Author: Fujita, T.F.
Paper Title Page
TUXO03 Two-frequency Heating Technique for Stable ECR Plasma 10
 
  • A. Kitagawa, M. Muramatsu
    NIRS, Chiba-shi, Japan
  • S. Biri, R. Rácz
    ATOMKI, Debrecen, Hungary
  • T.F. Fujita
    National Institute of Radiological Sciences, Chiba, Japan
  • Y. Kato
    Osaka University, Graduate School of Engineering, Osaka, Japan
  • N. Sasaki, W. Takasugi
    AEC, Chiba, Japan
 
  As a method to improve highly charged ion production, a technique to feed multiple microwaves with different frequencies is well-known. However the reason is not made sufficiently clear. Our group studied with two frequencies close together with a power of 600 W over by 18 GHz NIRS-HEC ECR ion source installed in the Heavy Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences (NIRS). As a result, it was revealed that the improvement of output beam current depends on the total power. In this case it seems that the two-frequency heating technique carries the advantage that the plasma instability at high microwave power is relieved. The effectiveness of an additional microwave depends on its frequency. It is necessary to optimize an additional frequency precisely; several tens MHz step against 18 GHz. The optimized frequency is directly influenced by the magnetic configuration. The necessary requirements for an additional microwave and the procedure of optimization in order to obtain a large advantage will be discussed.  
slides icon Slides TUXO03 [1.590 MB]  
 
TUPP04 Design of a Compact ECR Ion Source for Various Ion Production 49
 
  • M. Muramatsu, S. Hojo, Y. Iwata, K. Katagiri, A. Kitagawa, Y. Sakamoto, S. Sato
    NIRS, Chiba-shi, Japan
  • A.G. Drentje
    KVI, Groningen, The Netherlands
  • T.F. Fujita
    National Institute of Radiological Sciences, Chiba, Japan
 
  Compact ECR ion source with all permanent magnets, so called Kei2, was developed for high energy carbon ion therapy facility at National Institute of Radiological Sciences. Kei2 source was design for production of only carbon ion for medical treatment. A copy of Kei2, so called KeiGM is used for Gunma University. Kei series are optimized for carbon ion production. In order to produce various ion beams for research, we design a new compact ECR ion source, so called Kei3. Kei3 is designed based on previous Kei series. In addition, there are three important points: 1) Movable beam extraction system for various extraction current densities, 2) An evaporator and MIVOC method for production of ions from solid materials and metal, and 3) Biased disk method and double frequency heating method for heavier ions. Same permanent magnets and microwave system will be used for easy maintenance and the cost effectiveness. Design of the Kei3 source will be described in this paper.  
 
FRYA02 Status of ECR Ion Sources for Carbon-ion Radiotherapy in Japan 200
 
  • A. Kitagawa, M. Muramatsu
    NIRS, Chiba-shi, Japan
  • A.G. Drentje
    KVI, Groningen, The Netherlands
  • T.F. Fujita
    National Institute of Radiological Sciences, Chiba, Japan
  • M. Kanazawa
    SAGA HIMAT, Saga, Japan
  • N. Sasaki, W. Takasugi
    AEC, Chiba, Japan
  • E. Takeshita, S. Yamada
    Gunma University, Heavy-Ion Medical Research Center, Maebashi-Gunma, Japan
 
  Heavy-ion radiotherapy is successfully carried out at the Heavy Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences (NIRS) since 1994. Now three facilities are in operation and two are under construction in Japan. Over 8000 cancer patients have already been treated. 140-400 MeV/u carbon beams were selected for the first clinical trials at HIMAC because carbon is one of the best candidates which gives good localized biological dose distribution for the typical conditions, a depth of 10 - 25 cm and a thickness of several cm. Based on the clinical results, all the patients have been treated by carbon beams at present. The ion source needs to realize a stable carbon beam with the same conditions for daily operation. Since operators are usually not specialists of the ion source, the source should not require complicated manual tuning. In addition, shorter maintenance time and cycle are better for a hospital. ECR ion sources are utilized for such requirements in each facility. We report the recent status of the ECR ion sources at heavy-ion radiotherapy facilities in Japan.  
slides icon Slides FRYA02 [5.652 MB]