Disk and washer linac and method of manufacture

A bridge coupler for use in a coupled-cavity linear accelerator, said bridge coupler comprising:

• a generally cylindrical coupler outer wall having a first end and a second end;
• a pair of axially spaced disks with one disk disposed adjacent to each end of said coupler wall;
• an inner hub having a central aperture defining a charged particle beam acceleration path within said bridge coupler, said hub having a structure defining a cavity adjacent to said central window for containing equipment such as focusing means for shaping and/or directing a beam of charged particles;
• and
• an annular rim integral with said inner hub, said rim disposed outwardly of said inner hub, said rim supported by said coupler outer wall, said rim possessing an annular structure which stratifies the electromagnetic fields within said bridge coupler walls such that RF power may be efficiently coupled into said bridge coupler structure.

A method for fabricating a tank used in a coupled-cavity linear accelerator, said tank including:

• a generally cylindrical outer wall;
• a plurality of disks having an outside diameter greater than the inside diameter of said tank wall;
• and
• a plurality of washers for mounting on predetermined ones of said disks, said method comprising the following steps:
• (a) assembling outside of said tank wall at least one washer on one of said disks to form an assembly;
• (b) effecting a relative temperature differential between said assembly and said tank wall so that said assembly can be received inside said tank wall without deformation;
• (c) locating said assembly at a predetermined location inside said tank wall;
• and
• (d) permitting the relative temperatures of said assembly and said tank wall to move toward equilibrium, whereby the inner surface of said tank wall is indented by the disk of said assembly to hold said assembly inside said outer wall.