Author: Tanaka, Y.
Paper Title Page
WEPC036 Coherent Synchrotron Radiation Source Based on an Isochronous Accumulator Ring with Femtosecond Electron Bunches 2085
 
  • N.Y. Huang
    NTHU, Hsinchu, Taiwan
  • H. Hama, F. Hinode, S. Kashiwagi, M. Kawai, X. Li, F. Miyahara, T. Muto, K. Nanbu, Y. Tanaka
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  • W.K. Lau
    NSRRC, Hsinchu, Taiwan
  
  A com­pact isochronous ac­cu­mu­la­tor ring has been stud­ied as a source of co­her­ent syn­chrotron ra­di­a­tion (CSR) at a wave­length re­gion from THz to GHz. Since the thermion­ic rf gun is sub­stan­tial­ly sta­ble in gen­er­al, we an­tic­i­pate a bunch train of very short elec­tron puls­es can be pro­vid­ed sat­is­fac­to­ri­ly by means of ve­loc­i­ty bunch­ing. Care­ful nu­mer­i­cal sim­u­la­tions show pos­si­bil­i­ty of the bunch length of much less than 100 fs with a bunch charge of 20 pC, which will con­tain suf­fi­cient­ly large form fac­tor for pro­duc­tion of CSR at the wave­lengths longer than ~ 0.1 mm. The co­her­ent THz ra­di­a­tion of high av­er­age power will be achieved if the short bunch­es can be cir­cu­lat­ed in the ac­cu­mu­la­tor ring with­out bunch length­en­ing. This paper will de­scribe the op­ti­miza­tion of thermion­ic in­jec­tor to pro­duce fem­tosec­ond bunch­es in ad­di­tion to study of the lat­tice de­sign­ing of com­plete isochronous op­tics for the ac­cu­mu­la­tor ring.  
 
THPC040 Expected Performance Characteristic of Accelerator-based THz Source at Tohoku University 2990
 
  • H. Hama, F. Hinode, S. Kashiwagi, M. Kawai, X. Li, T. Muto, K. Nanbu, Y. Tanaka
    Tohoku University, School of Science, Sendai, Japan
  • N.Y. Huang
    NTHU, Hsinchu, Taiwan
  
  Funding: This work is supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (S), Contract #20226003.
Sources of co­her­ent syn­chrotron ra­di­a­tion at THz wave­length re­gion have been con­struct­ed at To­hoku Uni­ver­si­ty. Bunch train of ex­treme­ly short­er elec­tron pulse less than 100 fs will be pro­vid­ed by an in­jec­tor linac em­ploy­ing thermion­ic rf gun, where the bunch com­pres­sion will be per­formed by means of ve­loc­i­ty bunch­ing in an ac­cel­er­a­tor struc­ture. Ra­di­a­tion source under de­vel­op­ment are a Hal­bach type pla­nar un­du­la­tor and an ac­cu­mu­la­tor isochronous ring. The un­du­la­tor em­ploys large gap and long pe­ri­od length con­fig­u­ra­tion, so that the res­o­nant fre­quen­cy of 1 THz is achieved when a lower beam en­er­gy of ~ 20 MeV. Since spec­trum of co­her­ent syn­chrotron ra­di­a­tion (CSR) is strong­ly de­pend­ing on lon­gi­tu­di­nal bunch form fac­tor, we have cal­cu­lat­ed CSR spec­tra for var­i­ous con­di­tions of the beam to eval­u­ate the per­for­mance of the THz source. Nu­mer­i­cal sim­u­la­tion with mul­ti-par­ti­cle sys­tem has been car­ried out to un­der­stand the ra­di­a­tion power and an­gu­lar dis­tri­bu­tion as well. The beam trans­port in the un­du­la­tor is cru­cial for qual­i­ty of the ra­di­a­tion be­cause the beam en­er­gy is very much low rel­a­tive to strong fo­cus­ing power. Char­ac­ter­is­tics of THz CSR from the un­du­la­tor will be dis­cussed. 		 
 
THPC041 Injector System of Test Accelerator as Coherent Terahertz Source 2993
 
  • S. Kashiwagi, H. Hama, F. Hinode, M. Kawai, X. Li, T. Muto, K. Nanbu, Y. Tanaka
    Tohoku University, School of Science, Sendai, Japan
  • N.Y. Huang
    NTHU, Hsinchu, Taiwan
  • F. Miyahara
    KEK, Ibaraki, Japan
  
  Funding: This work is supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (S), Contract #20226003.
A test ac­cel­er­a­tor as a co­her­ent ter­a­hertz source (t-ACTS) pro­ject has been under de­vel­op­ment at To­hoku Uni­ver­si­ty, in which a gen­er­a­tion of in­tense co­her­ent ter­a­hertz (THz) ra­di­a­tion from sub-pi­cosec­ond elec­tron bunch will be demon­strat­ed. We will sup­ply a wide-band co­her­ent ra­di­a­tion from bend­ing mag­nets in an isochronous ring and a nar­row-band co­her­ent THz ra­di­a­tion using an un­du­la­tor in a linac. Sta­ble gen­er­a­tion of very short elec­tron bunch is one of the key is­sues in the t-ACTS pro­ject. The in­jec­tor sys­tem is con­sists of a thermion­ic RF gun with two in­de­pen­dent cav­i­ty cells, an alpha mag­net and an ac­cel­er­at­ing struc­ture. A ve­loc­i­ty bunch­ing scheme is em­ployed to pro­duce the very short elec­tron bunch. Com­po­nents of the t-ACTS in­jec­tor ex­cept the ac­cel­er­at­ing struc­ture have al­ready been in­stalled and we have start­ed a high power RF pro­cess­ing of the gun cav­i­ties. The char­ac­ter­is­tics of elec­tron bunch ex­tract­ed from the RF gun are mea­sured by vary­ing phase and am­pli­tude of input RF fields for the gun cav­i­ties. The sta­tus of t-ACTS pro­ject will be pre­sent­ed in the con­fer­ence.