4GLS and ERLP at Daresbury Hywel Owen Accelerator Science and Technology Centre
UK Synchrotron Radiation Provision diamond: operational 2007 onwards SRS: operational 1980 to 2008 (storage ring commissioning underway) 2 nd -gen Storage Ring, 2 GeV, 250 mA 3 rd -gen, 3 GeV, 300 mA ESRF The UK wants a suite of IR to � 3 rd -gen, 6 GeV XUV short-pulse sources to complement what is available to UK users. Hywel Owen, CASA Seminar 12 th June 2007
The 4GLS Concept Hywel Owen, CASA Seminar 12 th June 2007
4GLS Branches and Bunch Paths Hywel Owen, CASA Seminar 12 th June 2007
4GLS: Photon Output Coverage and Repetition Rates 1 kHz 4.3 MHz 13 MHz 1.3 GHz (~CW) Spontaneous SR Range: up to 1keV Pulse length: few ps down to 100 fs Repetition rates: 1.3 GHz/6.5 MHz/1 kHz Hywel Owen, CASA Seminar 12 th June 2007
4GLS IR-FEL 2.5 to 200 μ m � Oscillator FEL � SCRF for stability � 25 to 60 MeV � Investigating new request � for 2 simultaneous IR FEL Beams Ignore these quads! Hywel Owen, CASA Seminar 12 th June 2007
XUV-FEL Branch 1 nC, 750 MeV, 2 mm mrad normalised emittance, 1 kHz, 1.5 kA Hywel Owen, CASA Seminar 12 th June 2007
XUV-FEL Compression Scheme Main linac compression scheme We must perform a long bend after � all the acceleration 1 nC/1kHz Keep the bunch long to minimise 80 pC/1.3GHz � CSR No final chirp � ~10° Small final energy spread � Therefore need strong � ~20° E compression at the end (get CSR (~40 ps) again) R 56 >0 R 56 <0 Looking at the � spreader/diagnostics concept at t the moment (1FEL to 2) FEL INJECTOR MERGE/BC1 210 MeV SPREADER SPREADER 750 MeV 210 MeV 1.4 ps R 56 = 0.12 m σ E <0.1% R 56 = 0.0 m FEL ARC FEL ARC 750 MeV <1.4 ps R 56 >0.4 m FEL 1 σ E 0.1% Matching/Diagnostics 750 MeV ~200 fs/1.5 kA FEL 2 σ E 0.1% BC2 Hywel Owen, CASA Seminar 12 th June 2007
XUV-FEL Microbunching Z. Huang and Peter Williams Hywel Owen, CASA Seminar 12 th June 2007
High Average Current Loop – the ERL part 100mA, 550 MeV, 2 mm-mrad normalised emittance 1.3 GHz, 77 pC, CW 10 MeV 10 MeV 2 mm-mrad Decompression and path adjustment ~100 fs ~500 fs FODO Compression Channel 550 MeV Undulator sources + VUV-FEL Progressive compression, ~500 fs to 100 fs Hywel Owen, CASA Seminar 12 th June 2007
4GLS Parameters (Present Configuration) Bunch Parameter XUV-FEL 100 mA VUV-FEL IR-FEL HACL HACL Operation Operation Electron Energy (MeV) 750 550 550 25 to 60 Normalised Emittance 2 2 2 10 (mm mrad) RMS Projected Energy 0.1 % 0.1 % 0.1 % 0.1 % Spread RMS Bunch Length < 270 fs 100 to 900 100 fs 1 to 10 ps fs Bunch Charge 1 nC 77 pC 77 pC 200 pC Bunch Repetition Rate 1 kHz 1.3 GHz n x 4.33 MHz 13 MHz Electron Beam Average <1 kW 55 MW n x 183 kW <156 kW Power Hywel Owen, CASA Seminar 12 th June 2007
Beam Separation Concept 3 2 3 0 A 2 5 6 0 10,0° 8,0° 4 0 0 1000 4,0° 750 MeV A 2895 7 0 0 4,0° 3 4 8 5 6 0 Spreader dipole 0 M e V A-A 10 Spectrometer + spreader dipole � (instead of septa or chicane/slide) 10 20 50 � 35 Single (possibly PM) dipole with � opposing fields in each aperture 80 cf. LHC dipoles � Needs engineering study and � Much longer consideration of beam loss/radiation 600 MeV damage 750 MeV Hywel Owen, CASA Seminar 12 th June 2007
XUV/HACL Outward Arc Transport SC SC cavity cavity 35 75 250 Solenoid pair 2 2 180° apart 6 6 , , 4 4 1 1 HACL/XUV-FEL Magnetic Separator 750 MeV Undulator Undulator 550 MeV XUV-FEL Separator ~60 cm ~ 4 degrees HACL Hywel Owen, CASA Seminar 12 th June 2007
4GLS – Engineering Concept for XUV and HACL Transport XUV-FEL traverses ~60cm above HACL arcs Hywel Owen, CASA Seminar 12 th June 2007
4GLS Possible Sites Daresbury Village Daresbury Science Park Keckwick Hill SuperSTEM ERLP SRS A HPCx Old Cockcroft Institute/ASTeC Expressway Part of UK restructured Research Councils (‘Large Facilities Research Council’) Hywel Owen, CASA Seminar 12 th June 2007
4GLS Building Concept Hywel Owen, CASA Seminar 12 th June 2007
Outward Arc Transport Building size restrictions/cost � SC cavity mean: FEL arc outside of CW arc � Advantages: � Keeps FEL arc radius large for 2 � 6 , 4 Solenoids must CSR management 1 be 180 degrees Eliminates opposing bends apart. � Disadvantages: � Vertical offset to transport to Note final � compensating bend pass FEL arc over CW loop arc – 60 cm in present iteration Uses solenoids to achieve Undulator � vertical matching – no flat FEL arc decompresses beams for FEL branch � HACL arc compresses Optically complex! � � Hywel Owen, CASA Seminar 12 th June 2007
