The Advanced Photon Source High-Power Radio Frequency Test Stand

G. Pile and D. Horan

Accelerator Systems Division, Argonne National Laboratory

A high-power radio frequency (rf) test stand has been designed and constructed at the Advanced Photon Source (APS) for development and testing of 352-MHz rf high-power components. A shielded test bunker with a controlled-access monitoring system provides personnel protection. The facility is versatile and can be used to test a wide variety of rf components, including single-cell and five-cell rf cavities as presently used in the APS booster and storage ring, and associated couplers, tuners, and higher order mode dampers. The patchbay-style, low-level rf system allows for rapid configuration of rf monitoring and control electronics. It includes two complete cavity tuner control systems and a programmable controller providing complete flow, temperature, monitoring and interlock functions for the device being tested. Full Experimental Physics and Industrial Control System monitoring of all test parameters is provided. The RF Group expects to utilize this facility for future projects including superconducting rf cavity experiments and possible collaborative development work for Argonne National Laboratory-related projects such as the Rare Isotope Accelerator.

Beamline Electronics Developments

S. Ross

Accelerator Systems Division, Argonne National Laboratory

We discuss the support that the Accelerator Systems Division is providing to assist beamline science and APS collaborative access teams by developing various levels of beamline electronic instrumentation. This work ranges from simple circuitry that fits small niche needs, to electronic systems that support an overall experiment with complex x-ray detector systems. The work is coordinated with other APS groups in all three APS divisions, with projects being largely customer driven, in that we try to respond to direct requests for help from beamline staff. However, we also try to focus on systems that can benefit multiple beamlines. We will discuss several example systems, including a picoamp-level quad electrometer system useful for beam position and intensity monitoring.

Advanced Photon Source Support for Rare Isotope Accelerator Pre-CD0 Planning

J. Noonan

Accelerator Systems Division, Argonne National Laboratory

Advanced Photon Source (APS) staff are providing engineering support for Rare Isotope Accelerator (RIA) planning and development in several ways. Engineers are designing prototypes for RIA Laboratory Directed Research and Development (LDRD) work projects and a team of four Accelerator Systems Division (ASD) staff members worked with the RIA Planning Division this summer to prepare engineering estimates for the baseline project. This work was supported by LDRD funds; the engineering estimation effort was charged to the RIA Planning Division.

Sushil Sharma (ASD-ME) is working with Petr Ostroumov (PHY) to design and fabricate low-power prototypes of the 12-MHz hybrid radio frequency quadrupole (RFQ) for the radioactive ion beam (RIB) accelerator. In 2004, full-power, copper prototypes of the RFQ and the hybrid RFQ will be fabricated. Also in 2004, Bob Lill (AOD-DIA) will work Ostroumov to design and test prototypes of diagnostics equipment that will be used in the RIA driver linac and the RIB accelerator.

Jim Lang (ASD-ESH), Phil McNamara (ASD-ES), John Noonan (ASD-ADM), and Terry Smith (ASD-RF) were temporarily assigned to the RIA Planning Division to perform an engineering cost plan for the baseline RIA facility. The ASD team developed engineering cost estimates for the RIA magnets, power supplies, electrical utilities for the accelerator, rf, and the mechanical and vacuum systems. Evaluation of environment, safety, and health requirements and wetland mitigation plans were also developed. The ASD engineers also reviewed the accelerator enclosures and the accelerator support facilities. In 2004, ASD engineers will continue to work with RIA to revise the baseline plan to include a number of accelerator enhancements, such as triple-spoke resonators, increased packing factors for the low- and medium-beta linacs, and the isotope fragmentation enclosure.

Coordinated Accelerator Research at Argonne National Laboratory (CARA)

K.-J. Kim

Accelerator Systems Division, Argonne National Laboratory

Argonne National Laboratory has a number of accelerators (Advanced Photon Source, Intense Pulsed Neutron Source, Argonne Tandem Linear Accelerator System, Argonne Wakefield Accelerator) and Argonne researchers are interested in involvements with other accelerators, both as users and accelerator developers (e.g., Rare Isotope Accelerator, Linear Collider).

Coordinated Accelerator Research at Argonne National Laboratory (CARA) was set up to coordinate activities related to these interests. The focus has been to identify Argonne core expertise and align it with prioritized needs in the accelerator community.

In addition to improving communication and collaboration within Argonne National Laboratory, CARA has provided a centralized point of contact within the Laboratory for collaborations with other organizations (e.g., Fermilab and area universities). There is presently a working group that is identifying organizational and strategic plans for a regional center for accelerator R&D, presently called the Institute for Advanced Accelerator Physics.

This poster will present the status of CARA and the developing collaborations with Fermilab and area universities.

