Author: Roensch-Schulenburg, J.     [Rönsch-Schulenburg, J.]
Paper Title Page
MOP059 Beam Dynamic Simulations for Single Spike Radiation with Short-Pulse Injector Laser at FLASH 173
 
  • M. Rehders
    University of Hamburg, Hamburg, Germany
  • J. Rönsch-Schulenburg
    CFEL, Hamburg, Germany
  • J. Rönsch-Schulenburg, J. Roßbach
    Uni HH, Hamburg, Germany
  • S. Schreiber
    DESY, Hamburg, Germany
 
  Funding: The project has been supported by the Federal Ministry of Education and Research of Germany (BMBF) under contract No. 05K10GU2 and FSP301
This paper dis­cusses the gen­er­a­tion of sin­gle spike SASE pulses at soft x-ray wave­length at the free-elec­tron laser FLASH by using very short elec­tron bunches of only a few mi­crom­e­ter bunch length. In order to achieve these ex­tremely short bunch lengths, very low bunch charges (in the order of 20 pC) and short elec­tron bunches ex­it­ing the photo-in­jec­tor are re­quired. For this, a new short-pulse in­jec­tor laser with ad­justable rms pulse du­ra­tion in the range of 0.7 ps to 1.6 ps and bunch charges up to 200 pC was in­stalled, ex­tend­ing the elec­tron beam pa­ra­me­ter range be­fore bunch com­pres­sion in mag­netic chi­canes. Beam dy­namic stud­ies have been per­formed to op­ti­mize the in­jec­tion and com­pres­sion of low-charge elec­tron bunches by con­trol­ling the ef­fect of co­her­ent syn­chro­tron ra­di­a­tion and space-charge in­duced bunch length­en­ing and emit­tance growth. Op­ti­miza­tion in­cludes the pulse pa­ra­me­ters of the in­jec­tor laser. The sim­u­la­tion codes ASTRA, CSR­track and Gen­e­sis 1.3 were em­ployed.
 
 
MOP060 Demonstration of SASE Suppression Through a Seeded Microbunching Instability 177
 
  • C. Lechner, A. Azima, M. Drescher, L.L. Lazzarino, Th. Maltezopoulos, V. Miltchev, T. Plath, J. Rönsch-Schulenburg, J. Roßbach
    Uni HH, Hamburg, Germany
  • S. Ackermann, J. Bödewadt, G. Brenner, M. Dohlus, N. Ekanayake, T. Golz, E. Hass, K. Honkavaara, T. Laarmann, T. Limberg, E. Schneidmiller, N. Stojanovic, M.V. Yurkov
    DESY, Hamburg, Germany
  • K.E. Hacker, S. Khan, R. Molo
    DELTA, Dortmund, Germany
 
  Funding: Supported by Federal Ministry of Education and Research of Germany under contract No. 05K10PE1, 05K10PE3, 05K13GU4, and 05K13PE3 and the German Research Foundation programme graduate school 1355.
Col­lec­tive ef­fects and in­sta­bil­i­ties due to lon­gi­tu­di­nal space charge and co­her­ent syn­chro­tron ra­di­a­tion can de­grade the qual­ity of the ul­tra-rel­a­tivis­tic, high-bril­liance elec­tron bunches needed for the op­er­a­tion of free-elec­tron lasers. In this con­tri­bu­tion, we demon­strate the ap­pli­ca­tion of a laser-in­duced mi­crobunch­ing in­sta­bil­ity to se­lec­tively sup­press the SASE process. A sig­nif­i­cant de­crease of pho­ton pulse en­er­gies was ob­served at the free-elec­tron laser FLASH in co­in­ci­dence with over­lap of 800 nm laser pulses and elec­tron bunches within a mod­u­la­tor lo­cated ap­prox­i­mately 40 me­ters up­stream of the un­du­la­tors. We dis­cuss the un­der­ly­ing mech­a­nisms based on lon­gi­tu­di­nal space charge am­pli­fi­ca­tion [E.A. Schnei­d­miller and M.V. Yurkov, Phys. Rev. ST Accel. Beams 13, 110701 (2010)] and pre­sent mea­sure­ments.
 
