Author: Takayama, K.
Paper Title Page
TUPC096 Solid-state Marx Generator Driven Einzel Lens Chopper 1233
 
  • K. Takayama, T. Arai
    KEK, Ibaraki, Japan
  • T. Adachi, K.W. Leo
    Sokendai, Ibaraki, Japan
  • A. Tokuchi
    Pulsed Power Japan Laboratory Ltd., Kusatsu-shi Shiga, Japan
 
  A new type of pulse chopper called an Einzel lens chopper* is described. The Einzel lens, placed immediately after an electron cyclotron resonance ion source, is driven by high-voltage pulses generated by a newly developed solid-state Marx generator. A rectangular negative barrier pulse-voltage is controlled in time. The barrier pulse is switched on only when a beam pulse is required. When the barrier pulse is off, the DC voltage across the Einzel lens reflects ions back upstream with almost zero velocity. The device has been actually used as a chopper for the KEK Digital Accelerator, which is a small-scale induction synchrotron employing no a large injector and capable of providing a wide variety of ions, has been constructed at KEK**. A He ion beam of 50 micro-ampere was chopped in 5 micro-sec with rise/fall time of 40 nsec.
* T.Adachi et al., “A Solid-State Marx Generator Driven Einzel Lens Chopper”, submitted to Appl. Phys. Lett.
** T. Iwashita et al., “KEK Digital Accelerator”, Phys. Rev. ST-AB, published in 2011.
 
 
WEOBA02 KEK Digital Accelerator and its Beam Commissioning 1920
 
  • K. Takayama, T. Arai, Y. Arakida, M. Hasimoto, T. Iwashita, E. Kadokura, T. Kawakubo, T. Kubo, H. Nakanishi, K. Okamura, H. Someya, A. Takagi, M. Wake
    KEK, Ibaraki, Japan
  • T. Adachi, K.W. Leo
    Sokendai, Ibaraki, Japan
  • K. Okazaki
    Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture, Japan
 
  The digital accelerator (DA), which is a small-scale induction synchrotron no requiring a high-energy injector accelerator and capable of providing a wide variety of ions, has been constructed at KEK*. Since the last winter beam commissioning has been carried out. Preliminary results of the beam commissioning experiment as well as the accelerator itself will be presented at the conference. The KEK-DA consists of a 200 kV high voltage terminal, in which an ECRIS is embedded, 15 m long LEBT, electro-static injection kicker, and a 10 Hz rapid cycle synchrotron, which is the recycle use of the former 500 MeV Booster synchrotron. An ion pulse, which is chopped in 5 μs by the newly developed Marx generator driven chopper**, is guided through the LEBT and injected by the electrostatic kicker, which is turned off before the injected ion pulse completes the first turn. Then the ion pulse is captured with a pair of barrier voltages and accelerated with the induction acceleration voltage through a full acceleration period. Beam commissioning has been started with a He1+ ion beam of 50 micro-ampere. Beam commissioning of other ions such as C, N, O, Ne, and Ar will be expected.
* T. Iwashita et al., “KEK Digital Accelerator”, Phys. Rev. ST-AB, published in 2011.
** T.Adachi et al., “A Solid-State Marx Generator Driven Einzel Lens Chopper”, these proceedings.
 
slides icon Slides WEOBA02 [4.268 MB]  
 
WEPS075 Induction Sector Cyclotron for Cluster Ions 2679
 
  • K. Takayama
    KEK, Ibaraki, Japan
  • T. Adachi
    Sokendai, Ibaraki, Japan
  • W. Jiang
    Nagaoka University of Technology, Nagaoka, Niigata, Japan
  • H. Tsutsui
    SHI, Tokyo, Japan
 
  A novel scheme of a sector cyclotron to accelerate extremely heavy cluster ions, called Induction Sector Cyclotron (ISC)*, is described. Its key feature is fast induction acceleration. An ion bunch is accelerated and captured with pulse voltages generated by transformers**. The acceleration and confinement in the longitudinal direction can be independently handled. Since the transformers are energized by the switching power supply, in which turning on/off of the switching gate is maneuvered by gate signals digitally manipulated from the circulating beam signal of an ion bunch, acceleration synchronizing with the revolution of ion beam is always guaranteed. A cluster ion beam such as C-60, which so far there has been no way to repeatedly accelerate, can be accelerated from extremely low energy to high energy. The fundamental concept of ISC is introduced and beam dynamical issues such as a life time of cluster ions under strong guide fields and repeatedly exerted pulse voltages in the existence of residual molecules are addressed. In addition, the present status of R&D works on a race track-shape induction accelerating cell will be presented.
* K.Takayama et al., submitted for publication (2011).
** K.Takayama and R.J.Briggs, Chapter 11 and 12 in Induction Accelerators (Springer, 2010).
 
 
THPO027 Novel Switching Power Supply utilizing SiC-JFET and its Potential for the Digital Accelerator 3400
 
  • K. Okamura, T. Iwashita, K. Takayama, M. Wake
    KEK, Ibaraki, Japan
  • K. Ise
    Tohoku Electric Power Co., Sendai, Japan
  • Y. Osawa
    SUN-A Corporation, Miyoshi-City, Japan
  • K. Takaki
    Iwate university, Morioka, Iwate, Japan
 
  Funding: Japan Science and Technology Agency
New induction synchrotron system using an induction cell has been developed and constructed at KEK*. We refer to the accelerator using the induction acceleration system combined with digitally controlled PWM power supply as "Digital Accelerator". In that system, the switching power supply is one of the key devices which realize digital acceleration. The requirements of the switching power supply are high voltage (2 kV) and high repetition frequency (1 MHz). In the present system, we used series connected MOSFETs as the switching device and obtained successful operation. However, series connection gives large complexity and less reliability. Among the various switching devices, a SiC-JFET is the promising candidates that substitute existing silicon MOSFET because it has ultrafast switching speed and voltage blocking capability**. Therefore, we have started to develop new device in collaboration with device manufacturers. Switching and heat removal performance of the newly developed SiC-JFET and a future plan will be presented at the conference.
* T. Iwashita et al., “KEK Digital Accelerator”, Phys. Rev. ST-AB, published in 2011.
** K. Ise et al., IEEE Trans. Plasma Sci., pp. 730-736 (2011).