Author: Werin, S.
Paper Title Page
MOPAB266 Start-to-End Study on Laser and RF Jitter Effects for MAX-IV SXL 844
 
  • S.P. Pirani, B.S. Kyle
    MAX IV Laboratory, Lund University, Lund, Sweden
  • F. Curbis, M.A. Pop, S. Werin
    Lund University, Lund, Sweden
  • W. Qin
    DESY, Hamburg, Germany
  
  A Soft X-ray free elec­tron laser (FEL) for the MAX IV Lab­o­ra­tory is cur­rently in the de­sign phase and it will use the ex­ist­ing 3 GeV linac. Pre­sent sta­bil­ity lim­its in the RF and the pho­to­cath­ode laser will af­fect the per­for­mance of the FEL. One of the crit­i­cal el­e­ments for the de­sign of a FEL is to have an es­ti­ma­tion on jit­ter ef­fects of the ac­cel­er­a­tor pa­ra­me­ters on the X-ray ra­di­a­tion. In this re­gard, we im­ple­mented a start-to-end study using Astra, El­e­gant and Gen­e­sis in order to as­sess pos­si­ble vari­a­tions in pulse en­ergy, pho­ton pulse length and spec­tral width in the Soft X-ray Laser (SXL) ra­di­a­tion. This in­ves­ti­ga­tion pro­vides in­sights on the final SXL per­for­mance vari­a­tion due to RF and laser re­lated jit­ter af­fect­ing the elec­tron beam.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB266  
About • paper received ※ 19 May 2021       paper accepted ※ 26 July 2021       issue date ※ 24 August 2021  
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TUPAB082 Analysis of the Effect of Energy Chirp in Implementing EEHG at SXL 1566
 
  • M.A. Pop, F. Curbis, B.S. Kyle, S.P. Pirani, W. Qin, S. Werin
    MAX IV Laboratory, Lund University, Lund, Sweden
  • F. Curbis, S. Werin
    Lund University, Lund, Sweden
  • W. Qin
    DESY, Hamburg, Germany
  
  As a part of the ef­forts to im­prove the lon­gi­tu­di­nal co­her­ence in the de­sign of the Soft X-ray FEL (the SXL) at MAX IV, we pre­sent a pos­si­ble im­ple­men­ta­tion of the EEHG har­monic seed­ing scheme partly in­te­grated into the sec­ond bunch com­pres­sor of the ex­ist­ing LINAC. A spe­cial focus is given to the ef­fect of CSR on the re­sult­ing EEHG bunch­ing and on how this un­wanted ef­fect might be con­trolled.  
poster icon Poster TUPAB082 [1.825 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB082  
About • paper received ※ 15 May 2021       paper accepted ※ 28 July 2021       issue date ※ 17 August 2021  
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TUPAB113 Highlights From the Conceptual Design Report of the Soft X-Ray Laser at MAX IV 1651
 
  • F. Curbis, J. Andersson, L. Isaksson, B.S. Kyle, F. Lindau, E. Mansten, H. Tarawneh, P.F. Tavares, S. Thorin, A.S. Vorozhtsov
    MAX IV Laboratory, Lund University, Lund, Sweden
  • S. Bonetti
    Stockholm University, Stockholm, Sweden
  • V.A. Goryashko, P.M. Salén
    Uppsala University, Uppsala, Sweden
  • P. Johnsson, S.P. Pirani, M.A. Pop, W. Qin, S. Werin
    Lund University, Lund, Sweden
  • M. Larsson
    Stockholm University, Department of Physics, Stockholm, Sweden
  • A. Nilsson
    FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden
  • J.A. Sellberg
    KTH Physics, Stockholm, Sweden
  
  Funding: Knut and Alice Wallenberg Foundation
The SXL (Soft X-ray Laser) pro­ject de­vel­oped a con­cep­tual de­sign for a soft X-ray Free Elec­tron Laser in the 1–5 nm wave­length range, dri­ven by the ex­ist­ing MAX IV 3 GeV linac. In this con­tri­bu­tion we will focus on the FEL op­er­a­tion modes de­vel­oped for the first phase of the pro­ject based on two dif­fer­ent linac modes. The de­sign work was sup­ported by the Knut and Alice Wal­len­berg foun­da­tion and by sev­eral Swedish uni­ver­si­ties and or­ga­ni­za­tions (Stock­holm, Up­p­sala, KTH Royal In­sti­tute of Tech­nol­ogy, Stock­holm-Up­p­sala FEL cen­ter, MAX IV lab­o­ra­tory and Lund Uni­ver­sity). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB113  
About • paper received ※ 19 May 2021       paper accepted ※ 17 June 2021       issue date ※ 19 August 2021  
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TUPAB198 ESS DTL Tuning Using Machine Learning Methods 1872
 
