The Next Generation Light Source Test Facility at Daresbury Jim Clarke ASTeC, STFC Daresbury Laboratory Ultra Bright Electron Sources Workshop, Daresbury, June 2011 Context: NLS UK FEL Project 1. Photon energy range and tunability: 50 300 eV 250 850 eV 430 1000 eV 2. Repetition rate: 1 kHz with an upgrade path to 1 MHz 3. Pulse length & pulse energy: 20 fs FWHM photon pulse length at all photon energies photons/pulse at 1 keV upgrade path to sub-fs pulses 4. Transverse and longitudinal coherence 5. Polarisation: FEL1 & FEL2: complete polarisation control FEL3: at least horizontal and circular polarisation over the full range eV. NLS Layout 2.25 GeV, 1 kHz rep rate increasing in phases to 1MHz 3 independent FELs with variable gap undulators SC Linac FEL Hall Layout Science Case and CDR Strong science case developed and accepted, published July 2009 The CDR was published in May 2010 But project put on hold for 3 to 5 years UK maintains clear ambition for a next generation light source Reports and more information available at Next Step Take advantage of the project pause to carry out targeted R&D A key part of this will be a light source test facility To test new ideas and concepts Enhanced radiation output (short pulses, coherence, high harmonics, stability,...) New technologies (diagnostics, synchronisation, LLRF, undulators,...) More compact solutions more economic... To reduce the risks for a future light source facility (time, cost, quality) Ultimate Aim To develop a normal conducting test accelerator able to generate longitudinally and transversely bright electron bunches and to use these bunches in the experimental production of stable, synchronised, ultra short photon pulses of coherent light from a single pass FEL with techniques directly applicable to the future generation of light source facilities. Stable in terms of transverse position, angle, and intensity from shot to shot. A target synchronisation level for the photon pulse arrival time of better than 10 fs rms is proposed. In this context ultra short means less than the FEL cooperation length, which is typically ~100 wavelengths long (i.e. this equates to a pulse length of 400 as at 1keV, or 40 as at 10 keV). A SASE FEL normally generates pulses that are dictated by the electron bunch length, which can be orders of magnitude larger than the cooperation length. Other Aims and Prerequisites To lead the development of low charge single bunch diagnostics, synchronisation systems, advanced low level RF systems, and novel short period undulators. To develop skills and expertise in the technology of NC RF photoinjectors and seed laser systems. To develop novel techniques for the generation and control of bright electron bunches manipulation by externally injected radiation fields mitigation against unwanted short electron bunch effects (e.g. microbunching and CSR). To demonstrate high temporal coherence and wavelength stability of the FEL, for example through the use of external seeding or other methods. To develop the techniques for the generation of coherent higher harmonics of a seed source. To develop new photon pulse diagnostic techniques as required for single shot characterisation and arrival time monitoring. Fixing the Parameters... If we define... Shortest wavelength Longest wavelength Minimum undulator gap Minimum undulator parameter a w...this then defines the undulator period and required beam energy to tune over this wavelength range in a single undulator Longest wavelength is at minimum gap and shortest wavelength is at maximum gap (min a w ) We know we might want resonant interactions with 800nm + harmonics OPA at ~ 5um HHG at 100nm 50nm So these are the wavelengths of interest... Need to set energy/period to give us access to these wavelengths and some tunability across them 1. Assume 8mm Gap, a w > Tune from OPA at 5um to Ti:Sa at 800nm: 96MeV / 38mm Tune between 3 rd and 5 th Harmonic of Ti:Sa: 170MeV / 24mm 3 Resonance with HHG at 100nm, no tunability: 190MeV / 19mm 4 Resonance with HHG at 50nm, no tunability: 268MeV / 19mm 5 Tune between 100nm and 50nm: 315MeV / 26mm At 100MeV, minimum wavelength is 370nm At 200MeV can just reach 100nm 2. More aggressive: 4mm gap, a w > Tune from OPA at 5um to Ti:Sa at 800nm: 75MeV / 28mm Tune between 3 rd and 5 th Harmonic of Ti:Sa: 126MeV / 16mm 3 Resonance with HHG at 100nm, no tunability: 133MeV / 11mm 4 Resonance with HHG at 50nm, no tunability: 189MeV / 11mm 5 Tune between 100nm and 50nm: 237MeV / 17mm At 100MeV, minimum wavelength is 185nm At 200MeV can reach 50nm Emittance Requirement 4 Genesis Modelling (SS) 250 MeV 100nm 60 keV energy spread 290A 1mm mrad Preliminary Parameters Beam Energy ~250 MeV SASE Saturation length