... 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 !!
EMMA
superconducting linac DC gun
photoinjectorlaserFree Electron
Laser
superconductingbooster
The ALICE Facility @ Daresbury Laboratory
Accelerators and Lasers In Combined Experiments
An accelerator R&D facility based on a superconducting energy recovery linac
ALICE Machine Description
DC Gun + Photo Injector Laser230 kV GaAs cathode Up to 100 pC bunch charge Up to 81.25 MHz rep rate
RF SystemSuperconducting booster + linac9-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 isochronousBunch compression chicane R56 = 28 cm
Diagnostics
YAG/OTR screens + stripline BPMs
Electro-optic bunch profile monitor
UndulatorOscillator type FEL.Variable gap
TW laserFor Compton Backscatteringand EO~70 fS duration, 10 HzTi 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
Cat
hode
Ano
de
GateValve
Ligh
t Box
BPM-01
SOL-01VCOR-01HCOR-01
Buncher
A BFC 1
Tran
sver
seK
icke
r
C
DE
FC 2Dimensions: Survey data (A0-183-11686 dated 14/07/06)
ERLP Injector test beamline v2.5 (29/08/2006)
SOL-02VCOR-02HCOR-02
VCOR-06HCOR-06 YAG-01
3030
50
HSLT-01 VSLT-01
50
-22 200
-59 500
30-16 500
-54 060
-55 400
-18 500
-60 260
-22 700
ANMAG-01
YAG-02
YAG-03 YAG-04
"a"
Sections schematics when looking downstream (i.e. from the gun)
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 !
2009: further milestones : THz
Coherently enhanced broadband THz radiation generated (Feb)
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
0 2 4 6 8 10
#1016
THz, V
TH
z, V
Q, pC
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
ScintillatorBe window
Interaction region
2009: further milestones : CBS exp.
2010: “accelerating”
He processing by ASTeC RF + cryogenic groups with assistance from T. Powers (Jlab)
0
100
200
300
400
500
600
700
800
4 5 6 7 8 9 10 11 12
RA
DIA
TIO
N,
uSv/
h
ACCELERATING GRADIENT, MV/m
• 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)
23rd October 2010: ALICE FEL First Lasing
First Lasing Data: 23/10/10
-5 0 5 10 15 20 250
2
4
6
8
10
12
14
Cavity Length Detuning (m)
Out
coup
led
Ave
rage
Po
wer
(m
W)
Lasing 100-40 pC @ 16.25 MHz
5 5.5 6 6.5 7 7.5 8 8.50
0.2
0.4
0.6
0.8
1
P(
)(a
.u.)
(m)
g = 16 mmg = 15 mmg = 14 mmg = 13 mmg = 12 mm
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
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