05aE52P
核融合駆動用加速器のコンパクト化に関する設計研究	 	 Fundamental design of compact high-energy hadron accelerator
for nuclear fusion driver
佐野光1、浅井朋彦1、小口治久2、中村英滋3-5,1,8、酒井泉5、石禎浩6、上杉智教6、高山正和7、
薮上信8、稲垣滋9	 
日大1、産総研2、ＫＥＫ加速器3、総研大4、福井大5、京大原子炉実験所6、秋田県立大7、	 東北学院大8、九大応力研9	 	 
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Hikaru	 Sano ,	 Tomohiko	 Asai ,	 Haruhisa	 Koguchi2,	 Eiji	 Nakamura3-5,	 1,	 8,	 Izumi	 Sakai5,	 
Sadahiro	 Ishi6,	 Tomonori	 Uesugi6,	 Masakazu	 Takayama7,	 Shin	 Yabukami8,	 Shigeru	 Inagaki9	 
Nihon	 Univ.1,	 AIST2,	 KEK	 Acc.-Lab.3,	 SOKENDAI4,	 Fukui	 Univ.5,	 KURRI6,	 Akita	 Pref.	 Univ.7,	 
Tohoku	 Gakuin	 Univ.8,	 RIAM9	 	 	 The	  application	  of	  GeV-class	  hadron	 particles	 to	 new	 energy	 production	 by	 using	 
nuclear	 fusion	 reactors	 has	 been	 discussed.	 
The	  engineering	  techniques	  to	  produce	 high-energy	  particles	  have	  been	  rapidly	 developed	 recently,	 and	 the	 techniques	 are	 also	 used	 to	 the	 NBI	 (Neutral	 Beam	 Injection)	 
for	 plasma	 science	 research	 and	 a	 new	 study	 of	 muon-catalyzed	 fusion.	 On	 the	 other	 hand,	 the	  electric	  power	  conversion	  ratio	  of	 conventional	 particle	 accelerators	 is	 very	 low.	  LINAC	  has	  better	  electric	  power	 
conversion	 characteristics	 and	 is	 capable	 to	 apply	  the	  resonant	  cavities	  with	 
high-gradient	 electric	 field	 of	 35	 MV/m	 [1],	 
but	 the	 scale	 of	 LINAC	 is	 large.	 Cyclotron	 is	  the	  most	  popular	  accelerator	  and	  is	 compact,	 but	 the	 large	 amount	 of	 magnetic	 
materials	 of	 ten	 thousand	 tons	 is	 required	 to	 produce	 GeV-class	 particles.	 Synchrotron	 is	 compact	 and	 does	 not	 require	 such	 huge	 magnetic	  materials,	  but	  the	  output	  beam	 power	 is	 low	 and	 it	 is	 subtle	 unstable	 for	 
AC-magnetic	  field	  operation	  to	  supply	 
high-energy	 beam.	 The	 FFAG	 accelerator	 [2]	 
is	 attractive	 for	 this	 study	 because	 it	 is	 compact	 with	 small	 magnetic	 materials,	 and	 is	  capable	  to	  supply	  stable	  beam	  for	 
DC-magnetic	  field	  operation,	  although	  the	 electric	  field	  of	  the	  acceleration	 
rf-devices	 is	 low	 up	 to	 100	 kV/m	 due	 to	 the	 requirements	  for	  large	  aperture	  and	  for	 
time-variation	 of	 rf	 frequency	 to	 adjust	 to	 the	  non-linear	  velocity	  of	  high-energy	 

particles.	 We	 have	 studied	 to	 improve	 the	 FFAG	 accelerator	 by	 applying	 magnetic	 field	 configuration	 to	 main	 bending	 magnets,	 to	 satisfy	  isochronous	  condition	  and	  phase	 
stability.	  Figure	  1	  shows	  the	  conceptual	 design	 of	 the	 new	 accelerator,	 which	 is	 like	 
microtron	 [3].	 An	 example	 of	 the	 magnetic	 
field	 configuration	 (Fig.	 2)	 and	 the	 related	 
articles	 are	 reported	 here.	 	 

Fig. 1. Conceptual figure of high-energy microtron.

Fig. 2. An example of magnetic field configuration to energize 0.1 GeV
proton up to 1.1 GeV. Left: magnetic field configuration to satisfy theisochronous condition. Right: magnetic field configuration to satisfy
the isochronous condition with phase stability for dp/p = 0.01%.
Acknowledgement: This work was supported by KAKENHI25286089.
References: [1] ILC Reference Design Report, <http://www.linearcollider.org/ILC/Publications/Reference-Design-Report>. [2] Y. Mori, Nucl.
Instr. and Meth. A 451, 300 (2000). [3] D. Hasegawa, et al., Proc. of
the 8th Annual Meeting of PASJ, Aug. 1-3, 2011, Tsukuba, Japan(2011) pp.872.