimated. At a beam energy of 274 MeV, the growth time is about 0.365 ms for a total stored beam current of 160 mA. From the measured growth time, we estimated the required power of the amplifier for the LFB system. To damp all harmful longitudinal CBMIs with an energy deviation of 0.1 % (rms) within its growth time of 0.365 ms, we have to supply about HOW (rms) to an LFB kicker whose a central frequency is 937.3875 MHz. In this paper, we describe the growth time of the longitudinal CBMI at the Duke storage ring and the estimation of the required power for the LFB system to damp all CBMIs within 0.365 ms.
67811641
ENERGY SPREAD ISSUE IN LASER UNDULATOR BASED XFELs
At the Center for the Exploration of Energy and Matter (CEEM) in Indiana University, we have been developing a new XFEL concept, which is based on inverse Compton scattering and a laser undulator instead of the conventional magnetic undulator. In this paper, we report an estimation of the energy spread growth in the electron storage ring due to the inverse Compton scattering itself and their impacts on the FEL lasing in the laser undulator based XFEL concept.
121093451
Stable operation of a self-amplified spontaneous-emission free-electron laser in the extremely ultraviolet region
43997367
New generation digital longitudinal feedback system for Duke FEL and HIγS facilities
To cure harmful longitudinal coupled-bunch mode beam instabilities during high-current and multi-bunch beam operations at the Duke free electron laser (FEL) and high intensity gamma-ray source (HIgammaS) facilities, we have been developing a new generation digital bunch-by-bunch longitudinal feedback (LFB) system which is based on an Integrated gigasample processor (iGp-64F). In this paper, we describe the new generation digital longitudinal feedback system for the Duke FEL and HIgammaS facilities.
55217395
DESIGN OF INJECTION AND EXTRACTION BEAMLINES FOR THE ALPHA PROJECT
The ALPHA facility consists of an electron linac and an electron storage ring to provide uniform intense beams for radiation test, and it has a potential to be a future X-Ray source. The ring uses four dipoles from the Cooler Injection Synchrotron (CIS) [1], which was constructed for proton acceleration from 7 MeV to 240 MeV. The circumference of the ALPHA storage ring is 20 m, and its lattice has an adjustible momentum compaction factor by changing the field strength of a pair of gradient damping wigglers [2]. For the proof of working principles, we use a refurbished 20 MeV CLINAC as the injector. The CLINAC will be upgraded to a 50 MeV linac by the end of 2011. Two operation modes (debunching and accumulation modes) [3] are currently planned for the ALPHA facility. For the debunching mode, two magnetic kickers are located at symmetric positions with respect to the Lambertson magnet. When the magnetic kickers are turned at 24 mrad, the closed orbit of the storage ring passes through the Lambertson magnet, and thus the injected beam is extracted in a single pass. In this case, the storage ring can be considered as a big α– magnet for debunching. For the beam accumulation mode, the magnetic kicker’s power supply is designed to have 500 ns decay time (beam revolution time in ring is 66 ns). The closed orbit is gradually moved back to designed orbit during injection so that multi-turn accumulation can be achieved in this way. In this paper, we describe the design concepts of the injection and extraction beamlines to maximize beam transport and to satisfy desired beam properties.
18064237
The effect of kaon condensation on quark-antiquark condensate in dense matter
Abstract Assuming that at sufficiently high densities the constituent quarks become relevant degrees of freedom, we study within the framework of a chiral quark model the influence of s -wave K − condensation on the quark–antiquark condensates. We find that, in linear density approximation, the presence of a K − condensate quenches the u ¯ u condensate, but that the d ¯ d condensate remains unaffected up to the chiral order under consideration. We discuss the implication of the suppressed u ¯ u condensate for flavor-dependent chiral symmetry restoration in dense matter.
119889363
Symmetries of two‐mode squeezed states
It is known that the symmetry of two‐mode squeezed states is governed by the group Sp(4) which is locally isomorphic to the O(3,2) de Sitter group. It is shown that this complicated ten‐parameter group can be regarded as a product of two three‐parameter Sp(2) groups. It is shown also that two coupled harmonic oscillators serve as a physical basis for the symmetry decomposition. It is shown further that the concept of entropy is needed when one of the two modes is not observed. The entropy is zero when the system is uncoupled. The system reaches thermal equilibrium when the entropy becomes maximal.
120290177
Covariant Harmonic Oscillators and Excited Baryon Decays
We use the covariant harmonic oscillator wave functions to study the decay matrix elements of the excited baryonic resonances. It is pointed out that the harmonic oscillator wave function is suitable for the description of relativistic extended particles. We use the probability concept of the covariant harmonic oscillator wave functions and the covariant Dirac spinors to calculate the Jrr decays of the F,. (1690), D,. (1690) and D,. (1520) resonances. Our numerical results are in good agreement with the measurable ratios in these decay processes.
110777646
The Pohang light source
A 2 GeV synchrotron light source project is in progress in Pohang, Korea. The light source is designed to provide high brightness radiation with continuous wavelengths down to 1 A (10-8 em) with its peak at 4·43 A(Le. 2·8 keY). The project, consisting of a full energy injector linear accelerator and a 2 GeV storage ring, was launched in 1988 and is scheduled to be completed by the end of 1994. In this article, we introduce the main features and status of the storage ring components and the installation procedure. Radiation characteristics and beamline status are also described.
73541758
PLS RF system operation during the commissioning
The storage ring of the Pohang Light Source (PLS) is designed to store 100s mA of 2 GeV electrons injected from the full energy linear accelerator. To compensate for the synchrotron radiation loss three RF cavities were installed in one of the straight sections powered by three 60 kW-TV transmitters independently. Phase and amplitude are controlled by the separate low level systems. During the commissioning, since the beam lifetime is limited by the vacuum pressure, various accelerating voltages were set to investigate the system characteristics. Even one cavity is enough to store 100 mA of beam, whereas the vacuum-limited lifetime is few minutes at 1 mTorr. The cavity HOM-induced multi-bunch instabilities were observed at certain condition and cured to some extent by shifting phase and water temperature. General description of RF system performance and trouble-shoots during the commissioning are presented.