  • J.S. Lundquist, N. Milas, E. Nilsson
    ESS, Lund, Sweden
  • S. Werin
    Lund University, Lund, Sweden
  
  The Eu­ro­pean Spal­la­tion Source, cur­rently under con­struc­tion in Lund, Swe­den, will be the world’s most pow­er­ful neu­tron source. It is dri­ven by a pro­ton linac with a cur­rent of 62.5 mA, 2.86 ms long pulses at 14 Hz. The final sec­tion of its nor­mal-con­duct­ing front-end con­sists of a 39 m long drift tube linac (DTL) di­vided into five tanks, de­signed to ac­cel­er­ate the pro­ton beam from 3.6 MeV to 90 MeV. The high beam cur­rent and power im­pose chal­lenges to the de­sign and tun­ing of the ma­chine and the RF am­pli­tude and phase have to be set within 1% and 1 de­gree of the de­sign val­ues. The usual method used to de­fine the RF set-point is sig­na­ture match­ing, which can be a time con­sum­ing and chal­leng­ing process, and new tech­niques to meet the grow­ing com­plex­ity of ac­cel­er­a­tor fa­cil­i­ties are highly de­sir­able. In this paper we study the usage of Ma­chine Learn­ing to de­ter­mine the RF op­ti­mum am­pli­tude and phase. The data from a sim­u­lated phase scan is fed into an ar­ti­fi­cial neural net­work in order to iden­tify the needed changes to achieve the best tun­ing. Our test for the ESS DTL1 shows promis­ing re­sults, and fur­ther de­vel­op­ment of the method will be out­lined.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB198  
About • paper received ※ 17 May 2021       paper accepted ※ 21 June 2021       issue date ※ 13 August 2021  
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TUPAB103 Discussion on CSR instability in EEHG Simulation 1622
 
  • D. Samoilenko, W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • F. Curbis, M.A. Pop, S. Werin
    MAX IV Laboratory, Lund University, Lund, Sweden
  • P. Niknejadi, G. Paraskaki
    DESY, Hamburg, Germany
  • F. Pannek
    University of Hamburg, Hamburg, Germany
  
  Echo-En­abled Har­monic Gen­er­a­tion (EEHG) is an ex­ter­nal seed­ing tech­nique for XUV and soft X-ray Free Elec­tron Lasers (FEL). It has re­cently been ex­per­i­men­tally demon­strated and cur­rently many fa­cil­i­ties world­wide in­tend to in­cor­po­rate it in user op­er­a­tion. The EEHG process re­lies on very ac­cu­rate and com­plex trans­for­ma­tions of elec­tron beam phase space by means of a se­ries of un­du­la­tors cou­pled to lasers and dis­per­sive chi­canes. As a re­sult of the phase space ma­nip­u­la­tion, elec­trons are bunched at a high har­monic of the seed laser wave­length al­low­ing co­her­ent emis­sion at few nm wave­length. Dis­per­sion oc­cur­ring in strong chi­canes is im­per­a­tive for im­ple­men­ta­tion of this scheme and ef­fec­tive elec­tron bunch­ing gen­er­a­tion. How­ever, strong chi­canes at the same time can be source of beam in­sta­bil­ity ef­fects, such as Co­her­ent Syn­chro­tron Ra­di­a­tion (CSR), that can sig­nif­i­cantly grow in these con­di­tions and sup­press the bunch­ing process. There­fore, there is a com­mon need to in­ves­ti­gate such ef­fects in de­tail. Here, we dis­cuss their treat­ment with sim­u­la­tion codes ap­plied to a typ­i­cal EEHG setup.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB103  
About • paper received ※ 19 May 2021       paper accepted ※ 17 June 2021       issue date ※ 12 August 2021  
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