The Spallation Neutron Source (SNS) is a facility being designed for scientific and industrial research and development. SNS will generate and use neutrons as a diagnostic tool for medical purposes, material science, etc. The neutrons will be produced by bombarding a heavy metal target with a high-energy beam of protons, generated and accelerated with a linear particle accelerator, or linac. The low energy end of the linac consists of two room temperature copper structures, the drift tube linac (DTL), and the coupled cavity linac (CCL). Both of these accelerating structures use large amounts of electrical energy to accelerate the proton beam. Approximately 60-80% of the electrical energy is dissipated in the copper structure and must be removed. This is done using specifically designed water cooling passages within the linac's copper structure. Cooling water is supplied to these cooling passages by specially designed resonance control and water cooling systems.One of the primary components in the DTL and CCL water cooling systems, is a water purification system that is responsible for minimizing erosion, corrosion, scaling, biological growth, and hardware activation. The water purification system consists of filters, ion exchange resins, carbon beds, an oxygen scavenger, a UV source, and diagnostic instrumentation. This paper reviews related issues associated with water purification and describes the mechanical design of the SNS Linac water purification system.

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The Spallation Neutron Source (SNS) is a major research facility being constructed at Oak Ridge National Laboratory by a collaboration of six national laboratories. The coupled-cavity linac (CCL) is part of the accelerating chain that provides the beam power to the neutron-producing target. As part of the SNS R&D program, the CCL physics and engineering designs were validated with a copper hot model, consisting of two full segments coupled by a radio frequency (RF)-powered bridge coupler. The RF tuning procedures worked as expected. The hot model operated up to 480-kW peak power at a full 7.2% RF duty factor with an accelerating field of 4.08 MV/m. The peak and average powers were 17% higher than maximum design values. Measured cavity field flatness, field stability, Q, iris coupling, and stop band agreed closely with calculated performance. In addition to validating manufacturing, assembly, and handling procedures, the CCL hot model successfully tested the temperature and resonanttracking control, amplitude and frequency algorithms, hardware and personnelprotect interlocks, vacuum conditioning procedure and time, vacuum-system performance (pressure, contaminants), and dark-current x-ray levels.