Author: Li, W.W.
Paper Title Page
MOPAB112 A Modified Hybrid 6BA Lattice for the HALF Storage Ring 407
 
  • Z.H. Bai, G.Y. Feng, T.L. He, W. Li, W.W. Li, G. Liu, Z.L. Ren, L. Wang, P.H. Yang, S.C. Zhang, T. Zhang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  
  In this paper, we pro­pose a mod­i­fied hy­brid 6BA lat­tice as the base­line lat­tice of the Hefei Ad­vanced Light Fa­cil­ity (HALF) stor­age ring. Sim­i­lar to the Di­a­mond-II lat­tice, the pro­posed lat­tice cell has one long straight sec­tion and one mid-straight sec­tion; but the two bend units ad­ja­cent to the mid-straight are LGB/RB units (LGB: lon­gi­tu­di­nal gra­di­ent bend, RB: re­verse bend), which can give both lower emit­tance and shorter damp­ing times. The de­signed HALF stor­age ring, with an en­ergy of 2.2 GeV and 20 lat­tice cells, has a nat­ural emit­tance of about 85 pm·rad.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB112  
About • paper received ※ 15 May 2021       paper accepted ※ 20 May 2021       issue date ※ 01 September 2021  
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TUPAB265 Bunch Lengthening of the HALF Storage Ring in the Presence of Passive Harmonic Cavities 2082
 
  • T.L. He, Z.H. Bai, G.Y. Feng, W. Li, W.W. Li, G. Liu, L. Wang, H. Xu, S.C. Zhang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  
  A pas­sive 3rd har­monic RF sys­tem, being nec­es­sary for the Hefei Ad­vanced Light Fa­cil­ity (HALF) stor­age ring under de­sign, will be em­ployed to lengthen the bunches for sup­press­ing the in­tra­beam scat­ter­ing and im­prov­ing the beam life­time. How­ever, the tran­sient beam load­ing due to the fun­da­men­tal mode may sig­nif­i­cantly re­duce the bunch length­en­ing. Since the scale of tran­sient ef­fects is pro­por­tional to R/Q, the ef­fects of R/Q on bunch length­en­ing, in uni­form fill pat­tern with the near-op­ti­mum con­di­tion ful­filled, are an­a­lyzed by multi­bunches mul­ti­par­ti­cles track­ing sim­u­la­tion. It in­di­cates that the pas­sive su­per­con­duct­ing har­monic cav­ity with a lower R/Q is pre­ferred by HALF.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB265  
About • paper received ※ 16 May 2021       paper accepted ※ 18 June 2021       issue date ※ 20 August 2021  
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TUPAB266 Periodic Transient Beam Loading Effects Predicted by a Semi-Analytical Method 2086
 
  • T.L. He, Z.H. Bai, G. Feng, W. Li, W.W. Li, G. Liu, L. Wang, H. Xu, S.C. Zhang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  
  In this paper, we im­prove a semi-an­a­lyt­i­cal method, which can be not only used for bunch length­en­ing under equi­lib­rium con­di­tions, but also ap­plied to the pre­dic­tion of a pe­ri­odic tran­sient beam load­ing ef­fect. This pe­ri­odic tran­sient is in­duced by the pres­ence of the pas­sive har­monic cav­ity and might be en­coun­tered under spe­cific con­di­tions for a ul­tra-low emit­tance stor­age ring with a higher beam cur­rent.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB266  
About • paper received ※ 16 May 2021       paper accepted ※ 21 June 2021       issue date ※ 24 August 2021  
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WEPAB077 High Power Terahertz Cherenkov Free Electron Laser from a Waveguide with a Thin Dielectric Layer by a Near-Relativistic Electron Beam 2769
 
  • W.W. Li, T.L. He, Z.G. He, R. Huang, Q.K. Jia, S.M. Jiang, L. Wang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  
  Funding: National Natural Science Foundation of China (11705198, 11775216, 11805200) Fundamental Research Funds for the Central Universities (No. WK2310000082 and No. WK2310000090)
Cor­ru­gated and di­elec­tric struc­tures have been widely used for pro­duc­ing ac­cel­er­a­tor based ter­a­hertz ra­di­a­tion source. Re­cently, the novel schemes of the sub-ter­a­hertz free elec­tron laser (FEL) from a metal­lic wave­guide with cor­ru­gated walls and a nor­mal di­elec­tric loaded wave­guide dri­ven by a near-rel­a­tivis­tic (beam en­ergy of a few MeV) pi­cosec­ond elec­tron beam were stud­ied re­spec­tively. Such a beam is used for dri­ving res­o­nant modes in the wave­guide, and if the pipe is long enough, the in­ter­ac­tion of these modes with the co-prop­a­gat­ing elec­tron beam will re­sult in mi­cro-bunch­ing and the co­her­ent en­hance­ment of the wake­field ra­di­a­tion. It of­fers a promis­ing can­di­date for com­pact ac­cel­er­a­tor-based high power ter­a­hertz source which can be re­al­ized with rel­a­tively low en­ergy and low peak-cur­rent elec­tron beams. How­ever the choices of the wave­guide above is less ef­fec­tive in order to ob­tain high power with fre­quency around 1THz. In this paper, we pro­pose to use the wave­guide with a thin di­elec­tric layer in­stead, and high power ra­di­a­tion (>~10 MW) around 1 THz is ex­pected to ob­tain in the pro­posed struc­ture ac­cord­ing to the sim­u­la­tion re­sults. 		 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB077  
About • paper received ※ 12 May 2021       paper accepted ※ 23 June 2021       issue date ※ 22 August 2021  
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