USE OF MACROSCOPIC SOLID STRUCTURE IN ACCELERATORS

A pre-aimed nozzle device comprises a nozzle block with an orifice wafer attached thereto. The nozzle block has an aiming surface. The orifice wafer comprises an annular orifice element retained in the body of the wafer in a manner whereby the orifice element and wafer are bonded to the nozzle block with the opening of the orifice element perpendicular to the aiming surface. The orifice wafer is made by encapsulating a straight section of glass tubing in a block of ceramic. The block is machined with precision external location surfaces. A groove is machined into the block with internal location surfaces parallel with the external location surfaces. After potting of the tube in the groove with solder glass, the wafer block is cut along planes perpendicular to the external location surfaces to obtain annular orifice elements precisely aimed relative to the wafer body.