A Summary of Advanced Photon Source Radio Frequency Components Modeling and Development Activities

G. Waldschmidt and L. Morrison

Accelerator Systems Division, Argonne National Laboratory

The Advanced Photon Source (APS) at Argonne National Laboratory is a national user facility constructed by the U.S. Department of Energy for synchrotron x-ray research. It is a third-generation synchrotron radiation source specifically designed to accommodate insertion devices and operate beamlines from bending magnet radiation sources. The storage ring is designed to operate at 7 GeV with a full-energy electron injector. The injector/booster synchrotron consists of a single 1-MW klystron which drives four 5-cell cavities at 352 MHz. The storage ring cavities consist of four groups of four single-cell cavities, powered by two 1-MW klystrons for 100-mA operation, with an additional 1-MW klystron ultimately needed to reach the design goal of 30 0mA at 7 GeV.

Improvements and upgrades to the radio frequency (rf) systems are necessary in order to achieve greater operational reliability and increased accelerator performance. To improve reliability, an analysis of the failures of the ceramic in the high-power-input couplers for the storage ring rf cavities, as well as overheating in the tuners due to modal high-frequency energy, is investigated. In addition, the implementation of higher order mode dampers into the storage ring rf cavities will improve longitudinal beam stability and enhance the quality of the beam available to users.

Real-Time Feedback

F. Lenkszus

Accelerator Systems Division, Argonne National Laboratory

The real-time feedback system’s primary purpose is to globally reduce dynamic orbit perturbations above 0.1 Hz. The system consists of 21 distributed input/output controllers with a total of 80 processors communicating over a dedicated 29.5-Mbytes/second network. It operates at an iteration rate of 1534 Hz and uses 160 beam position monitors and 38 correctors. The theory of operation, system features, and results will be presented.

Experimental Physics and Industrial Control System Development: Past, Present, and Future

N. Arnold1, A. Johnson1, M. Kraimer1, J. Maclean2, and E. Norum1

1 Accelerator Systems Division, Argonne National Laboratory
2 APS Operations Division, Argonne National Laboratory

The real-time control system at the Advanced Photon Source (APS) is based on the Experimental Physics and Industrial Control System (EPICS) software toolkit, which was developed as a collaboration between Los Alamos National Laboratory (LANL) and the APS beginning in 1990. Since then, EPICS has grown in popularity among accelerator laboratories, telescope facilities, and even for commercial applications and has become globally recognized as a capable, robust, and flexible platform on which to build a control system. There are currently over 130 licensed users of the EPICS software, with many large Department of Energy facilities among them (e.g., APS, Intense Pulsed Neutron Source, Brookhaven National Laboratory. Stanford Linear Accelerator Center, Lawrence Berkeley Laboratory, Fermilab, Thomas Jefferson National Accelerator Facility, Princeton Plasma Physics Laboratory, Sandia National Laboratories, Spallation Neutron Source, etc.). Most beamlines at the APS, and numerous beamlines at other light sources (14 at the National Synchrotron Light Source) also use EPICS as the solution for beamline control. EPICS has a wide international user base as well, including the KECK and Gemini telescopes, Berliner Elektronenspeicherring — Gesellschaft für Synchrotronstrahlung, the Swiss Light Source, the Canadian Light Source, the Diamond Light Source, and the KEK accelerator facility. The APS continues to be a major contributor to EPICS and is directly involved with EPICS development, distribution, coordination, and documentation.

EPICS, like all other accelerator technologies, must continually advance in order to meet the needs of future accelerators. Two recent efforts that demonstrate the commitment of the EPICS collaboration to keep EPICS current are described below.

1. Beginning with EPICS Release 3.14 (currently available), the real-time portion of EPICS (known as iocCore) can now run on many different computer operating system platforms. This capability allows for the use of low-cost computing platforms, making EPICS even more attractive for small installations, such as individual beamlines. While this greatly increases the flexibility of EPICS by allowing developers to choose their own computer platforms, it also substantially increases the effort needed to develop and support these diverse platforms.

2. Recently, an international task force was formed to investigate and propose the long-term enhancements to EPICS necessary for it to remain a viable product for the next 7 to 10 years. Undoubtedly, these suggestions from the "EPICS 2010" committee will require substantial resources to implement.

Storage Ring Lattice Calibration and Control

V. Sajaev

Accelerator Systems Division, Argonne National Laboratory

The APS storage ring is a complicated machine containing 400 quadrupoles and 280 sextupoles, each powered separately. The quadrupole calibration errors and orbit errors through the sextupoles are two main sources of linear optics distortion. The linear optics of the storage ring has been experimentally determined using an orbit response matrix analysis. The results obtained were used to correct the β-function beating around the ring. These corrections significantly improved the beam lifetime and injection efficiency. Thorough calibration of the optics allows us to efficiently control and modify the lattice.

