Mechanical Design Concepts of Dynamitron Accelerators

On the basis of ready availability and reasonable cost, methyl methacrylate (lucite or plexiglass) has proven to be suitable for use as the structural material in the high voltage columns of Dynamitron accelerators. This material has reasonably high tensile strength, good machining characteristics, ready availability at reasonable cost, and good electrical properties such as high dielectric strength, high resistivity and resistance to surface tracking. The structures made of Acrylic material conform to standard forms of beam analysis provided deflections are kept within reason and stress within recommended limits. A 4.0 Mev column 15 feet long by 42 inches in diameter, supporting at a total weight of 1500 pounds is now in operation. The cinch rod method of supporting beam tubes has proven to be practical and allows several side benefits, such as easy handling, allowing for short sections of the tube to be replaced if damaged, ease of insertion of apertures if and when required, and assembly of modular sections to any given length desired. A new method, a combination of cinch rods and counter weights, has proven a satisfactory improvement that still has these desirable features without requiring unreasonable cinch rod tension. A 4.0 Mev tube 12 feet long, weighing 480 pounds and carrying an ion source, lens and getter-pump assembly weighing 55 pounds at the high voltage end is now in operation.