Author: Widmann, C.
Paper Title Page
TUPO005 Design Optimization for a Non-Planar Undulator for the JETI-Laser Wakefield Accelerator in Jena 1452
 
  • V. Afonso Rodriguez, T. Baumbach, A. Bernhard, G. Fuchert, A. Keilmann, P. Peiffer, C. Widmann
    KIT, Karlsruhe, Germany
  • M. Kaluza, M. Nicolai
    IOQ, Jena, Germany
  • R. Rossmanith
    Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
  
  In a laser wake­field ac­cel­er­a­tor (LWFA), ex­cit­ed by a fem­tosec­ond laser pulse elec­trons are ac­cel­er­at­ed to sev­er­al 100 MeV with­in a few cen­time­ters. The en­er­gy spread of the elec­tron beam is rel­a­tive­ly large and varies from shot to shot. In order to ob­tain monochro­mat­ic pho­tons in an un­du­la­tor de­spite the en­er­gy spread, the fol­low­ing idea was pro­posed. Two bend­ing mag­nets and a drift space in be­tween pro­duces dis­per­sion so that par­ti­cles with dif­fer­ent en­er­gies have dif­fer­ent trans­verse po­si­tions. The beam en­ters a non-pla­nar un­du­la­tor, e.g. cylin­dri­cal pole ge­om­e­try, where the K-val­ue also varies with trans­verse po­si­tion. If the two vari­a­tions in the trans­verse di­rec­tion (par­ti­cle en­er­gy and K-val­ue) com­pen­sate each other the gen­er­at­ed light is more monochro­mat­ic than with a con­ven­tion­al pla­nar un­du­la­tor. In this paper such a mod­i­fied un­du­la­tor de­sign op­ti­mized for the JETI-LW­FA in Jena is pre­sent­ed. An ex­per­i­ment to test this con­cept is in prepa­ra­tion.  
 
TUPO006 Design of a Dispersive Beam Transport Line for the JETI Laser Wakefield Accelerators 1455
 
  • C. Widmann, V. Afonso Rodriguez, T. Baumbach, A. Bernhard, P. Peiffer
    KIT, Karlsruhe, Germany
  • M. Kaluza, M. Nicolai
    IOQ, Jena, Germany
  • R. Rossmanith
    Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
  
  Laser wakefield ac­cel­er­a­tors (LWFA) emit elec­trons with en­er­gies of a few 100 MeV at very short bunch lengths while hav­ing a com­pact de­sign. How­ev­er, elec­tron bunch­es from LWFA show a larg­er en­er­gy spread than those of con­ven­tion­al ac­cel­er­a­tors. This is a chal­lenge when using these bunch­es e.g. to gen­er­ate ra­di­a­tion in an un­du­la­tor. A pos­si­ble strat­e­gy to cope with that is to spec­tral­ly dis­perse the bunch and match the re­sult­ing spa­tial dis­tri­bu­tion with a spa­tial­ly vary­ing un­du­la­tor field am­pli­tude. For re­al­iz­ing the dis­per­sion a pair of dipole mag­nets is used. The elec­trons leav­ing this dipole chi­cane have to meet cer­tain re­quire­ments im­posed by the un­du­la­tor: In the deflec­tion plane the beam has to be col­li­mat­ed and its en­er­gy dis­tri­bu­tion must match the un­du­la­tor field. In the other transver­sal plane the beam has to be fo­cussed on the cen­ter of the un­du­la­tor keep­ing the value of the beta func­tion small. To in­clude this in the com­pact de­sign of the setup, a com­bi­na­tion of spe­cial­ly de­signed quadrupole and sex­tupole mag­nets is em­ployed. In this con­tri­bu­tion the de­sign of the setup and the re­sults of the par­ti­cle track­ing through this chi­cane are pre­sent­ed.