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 DresdenJ.Teichert@fzd.de

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