HACL Progressive Compression Concept (CDR Configuration) R 56 ~ 0.5 m Standard Mode (Progressive/VUV) All Short (Wakefield Limit) R 56 ~ 0 – 1 cm per cell Possible Alternative Mode Hywel Owen, CASA Seminar 12 th June 2007
Resistive Wall Wakefields The Effect of Wakefields Cu, 1 nC, 50 fs 1/r 3 (In reality bunches will not be Gaussian) Hywel Owen, CASA Seminar 12 th June 2007
HACL Pseudo-S2E Simulation (CDR Configuration) T 566 R 56 (~1cm per cell) Hywel Owen, CASA Seminar 12 th June 2007
4GLS VUV-FEL 3 to 10 eV, ~500MW output � Regenerative Amplifier system � 4.33 MHz compared with 1 kHz XUV FEL � Very tolerant to mirror degradation � Reflectivity only 40 to 60% needed � No seed electrons � 300 A peak current � Hywel Owen, CASA Seminar 12 th June 2007
4GLS Dual-Phase Compression Concept Main linac compression scheme 1 nC/1kHz 80 pC/1.3GHz ~10° ~20° Longitudinal cavity wake from (~40 ps) complete main linac 1 nC@40ps gives ~50 kV shift to 80 pC bunch (~10-4 at 600 MeV) R 56 >0 R 56 <0 Hywel Owen, CASA Seminar 12 th June 2007
Signs of Compression Only the phases and signs of compression are different Hywel Owen, CASA Seminar 12 th June 2007
Polarity of R56 – A and B Type Compression ( ) η = ∫ s A – Arc-like B – BC-like R ds ( ) ρ 56 s R 56 <0 R 56 >0 A chirp goes with A compression B chirp goes with B compression Your sign convention is up to you! Wakefield and CSR Issues can help you choose which way round! Hywel Owen, CASA Seminar 12 th June 2007
Higher-Harmonic or Sextupoles? At first glance, higher- � harmonic and T566 correction look pretty equivalent This is true unless you are � really pushing your parameters Consider a toy system � 10 to 100 MeV � Single stage � T566 or 3 rd harmonic � All parameters optimised � Third harmonic is more � effective at linearising than T566 Hywel Owen, CASA Seminar 12 th June 2007
What happens with a longer bunch length? T566 (Sextupoles) Third Harmonic 10x smaller bunch length! This behaviour is probably generally true � If you want to use sextupoles, then you have to keep your input (injector) bunch � length short 4GLS HACL injector meets these requirements – about 2ps/0.4% at 10 MeV � Hywel Owen, CASA Seminar 12 th June 2007
HACL v1.1 � No lasing � (1D Model) Hywel Owen, CASA Seminar 12 th June 2007
HACL v1.1 � Lasing � (1D model) Hywel Owen, CASA Seminar 12 th June 2007
HACL BBU Threshold 4GLS will use 7-cell cavities adapted from TESLA 9-CELL cavities � These have been modelled in Microwave Studio � For more accurate modelling the couplers and dampers must be � included BBU threshold depends on HOMs and focusing scheme � Using doublet scheme similar to Cornell ERL (half-half) � See more detailed talk by Emma Wooldridge � Hywel Owen, CASA Seminar 12 th June 2007
Collimation in 4GLS Hywel Owen, CASA Seminar 12 th June 2007
4GLS Shielding and Interlocks Hywel Owen, CASA Seminar 12 th June 2007
Normal conductive 1.5-cell RF photocathode gun 2400 60.0 2000 40.0 Focusing magnetic field Accelerating electric field Magnetic field, a.u. 1600 20.0 Electric field, a.u. 1200 0.0 800 -20.0 400 -40.0 0 -60.0 0 0.2 0.4 0.6 0.8 1 Longitudinal position, m. Distribution of accelerating RF and focusing magnetic field in the gun Hywel Owen, CASA Seminar 12 th June 2007
ASTRA simulation of the XUV-FEL injector B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007 Hywel Owen, CASA Seminar 12 th June 2007
ASTRA simulation of the XUV-FEL injector B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007 Hywel Owen, CASA Seminar 12 th June 2007
VUV-FEL injector Beam parameters at the entrance of main linac Bunch charge, pC 77 Bunch repetition rate, GHz 1.3 Operation mode CW Beam energy, MeV 10 Normalised beam emittance, π ·mm·mrad < 2 Uncorrelated energy spread, % < 0.2 2 Bunch length, ps Hywel Owen, CASA Seminar 12 th June 2007
High voltage DC photocathode gun Parameter of the photocathode gun Gun voltage, kV 500 Average beam current, mA 100 Bunch repetition rate, GHz 1.3 RMS laser pulse length, ps 20 Laser pulse shape Gaussian Estimated operational life time, hours 27 Estimated rms transverse emittance, π ·mm·mrad 2.8 Estimated rms bunch Length, ps 30 B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007 Hywel Owen, CASA Seminar 12 th June 2007
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