Presentation on theme: "ERLP / ALICE: a bit of history Yuri Saveliev. ... how all this started SRS DIAMOND ERLP 4GLS... to greener pastures.... Oh yes ! We get there....... Hmmmm."— Presentation transcript:
... how all this started SRS DIAMOND ERLP 4GLS... to greener pastures.... Oh yes ! We get there....... Hmmmm Not quite....
ERLP: test bed and a learning tool New accelerator technologies for the UK First SCRF linac operating in the UK First DC photoinjector gun in the UK First ERL in Europe First IR-FEL driven by energy recovery accelerator in Europe... lots of help from all around the world... BIG THANKS to all and, especially, to colleagues from JLab !!
The ALICE (ERLP) Facility @ Daresbury Laboratory Tower or lab picture
EMMA superconducting linac DC gun photoinjector laser Free Electron Laser superconducting booster The ALICE Facility @ Daresbury Laboratory A ccelerators and L asers I n C ombined E xperiments An accelerator R&D facility based on a superconducting energy recovery linac
ALICE Machine Description DC Gun + Photo Injector Laser 230 kV GaAs cathode Up to 100 pC bunch charge Up to 81.25 MHz rep rate RF System Superconducting booster + linac 9-cell cavities. 1.3 GHz, ~10 MV/m. Pulsed up to 10 Hz, 100 μS bunch trains Beam transport system. Triple bend achromatic arcs. First arc isochronous Bunch compression chicane R 56 = 28 cm Diagnostics YAG/OTR screens + stripline BPMs Electro-optic bunch profile monitor Undulator Oscillator type FEL. Variable gap TW laser For Compton Backscattering and EO ~70 fS duration, 10 Hz Ti Sapphire
ERLP : infancy 2003 - Project conceived and funded - calls for tenders; placing orders started 2004 - PI laser system (commissioning at RAL) - machine specification completed - magnets, IOTs, gun, SF6 vessels, DC HV... 2005 - Gun HV PS assembled -... problems (gun ceramic, buncher etc) - NWSF project starts (TW laser and CBS project)
2006: Gun commissioning & first beam -conditioning resistor failure - gun instability in 260-310kV range of voltages - low and rapidly deteriorating QE (~0.5% max and ~0.1% most of the time) - gun vacuum/current leakage problems after one of the cathode activations FIRST BEAM... and 2K cryogenic system commissioned !
2007: fighting gun problems - strong field emission from the new cathode - rapidly deteriorating QE (from initially >1%) - highly non-uniform QE map (due to wafer heating problems) - mechanical failure inside the cathode ball (flap) New cathode installed - rapid QE deterioration - strong gun contamination after each cathode activation - gun disassembled for wafer change then... vacuum leak discovered Eventually (end of 2007) : The beam from PI gun fully characterised at 350keV > 100pC achieved (QE>3%)
2008: Energy recovery ! Booster cryo modules repair at ACCEL (January-March) Stanford ceramic installed in the PI gun (June) 230kV only First beam through the booster (October) First beam through the linac (December)... And finally... Just before Christmas Full energy recovery (20.8MeV; at a few pC of bunch charge only)
2009: continuous improvements Starting conditions: strong beam loading limitations in SC linacs and strong field emission in main linac ~20pC and ~20MeV pitiful photoelectron cathode lifetime (20pC was a blessing rather than norm ) strong field emitters on cathode and cathode ball (hence 200kV only) Progress: full cathode re-activation and elimination of a minute vacuum leak QE ~ 4% ; >80pC ; long lifetime Kr based “plasma cleaning” of the gun removed the most annoying FE on cathode ball LLRF optimisation to alleviate beam loading 40pC; 81MHz; 100us RF cavities conditioning and RF pulse optimisation operation at up to 30MeV possible !
Compton backscattering demonstrated on ALICE: November 2009... Just two days before the start of the shutdown !!! Electron beam Laser beam X-rays Camera: Pixelfly QE Scintillator Be window Interaction region 2009: further milestones : CBS exp.
2010: “accelerating” He processing by ASTeC RF + cryogenic groups with assistance from T. Powers (Jlab) Helium processing of linac cavities (March) PI laser burst generator allows < 81MHz operation enables Q=60pC as standard THz cells exposures started in April (in an incubator located in the accelerator hall) EMMA ring completed and commissioned... many-many turns (August) IR FEL : first lasing !! (October)
23 rd October 2010: ALICE FEL First Lasing First Lasing Data: 23/10/10 Lasing 100-40 pC @ 16.25 MHz Continuous tuning 5.7-8.0 µm, varying undulator gap. The peak power ~3 MW Single pass gain ~20 %
2011: EMMA First extraction of beam from the ring (March) First acceleration in EMMA (March) Acceleration by EMMA : 12 21MeV (April) Proof-of-principle demonstrated Paper to Nature Physics submitted (and accepted ?)... to be continued First NS FFAG “EMMA”: Successful International Collaboration
2011: FEL and FELIS FEL beam transported to the Diagnostic room (March) Scanning Near-field Optical Microscope (SNOM) installed received from Vanderbuilt Uni. Free Electron Laser integration with Scanning Near-field Optical Microscope FELIS First SNOM image (September) Short e-bunch characterisation with EO diagnostic Electro-optic bunch profile measurement (ZnTe crystal probed by Ti Sapphire laser)
2011: THz for biology THz beam transported to the TCL (Tissue Culture Lab) that’s ~ 30m away from chicane Biological experiments in TCL started (June) Research program to determine safe limits of exposure of human cells to THz and effect of THz on differentiation of stem cells Estimate > 10 KW in single THz pulse with ~ 20% transport efficiency to TCL ALICE : a source of high power broadband coherently enhanced THz radiation
2011: Other developments Quantum dots studies for novel solar cells (with Manchester Uni.) - employs high power THz from ALICE Timing and synchronisation experiments - fibre-ring-laser-based system; - aims for sub-10fs timing distribution for future light sources Digital LLRF development Experiments on interaction of short electron bunches with high power electromagnetic radiation Photocathode research DICC: International collaboration on SC cryomodule development sample fs UV pulse
ALICE Milestones: still growing.... exponentially