Author: Orlandi, G.L.
Paper Title Page
MOBL1 Instrumentation and Results from the SwissFEL Injector Test Facility 12
 
  • R. Ischebeck, V.R. Arsov, S. Bettoni, B. Beutner, M.M. Dehler, A. Falone, F. Frei, I. Gorgisyan, Ye. Ivanisenko, P.N. Juranic, B. Keil, F. Löhl, G.L. Orlandi, M. Pedrozzi, P. Pollet, E. Prat, T. Schietinger, V. Schlott, B. Smit
    PSI, Villigen PSI, Switzerland
  • P. Peier
    DESY, Hamburg, Germany
  
  The Swiss­FEL In­jec­tor Test Fa­cil­ity (SITF) has been equipped with nu­mer­ous pro­to­type di­ag­nos­tics (BPMs, screen mon­i­tors, wire scan­ners, op­ti­cal syn­chro­tron ra­di­a­tion mon­i­tor, com­pres­sion (THz) mon­i­tor, bunch ar­rival time mon­i­tor, EO spec­tral de­cod­ing mon­i­tor, charge and loss mon­i­tor) specif­i­cally de­signed for the low charge Swiss­FEL op­er­a­tion modes. The de­sign of the di­ag­nos­tics sys­tems and re­cent mea­sure­ment re­sults will be pre­sented.  
slides icon Slides MOBL1 [35.165 MB]  
 
TUPC40 Bunch Length Measurements Using Correlation Theory in Incoherent Optical Transition Radiation 471
 
  • B. Smit, F. Frei, R. Ischebeck, G.L. Orlandi, V. Schlott
    PSI, Villigen PSI, Switzerland
  
  Funding: Paul Scherrer Institut (PSI)
As Free Elec­tron Lasers cre­ate ul­tra-short bunch lengths, the lon­gi­tu­di­nal di­ag­nos­tic for such femto-sec­ond bunches be­comes more dif­fi­cult. We sug­gest a bunch length method using the spec­tral analy­sis of in­co­her­ent Op­ti­cal Tran­si­tion Ra­di­a­tion (OTR) in the vis­i­ble fre­quency do­main. The fre­quency re­sponse of OTR is taken by in­sert­ing an alu­minium coated sil­i­con wafer into the elec­tron beam. The OTR light is col­lected with mir­ror op­tics into an op­ti­cal fibre, which is cou­pled to a spec­trom­e­ter (334 THz to 1500 THz). The res­o­lu­tion of the spec­trom­e­ter al­lows us to mea­sure bunch length lower than 100 fs rms. Bunch length was var­ied from 100 femto-sec­onds down to a few femto-sec­onds. The spec­tral re­sponse of Op­ti­cal Tran­si­tion Ra­di­a­tion (OTR) showed an in­crease of the cor­re­la­tion be­tween neigh­bour­ing fre­quen­cies as bunch length was re­duced. 		 
 
TUPF07 Covariance and Temporal Causality in the Transition Radiation Emission by an Electron Bunch 511
 
  • G.L. Orlandi
    PSI, Villigen PSI, Switzerland
  
  A model of the tran­si­tion ra­di­a­tion emis­sion by a N elec­tron bunch must con­form to co­vari­ance and causal­ity. The co­vari­ance of the charge den­sity must im­print the tran­si­tion ra­di­a­tion en­ergy spec­trum via a proper for­mu­la­tion of the charge form fac­tor. The emis­sion phases of the ra­di­a­tion pulse must be causal­ity cor­re­lated with the tem­po­ral se­quence of the N elec­tron col­li­sions onto the metal­lic screen. Co­vari­ance and tem­po­ral causal­ity are the two faces of the same coin: fail­ing in im­ple­ment­ing one of the two con­straints into the model nec­es­sar­ily im­plies be­tray­ing the other one. The main for­mal as­pects of a co­vari­ance and tem­po­ral-causal­ity con­sis­tent for­mu­la­tion of the tran­si­tion ra­di­a­tion en­ergy spec­trum by an N elec­tron beam are here de­scribed. In the case of a tran­si­tion ra­di­a­tor with a round sur­face, ex­plicit for­mal re­sults are pre­sented.  
 
TUPF08 Characterization of Compressed Bunches in the SwissFEL Injector Test Facility 515
 
  • G.L. Orlandi, M. Aiba, F. Baerenbold, S. Bettoni, B. Beutner, H. Brands, P. Craievich, F. Frei, R. Ischebeck, E. Prat, T. Schietinger, V. Schlott
    PSI, Villigen PSI, Switzerland
  
  The qual­ity of the beam trans­verse emit­tance at the cath­ode and the uni­for­mity of the lon­gi­tu­di­nal com­pres­sion of the elec­tron bunch are es­sen­tial for the las­ing ef­fi­ciency of a Free Elec­tron Laser. In Swiss­FEL the lon­gi­tu­di­nal com­pres­sion of the elec­tron beam is per­formed by means of two mag­netic chi­canes and an off-crest ac­cel­er­a­tion scheme. The cur­va­ture in­duced on the beam lon­gi­tu­di­nal phase-space dur­ing the com­pres­sion can be com­pen­sated by means of an X-band cav­ity. The beam lon­gi­tu­di­nal phase-space can be ex­per­i­men­tally char­ac­ter­ized by means of a Trans­verse De­flect­ing Cav­ity (TDC) and a pro­file mon­i­tor in a dis­per­sive sec­tion. Lon­gi­tu­di­nal phase-space mea­sure­ments at the Swiss­FEL In­jec­tor Test Fa­cil­ity under com­pres­sion with and with­out X-band lin­earizer are pre­sented. In ad­di­tion, en­ergy spread mea­sure­ments done by mon­i­tor­ing the Syn­chro­tron Ra­di­a­tion (SR) emit­ted by the elec­tron beam in the dis­per­sive sec­tion of the chi­cane are shown. A com­par­i­son with nu­mer­i­cal sim­u­la­tions is pre­sented.  
 
WEPC36 Development of Electron Bunch Compression Monitors for SwissFEL 769
 
  • F. Frei, B. Beutner, I. Gorgisyan, R. Ischebeck, G.L. Orlandi, P. Peier, E. Prat, V. Schlott, B. Smit
    PSI, Villigen PSI, Switzerland
  • P. Peier
    DESY, Hamburg, Germany
  
  Swiss­FEL will be a hard x-ray fourth gen­er­a­tion light source to be built at Paul Scher­rer In­sti­tut (PSI), Switzer­land. In Swiss­FEL the elec­tron bunches will be pro­duced with a length of 3ps and will then be com­pressed by a fac­tor of more than 1000 down to a few fs in order to gen­er­ate ultra short x-ray pulses. There­fore re­li­able, ac­cu­rate and non­in­va­sive lon­gi­tu­di­nal di­ag­nos­tic is es­sen­tial after each com­press­ing stage. In order to meet the re­quire­ments of this ma­chine, new mon­i­tors have to be de­vel­oped. We will pre­sent re­cent re­sults of se­tups that mea­sure elec­tro-mag­netic ra­di­a­tion, namely edge, syn­chro­tron and dif­frac­tion ra­di­a­tion, emit­ted by the elec­tron bunches (far field, spec­tral do­main). These mon­i­tors are tested in the Swiss­FEL In­jec­tor Test Fa­cil­ity. A state of the art S-band Trans­verse De­flect­ing Cav­ity to­gether with a Screen Mon­i­tor is used for cal­i­bra­tion.