Navy Funds Research to Mitigate Coolant Channel Corrosion and Gun Arcing

The U.S. Navy funded the Phase I Option of CCR’s program to use innovative coatings to suppress arcing in electron guns and reduce or eliminate corrosion in RF systems deployed in the fleet. The corrosion occurs in copper coolant channels in RF sources and solenoids due to excess oxygen and salts in the coolant.

TWT collector setup for application of protective coolant channel coating
Figure 1. TWT collector setup for application of protective coolant channel coating

CCR is developing coatings to prevent coolant channel corrosion in collaboration with N.C. State University. This follows highly successful life test studies that demonstrated coolant channel lifetime could be increased more than 500% using a nanometer-scale coating of ceramic. The coating is applied by flowing a sequence of gases through the device’s cooling system. Figure 1 shows the setup to coat a TWT collector. It is anticipated the coating will be added prior to final device tests. The process would be applicable to any fluid cooled device where high quality coolant is not available.

The arcing issue arises in klystrons following weeks or months of stand-by operation. The sudden application of high voltage creates spurious electron emission from the focus electrode, immediately taking the system off-line.During the next few months, CCR and N.C. State University will test the process on the cooling circuit of a solenoid manufactured by Arnold Magnetic Technologies.

High Voltage Cathode Test Facility
Figure 2. High Voltage Cathode Test Facility

CCR is investigating coatings that preferentially react with oxygen. This program will determine if coatings of carbon, titanium carbide or tantalum carbide will absorb the oxygen and prevent barium oxide formation. High voltage tests are planned during the next few months using CCR’s cathode test chamber (Figure 2).

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