Institute of Radiation Physics Jochen Teichert www.fzd.de Forschungszentrum Dresden-Rossendorf
Radiation Source ELBE
Jochen Teichert
Forschungszentrum Dresden-RossendorfInstitut für StrahlenphysikStrahlungsquelle ELBE
PF 510119, 01314 [email protected]
The SRF Photoinjector at ELBEa Test Bench for
Future Studies and Developments
ESGARD OMIA meeting, 11.09.07
Institute of Radiation Physics Jochen Teichert www.fzd.de Forschungszentrum Dresden-Rossendorf
Radiation Source ELBE
Development of a SCRF Photoinjectorhigh brightness & high average current
Supported by EU within CARE/PHINand the German BMBF with DESY, BESSY, MBI
Background
Institute of Radiation Physics Jochen Teichert www.fzd.de Forschungszentrum Dresden-Rossendorf
Radiation Source ELBE
Installation at ELBE and Commissioning in Summer 2007
cryostat vessel
He supply tube
emittance compensation
solenoid
beam dumpLaser input port
Background
Institute of Radiation Physics Jochen Teichert www.fzd.de Forschungszentrum Dresden-Rossendorf
Radiation Source ELBE
First operating prototype SRF Photoinjector at an accelerator facility
SRF Photoinjector test bench
Background
Institute of Radiation Physics Jochen Teichert www.fzd.de Forschungszentrum Dresden-Rossendorf
Radiation Source ELBEProposed SRF-AS Activities
R1laser pulse shapingImprovement of the driver laser system,
temporal and spatial laser pulse shaping
R2 JRA1improved SCRF gun cavitydesign optimization for higher gradients, simplification,
Use of large grain Nb
R3
JRA2
emittance compensation studiesStudy of emittance compensation schemes,
Use of ELBE for slice emittance measurements
R4SCRF gun for polarized electronsStudy of advanced photocathodes with high Q.E.
especial. GaAs for polarized electrons
R5
SCRF gun measurementsExperm. Studies with respect to future application,
Higher average currents for ERLs
SCRF gun for Compton-back-scattering x-ray production
Institute of Radiation Physics Jochen Teichert www.fzd.de Forschungszentrum Dresden-Rossendorf
Radiation Source ELBEJRA1 – SC Cavities
R2 Improved SCRF gun cavity• strong field emission at comparably low gradients problem: surface probably polluted due to uncleaned choke filter –insufficient HPR results
High brightness requireshigh acceleration gradient
εn = 1 µm @ 1 nC needs 50 MV/m peak field
New SRRF gun cavity-Optimization of cavity shape with respect to BCP and HPR-Simplification tuner, HOM coupler-Improvement LF detuning, He-pressure- Large grain Nb
Institute of Radiation Physics Jochen Teichert www.fzd.de Forschungszentrum Dresden-Rossendorf
Radiation Source ELBEJRA2 – Accelerator and Beam Studies
R3 Emittance compensation studies
Instead of the SolenoidAround the cavity atNC RF photoinjectors:
• Solenoid downstream
• RF focusing by backtracked or/and shaped cathode
• TE mode in cavity
All methods have to beexperimentally proofed
Slice emittance measurement with correlatedEnergy spread and spectrometer at ELBE
T. Kamps, BESSY Berlin
Institute of Radiation Physics Jochen Teichert www.fzd.de Forschungszentrum Dresden-Rossendorf
Radiation Source ELBEJRA2 – Accelerator and Beam Studies
R4 SCRF gun for polarized electronsRF photo injectors produces e-beams withthe highest brightness butThey cannot produces polarized electrons(bad vacuum in the NC Cu-cavtiy) up to now onlyDC-photoinjectors can use GaAs cathodes
alternative for the ILS electron source The SCRF gun is like a cryo-pump
• Improvement of the cathode transfer and preparation system• Preparation of GaAs photocathodes• Test of the GaAs photocathodes in the SCRF gun
Advantages- green light instead of UV: simplification of lasers for CW, ERL injectors- polarized e- source with lowest emittance for community
- benefit for inverse Compton-scattering experiments at FZD
Institute of Radiation Physics Jochen Teichert www.fzd.de Forschungszentrum Dresden-Rossendorf
Radiation Source ELBEJRA2 – Accelerator and Beam Studies
R5 SCRF gun measurements
SRF gun
7 m
Yb:YAG Power Supply
Injector Power Supply
Linac Power Supply
3 m
SESAM
Yb:YAG Oscillator p
ump diode
Yb:YAG
Pre ampl.
Multi-passYb:YAG Amplifier
Diodes
1.5 mSRF linacSolenoid Collimating
chicanePhotoinjector laser
Focusing quadupoles
LHe RefrigeratorLHe
Dewar
The Rossendorf is the first operating prototype of a SCRF gunHigh brightness – high average current injectors are needed elsewhere:• Injectors for ERL light source – higher current• Injector for BESSY FEL• Compact Compton-back-scattering x-ray source
Test bench for investigation of critical components
W. Graves, MIT
Institute of Radiation Physics Jochen Teichert www.fzd.de Forschungszentrum Dresden-Rossendorf
Radiation Source ELBE
R1laser pulse shapingImprovement of the driver laser system,
temporal and spatial laser pulse shaping
R2improved SCRF gun cavityDESY, Daresbury,
CERN
R3emittance compensation studiesBESSY, DESY, Frascati
R4SCRF gun for polarized electronsDaresbury, SLAC, TU Darmstadt
R5SCRF gun measurementsBESSY, Daresbury,
Collaboration