Alternating Gradient Synchrotron Booster Research Articles

Summary of quick disconnect vacuum flanges

In accelerator environments, especially proton machines, high background radiation necessitates the need for quick disconnect vacuum flanges. The use of quick disconnect vacuum flanges significantly reduces the dose of radiation received by workers when installing or removing vacuum chambers in the accelerator. Over the course of many years there have been many designs used for these flanges at Brookhaven National Laboratory for such machines as the Alternating Gradient Synchrotron (AGS), the AGS Booster, and the Relativistic Heavy Ion Collider. Several different flanges with apertures as large as 14 in. in diameter were also evaluated for use in the Spallation Neutron Source project. A summary of various quick connect flanges as well as some commercially available flanges and the evaluation results are presented.

Neutralization of space charge forces using ionized background gas

The Tandem Van de Graaff at Brookhaven National Laboratory has delivered pulsed gold beam to the Alternating Gradient Synchrotron (AGS) and AGS Booster since 1992 for relativistic heavy ion physics. There is an ongoing effort to improve the quality and intensity of the negative ion beam delivered to the Tandem from the present Cs sputter sources. Because the beam energy is low (approximately 30 keV) and the current high, there are significant losses due to space charge forces. One of the ways being explored to overcome these losses is to neutralize the space charge forces with ionized background gas. On an ion source test bench, using three different gases (Ar, N2, and Xe), the percentage of current transported from the source to a downstream Faraday cup was increased from 10% to 40% by bleeding in gas. Bleeding in Xe resulted in the best transmission. The time dependence of the neutralization as a function of gas pressure was also observed. This system is presently being transferred to the Negative Ion Injector of the Tandem for use in upcoming heavy ion experiments.