Development of Fast Output VME Boards with External Clock

E. Takada, N. Araki, A. Itano*, M. Kanazawa, M. Kumada, K. Noda,
S. Sato, E. Hishitani**, and Y. Yamamoto**
National Institute of Radiological Sciences, Chiba 263
*Hyogo Prefecural Government, Kobe 650
**Hitachi Zosen Corporation, Osaka 554, JAPAN


Heavy ion acceleration in a synchrotron requires dynamic control of lattice magnets and the rf system to cover a wide variety of species and energy of ions. For example, spill-by-spill energy change is necessary for three dimensional scanning in cancer radiotherapy. The excitation pattern of lattice magnets must be switched without interruption to beam, while the rf system should follow the frequency shift caused by the change of magnetic field. Since both magnet power supplies and rf system (acceleration voltage, frequency, ferrite bias current, etc.) are driven by digital settings from VME modules, although with a different clock system, in the HIMAC synchrotron as well, development of a new VME module that can deal more dynamically with both magnets and rf in a unified manner is initiated as a logical extension of the present system. Features include: 20 bit(max.) pattern output with 125 kHz response to external bi-directional clock trigger; versatile pattern switching with Look-Up-Table and selection command input, feed-back loop capability through VSB bus, with high performance RISC micro processor. System construction and firmware concept will be discussed also.