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.
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.
121398906
Generalized Fermi-Segrè formula
121322221
Correspondence between the classical and quantum canonical transformation groups from an operator formulation of the wigner function
An explicit expression of the “Wigner operator” is derived, such that the Wigner function of a quantum state is equal to the expectation value of this operator with respect to the same state. This Wigner operator leads to a representation-independent procedure for establishing the correspondence between the inhomogeneous symplectic group applicable to linear canonical transformations in classical mechanics and the Weyl-metaplectic group governing the symmetry of unitary transformations in quantum mechanics.
54512122
Bunch length beating in PLS storage ring
During the normal operation period in the Pohang Light Source (PLS) storage ring, the spontaneous bunch length oscillation or beating is generated by the nonlinear effects of the RF noise whose frequency is much lower than the bifurcation frequency. Due to the bunch length beating, we can not supply the uniform intensity beams to users. We have described the observed bunch length beating and its mechanism in the PLS storage ring with a simulation.
56039995
DEVELOPMENT OF BEAM PROFILE MONITOR FOR CYCLOTRON
A current sensor module was designed and fabricated to measure the beam profile of the cyclotron MC50 at KIRAMS. The sensors were made of a tungsten wire and they were assembled into an array type. The sensor wires were placed in parallel with the incident beam, while they were placed in the perpendicular direction to the incident beam in the conventional method. The current output of each sensor was amplified using a transresistance amplifier. The front-end stage of this amplifier was implemented using discrete circuit elements and can measure input current in the range of 1 pA to 1 μA. The amplifier had a resolution of ~ 20 fA and the temperature drift of ~ 0.5 pA/°C. Various test results of the amplifier and sensor module assembly are given in this paper. The measured current profiles of cyclotron beam line at KIRAMS are also given.
120440944
A simple method for illustrating the difference between the homogeneous and inhomogeneous Lorentz groups
A method is proposed for illustrating the difference between the Poincare (inhomogeneous Lorentz) and homogeneous Lorentz groups. Representations of the Poincare group are constructed from solutions of the relativistic harmonic oscillator equation whose physical wave functions have been effective in describing basic high‐energy hadronic features in the relativistic quark model. It is shown that the Poincare group can be represented by solutions of the relativistic oscillator equation in a ’’moving cylindrical’’ coordinate system in which the time‐separation variable in the hadronic rest frame is treated separately. Representations which are diagonal in the Casimir operators of the homogeneous Lorentz group are also constructed from solutions of the same oscillator differential equation in a hyperbolic coordinate system. It is pointed out that the difference between the Poincare and homogeneous Lorentz groups mainfests itself in the coordinate systems in which the oscillator differential equation in separable.