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Tecapeek, made with Victrex Peek polymer, is intended to improve the cooling jacket for the chamber that produces ions for the Oak Ridge National Laboratory’s (ORNL’s) Spallation Neutron Source (SNS).

The new accelerator-based SNS is a facility that provides intense pulsed neutron beams for scientific research and industrial development.

When the ORNL sought to improve the cooling jacket for the aluminium nitride plasma chamber, it chose Ensinger-extruded Tecapeek made with Victrex Peek polymer in place of polycarbonate because of the material’s dimensional stability under pressure, its low radio-frequency (RF) losses and its ability to be precisely machined, resulting in a one-part design solution.

The plasma chamber containing the RF-driven multi-cusp ion source measures approximately 76mm (3in) in diameter and 178mm (7in) in length.

The ions produced are formed into a pulsed beam and accelerated to very high temperatures.

Dr Robert Welton for the SNS said: ‘The plasma puts a nominal 3kW heat load on the plasma chamber, which must be cooled.

‘The function of the cooling jacket is to cool the plasma chamber by channelling water around it,’ he added.

The original cooling jacket was a two-part design made with a polycarbonate material.

It failed because of cracking and poor tolerances; the application was exceeding what the material could handle.

Another contributing factor was that the high amount of machining that went into creating the two parts added a tremendous amount of internal stress.

Ensinger, in consultation with its distributor AIN Plastics, a division of Thyssenkrupp, offered the ORNL a one-part design solution using Victrex Peek polymer for the cooling jacket.

Timothy Mercurio, south-east sales and marketing manager for AIN, said: ‘They [the ORNL] couldn’t believe it could be done, given the overall complexity of the parts to be combined.

‘But we knew we had the right material with Victrex Peek polymer and the right company to do the machining in American Industrial Plastics [AIP] of Daytona Beach, Florida.

‘Because of AIP’s machining capabilities, we were able to create a worry-free, one-part cooling jacket using Victrex Peek polymer.

‘AIP precision machined the newly designed cooling jacket that carried tolerances of +/-001,’ he added.

Given the critical nature of the application, Victrex Peek polymer offered a number of essential properties, including low thermal conductivity to prevent the ions from reaching high temperatures; radiation resistance because X-rays are present; chemical resistance to prevent reduction by hydrogen; and electrical properties because of low RF losses.

For many research problems, having neutrons available in a series of pulses is better than having a continuous neutron source.

SNS produces pulses that contain neutron intensities 20-100 times higher than that obtainable from the best continuous sources.

Welton continued: ‘Just as we prefer a bright light to a dim one to read the fine print in a book, SNS gives researchers more detailed snapshots of even the smallest samples of physical and biological materials.

‘Most people don’t know it, but neutron-scattering research has a lot to do with our everyday lives.

‘For example, things such as medicine, food, electronics and cars and aeroplanes have all been improved by neutron-scattering research,’ he added.

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