The Advanced Photon Source Injector Test Stand

S. Berg and J. Lewellen

Accelerator Systems Division, Argonne National Laboratory

The Injector Test Stand (ITS) began to take shape shortly following commissioning of the Advanced Photon Source (APS) in 1996. The north wall of the room is the original poured concrete wall that was once a part of the linac tunnel, while the south wall is constructed from density-enhanced concrete shielding blocks, effectively separating the test room from the gun end of the linac tunnel. In 2001, the ITS was used to commission three second-generation thermionic-cathode radio frequency guns. Two of the guns are installed in the APS linac, while the third acts as a “shelf spare” for the APS. The ITS also serves as an Operator Training Facility, where the “look and feel” of the APS linac control screen systems and the control screen for the injector test stand beamline are similar; all operations, including data collection and process automation, are identical. The ITS provides a location where almost any accelerator-related hardware can be tested with beam before installation. Currently configured to investigate performance of the prototype ballistic bunch compression gun, measurements performed using the ITS in August of 2003 yielded the first actual characterization of the gun’s performance. These experimental results were extremely well matched the theoretical bunch compression characteristics.

Raising the Single-Bunch Current Limit in the Advanced Photon Source Storage Ring

Y.-C. Chae

Accelerator Systems Division, Argonne National Laboratory

One of long-term goals in operating the Advanced Photon Source (APS) storage ring is raising the single-bunch current limit. This task requires a deep understanding of coherent instabilities. Various instabilities were observed in the APS storage ring in past years. Some had been mitigated, but some of them need further investigation for better understanding. These include transverse saw-tooth instabilities, anomalous bunch lengthening, and vertical mode-coupling instability caused by small-gap chambers. We take a three-step approach to dealing with instability issues associated with raising the single-bunch current limit: 1) obtain detailed knowledge of the impedance in the ring through the Impedance Database concept developed at the APS, 2) explain and reproduce the collective phenomena observed in the ring via multi-particle simulation, and 3) propose and implement specific methods to raise the single-bunch current limit. In this poster we present the progress made in all three areas, including the proposed injection optimization, which would not only reduce injection loss but also increase the single-bunch current limit.

Power Supply Availability Improvements

J. Wang and T. Fors

Accelerator Systems Division, Argonne National Laboratory

The Accelerator Systems Division Electrical Systems Group tracks power supply reliability in a number of ways. Among these, the two most meaningful measures to Advanced Photon Source (APS) users are down time and fault rate. While power supply downtime goals have consistently been met for the past two years, meeting the fault-rate goal has been more challenging. There are nearly 1500 magnet power supplies in the storage ring alone, and failure of any one the 1500 can bring down stored beam. With such a large number of power supplies, reducing the fault rate necessitates very high reliability from each individual power converter. This requires a robust design, high-quality workmanship, and proactive maintenance in order to achieve high reliability. We are actively addressing each of these aspects and anticipate power supply reliability to continue to improve as a direct result of upgrades, quality control, and preventative maintenance plans. Reliability data presented here include improvements resulting from the very successful control power upgrade.

Vacuum Ultraviolet Free-Electron Laser and Experiments

J. Lewellen1 and M. Pellin2

1 Accelerator Systems Division, Argonne National Laboratory
2 Materials Science Division, Argonne National Laboratory

There exists at the Advanced Photon Source (APS) a functional free-electron laser (FEL) system proven capable of sustained operation over a tunable wavelength range from deep in the red at 660 nanometers to 120 nanometers in the vacuum ultraviolet (VUV) wavelength range. This FEL is at present the only laser system in the world capable of providing intense light pulses tunable in the VUV, making it an extremely unique source that will enable science not possible anywhere else. Coupled to this laser source is a state-of-the-art scientific apparatus, the SPIRIT detector (Single Photon Ionization and Resonant Ionization to Threshold). Together this FEL/detector system can explore a very wide range of science, from the determination of isotopic abundances in stellar material via resonant ionization, to threshold mass spectrometry, to using single photon ionization of molecular species in looking for modified DNA material that may be a precursor to cancer. The wavelength tunability of this source and the high energy per pulse make this possible.

The APS FEL program was built upon and heavily leveraged the existing APS linear accelerator, APS undulator systems, and APS infrastructure to operate the first self-amplified spontaneous emission (SASE) FEL that reached saturation in a non-waveguide operation mode, thus proving the feasibility of such FELs and highlighting their promise of one day achieving laser-like operations well into the x-ray spectrum. This achievement is particularly remarkable because it was accomplished with minimal interruption to APS user-beam operation. The SPIRIT experiment is a recent addition to the FEL system. It was assembled and is being commissioned by a team of scientists. The experiments capitalize heavily on the wavelength tunability over the VUV wavelength range and the high energy delivered per pulse, features not available anywhere else.