Design of a low-emittance 2.5-GeV pohang light source lattice
The Pohang Light Source (PLS) storage ring is a synchrotron light source with the emittance of 18.9 nm at 2.5 GeV. We designed a new lattice with an achromat of the emittance of 13 nm that may provide more brilliant synchrotron radiation. We investigated dependence of the dynamic aperture on the betatron tune to search for large dynamic aperture in the low-emittance lattice by a simulation method. We examined the dynamic apertures by a tune survey within a specified tune space without and with machine errors. It is also shown that how large is the dynamic aperture in the storage ring after correction of a closed orbit distortion. The operating tune for the low-emittance lattice can be chosen on the view point of dynamic apertures obtained from a tune survey. The low-emittance lattice with the achromat shows the reduced horizontal and vertical beam sizes by 10% and 29% in the positions of insertion devices and by 31% and 52% in the bending magnets than the present lattice, respectively. It is also shown that the low-emittance lattice with 13 nm may provide sufficient dynamic aperture without changing of configuration of magnets in the storage ring.
Commissioning and performance of the Advanced Light Source
The Advanced Light Source (ALS) at the Lawrence Berkeley Laboratory is the first of the lower energy (1 to 2 GeV) third-generation synchrotron radiation facilities to come into operation. Designed with very small electron beam emittances, to operate with long insertion devices to produce very high brightness beams of synchrotron radiation in the VUV and soft X-ray regions of the spectrum, these facilities are complementary to the higher energy (6 to 9 GeV) facilities designed for harder X-radiation. From the earliest periods of their design it was recognized that the performance of the required low-emittance lattices would be dominated by nonlinear particle dynamics caused by the strong lattice sextupoles required for chromatic correction, the effects of undulators and wigglers, and the requirement for very narrow-gap vacuum vessels. Commissioning of the ALS storage ring began early in 1993. In this paper we will briefly review the main characteristics of the storage ring design, describe our commissioning experiences, and review the present performance and performance limitations of the facility.<<ETX>>
Coherent pulsed injection seeding of two gain-switched semiconductor lasers
High-power, narrow-spectrum, short pulses at a wavelength near 830 nm are needed for optical logic applications. The authors report the generation of two coherent trains of pulses by pulsed injection seeding of two gain-switched semiconductor lasers with one mode-locked master oscillator. The available power was doubled and both lasers emit in nearly identical spectral lines. Short pulses (30-50 ps) are generated at a repetition rate of 1.9 GHz. The spectrum is reduced to a single mode cluster and shows a 1.7 AA wide chirp suitable for pulse compression. The peak power is 0.1 W for each pulse train. The capability of this technique for coherent power combining is demonstrated.<<ETX>>