IUCF, Bloomington, Indiana
ORNL, Oak Ridge, Tennessee
SLAC, Menlo Park, California
Recently, discrepancies between model-based and observed linear optics, such as the tune and the closed orbit, have been observed in the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. Accurate accelerator modeling is very important for machine control during the ongoing power ramp up. The Orbit Response Matrix (ORM) method is applied here to find and correct errors in the linear optics of the SNS ring. With the closed orbit data (4472 data points), we are able to calibrate the strength of the steering magnets, the BPM gain factors, and 6 quadrupole power supplies. Current results and remaining challenges will be presented and discussed.
ORNL, Oak Ridge, Tennessee
The 248 meter Spallation Neutron Source accumulator ring is designed to operate with a beam intensity of 1.5·1014 ppp. A major concern for high intensity operation is the possibility of beam instabilities. Recently a series of experiments have been performed to systematically map out the instability parameter space. Beam instabilities have been measured versus betatron tune, ring RF voltage, lattice chromaticity, and beam intensity. The results of these studies are presented here
ORNL, Oak Ridge, Tennessee
Operating at 0.5 MW beam power on target, the Spallation Neutron Source (SNS) is already the world's most powerful pulsed neutron source. However, we are only one third of the way to full power. As we ramp toward full power, the control of the beam and beam loss in the ring will be critical. In addition to practical considerations, such as choice of operating point, painting scheme, and rf bunching, it may be necessary to understand and mitigate collective effects due to space charge, impedances, and electron clouds. In dedicated high intensity beam study shifts, we have already observed resistive wall, impedance driven, and electron cloud activity. The analysis and simulation of this data are important ongoing activities at SNS. This talk will discuss the status of this work, as well as other considerations necessary to the successful full power operation of SNS.
ORNL, Oak Ridge, Tennessee
Charged-particle beam diagnostic devices such as wire scanners and wire harps provide data sets describing the one-dimensional density distributions at a particular location; these data are commonly called profile data. We use these data for further computations, usually beam properties such as position and size. Typically these data require subjective, human, processing to extract meaningful results; this is inefficient and labor intensive. Our ultimate goal is to automate these computations, at least streamline the process. If we hope to implement any type of automation we must make real world considerations. Specifically, we consider information content, noise in the data, and sampling theory. Within this framework we create a general model for the data sets. Using signal processing techniques we identify the minimal sampling requirements for maintaining information content. Using Bayesian analysis we identify the most probable Gaussian signal within the data. We present the major obstacles currently faced concerning robust automation techniques.
BNL, Upton, Long Island, New York
ORNL, Oak Ridge, Tennessee
The charge to this working group was the following:
- Summarize the state of the art in H- charge-exchange injection.
- Summarize recent developments and future possibilities for novel injection techniques.
- Summarize the problems encountered, the needs for further development and improvements in injection and extraction of high-intensity beams.
- Summarize the state-of-the art in collimation system design.
- Summarize the status of benchmarking of collimation system efficiency and performance.