RF System Upgrades to the Advanced Photon Source Linear Accelerator in Support of the Fel Operation

The S-band linear accelerator, which was built to be the source of particles and the front end of the Advanced Photon Source injector, is now also being used to support a low-energy undulator test line (LEUTL) and to drive a free-electron laser (FEL). The more severe rf stability requirements of the FEL have resulted in an effort to identify sources of phase and amplitude instability and implement corresponding upgrades to the rf generation chain and the measurement system. Test data and improvements implemented and planned are describedComment: LC 2000 (3 pages, 6 figures

Testing and Implementation Progress on the Advanced Photon Source (APS) Linear Accelerator (Linac) High-Power S-band Switching System

An S-band linear accelerator is the source of particles and the front end of the Advanced Photon Source injector. In addition, it supports a low-energy undulator test line (LEUTL) and drives a free-electron laser (FEL). A waveguide-switching and distribution system is now under construction. The system configuration was revised to be consistent with the recent change to electron-only operation. There are now six modulator-klystron subsystems, two of which are being configured to act as hot spares for two S-band transmitters each, so that no single failure will prevent injector operation. The two subsystems are also used to support additional LEUTL capabilities and off-line testing. Design considerations for the waveguide-switching subsystem, topology selection, control and protection provisions, high-power test results, and current status are describedComment: Linac 2000 paper No. THE07 3 pages with 3 figure

Design and testing of a high power, ultra-high vacuum, dual-directional coupler for the Advanced Photon Source (APS) linear accelerator

Leaks and cracks have developed in the vacuum windows of the linac WR 284 waveguide directional couplers. In the existing coupler design the vacuum window is brazed to the waveguide. Replacement of a cracked window requires the removal of the component from the waveguide system resulting in a loss of vacuum in the waveguide. A new design has been developed and a prototype tested that utilizes bolted-in vacuum windows and allows for easier replacement of the windows in the system, while still providing suitable radio frequency (rf) specifications

A high peak power S-band switching system for the Advanced Photon Source (APS) Linear Accelerator (Linac).

An S-band linear accelerator is the source of particles and front end of the Advanced Photon Source [1] injector. Additionally, it will be used to support a low-energy undulator test line (LEUTL) and to drive a free-electron laser (FEL). To provide maximum linac availability for all uses, an additional modulator-klystron subsystem has been built,and a waveguide-switching and distribution subsystem is now under construction. The combined subsystems provide a hot spare for any of the five S-band transmitters that power the lina cand have been given the additional function of powering an rf gun test stand whenever they are not otherwise needed. Design considerations for the waveguide-switching subsystem, topology selection, timing, control, and system protection provisions are described

RF and Beam Diagnostic Instrumentation at the Advanced Photon Source (APS) Linear Accelerator (Linac)

A system of beam diagnostics and rf phase and amplitude measurement, based mostly on VXI, was implemented at the APS Linac and has now operated successfully for more than two years. Standardization of instrumentation among the various APS accelerators accounted for some of the non-VXI packaged equipment that was used. Equipment for which the optimum topology or location did not lend itself to VXI was also accommodated so as to yield the greatest stability, reliability, and flexibility. The APS Linac instrumentation is described, and operational performance is discussed. Future plans, including an expansion to include a switchable spare klystron (which can be accommodated with only minor changes to the VXI-housed equipment) and a beam position monitor using frequency domain analysis to provide improved determination of positron position in a mixed-particle beam condition are also discussed

Ii. System Description

Rf power for the APS linear accelerator is provided by five klystrons, each of which feeds one linac "sector," containing accelerating structures and SLED cavities. A VXI-based subsystem measures the phase of each sector of the linac with respect to a thermally stabilized reference line. The resulting information is used to control a linearized varactor phase shifter. Error correction is done by software, using operatorcontrollable parameters. A second phase shifter provides an intra-pulse correction to the phase of the klystron drive pulse. When the intra-pulse correction is applied, the resulting phase is flat to within 0.5 after 2.5 sec. A second correction, made after the PSK trigger to the SLED and during the filling of the accelerating structures, resulted in an energy gain of 5 MeV from a single sector. I. INTRODUCTION The rf schematic for the APS linac is shown in Figure 1. Linac sectors are comprised of a klystron and associated accelerating structures. Figure 1: Schematic ..

Construction, Commissioning and Operational Experience of the Advanced Photon Source (APS) Linear Accelerator

Abstract The Advanced Photon Source [1] linear accelerator system consists of a 200-MeV, 2856-MHz S-band electron linac and a 2-radiation-thick tungsten target followed by a 450-MeV positron linac. The linac system has operated 24 hours per day for the past year to support accelerator commissioning and beam studies and to provide beam for the user experimental program. It achieves the design goal for positron current of 8 mA and produces electron energies up to 650 MeV without the target in place. The linac is described and its operation and performance are discussed