 
TUB04 Operation of FLASH with Short SASE-FEL Radiation Pulses 342
 
  • J. Rönsch-Schulenburg, E. Hass, N.M. Lockmann, T. Plath, M. Rehders, J. Roßbach
    Uni HH, Hamburg, Germany
  • G. Brenner, S. Dziarzhytski, T. Golz, H. Schlarb, B. Schmidt, E. Schneidmiller, S. Schreiber, B. Steffen, N. Stojanovic, S. Wunderlich, M.V. Yurkov
    DESY, Hamburg, Germany
 
  Funding: The project has been supported by the Federal Ministry of Education and Research of Germany (BMBF) under contract No. 05K10GU2 and FSP301
This paper de­scribes the ex­per­i­men­tal ac­tiv­ity on the gen­er­a­tion of very short FEL pulses in the soft x-ray range in the SASE-mode at the high-gain free-elec­tron laser FLASH [1, 2]. The key el­e­ment, a photo-in­jec­tor laser which is able to gen­er­ate laser pulses of about 2 ps FWHM has been op­ti­mized and com­mis­sioned. It al­lows the gen­er­a­tion of shorter bunches with low bunch charge (of up to 200 pC) di­rectly at the photo-cath­ode. Ini­tially shorter in­jec­tor laser pulses and thus shorter bunches eases the re­quired bunch com­pres­sion fac­tor for short pulses below 10 fs du­ra­tion which makes op­er­a­tion of the elec­tron beam for­ma­tion sys­tem to be more ro­bust with re­spect to jit­ters and col­lec­tive ef­fects. As a re­sult, over­all sta­bil­ity of SASE FEL per­for­mance is im­proved. In the op­ti­mal case sin­gle-spike op­er­a­tion can be achieved. In this paper the ex­per­i­men­tal re­sults on pro­duc­tion of short elec­tron bunches and the SASE per­for­mance using the new in­jec­tor laser will be shown and the mea­sured elec­tron bunch and FEL ra­di­a­tion prop­er­ties are dis­cussed. In ad­di­tion, op­ti­miza­tions of bunch di­ag­nos­tics for low charge and short bunches are dis­cussed.
 
slides icon Slides TUB04 [1.201 MB]  
 
THP076 Measurements of the Timing Stability at the FLASH1 Seeding Experiment 913
 
  • C. Lechner, A. Azima, M. Drescher, L.L. Lazzarino, Th. Maltezopoulos, V. Miltchev, T. Plath, J. Rönsch-Schulenburg, J. Roßbach, M. Wieland
    Uni HH, Hamburg, Germany
  • S. Ackermann, J. Bödewadt, H. Dachraoui, N. Ekanayake, B. Faatz, M. Felber, K. Honkavaara, T. Laarmann, J.M. Mueller, H. Schlarb, S. Schreiber, S. Schulz
    DESY, Hamburg, Germany
  • G. Angelova Hamberg
    Uppsala University, Uppsala, Sweden
  • K.E. Hacker, S. Khan, R. Molo
    DELTA, Dortmund, Germany
  • P.M. Salen, P. van der Meulen
    FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden
 
  Funding: Supported by Federal Ministry of Education and Research of Germany under contract No. 05K10PE1, 05K10PE3, 05K13GU4 and 05K13PE3 and the German Research Foundation programme graduate school 1355.
For seed­ing of a free-elec­tron laser, the spa­tial and tem­po­ral over­lap of the seed laser pulse and the elec­tron bunch in the mod­u­la­tor is crit­i­cal. To es­tab­lish the tem­po­ral over­lap, the time dif­fer­ence be­tween pulses from the seed laser and spon­ta­neous un­du­la­tor ra­di­a­tion is re­duced to a few pico-sec­onds with a com­bi­na­tion of a pho­to­mul­ti­plier tube and a streak cam­era. Fi­nally, for the pre­cise over­lap the im­pact of the seed laser pulses on the elec­tron bunches is ob­served. In this con­tri­bu­tion, we de­scribe the cur­rent ex­per­i­men­tal setup, dis­cuss the tech­niques ap­plied to es­tab­lish the tem­po­ral over­lap and an­a­lyze its sta­bil­ity.