Brief overall description of the Task WP12.5 - PowerPoint Presentation

Slide1

Brief overall description of the Task WP12.5

Photocathodes

for the reporting period: 1.05.2013 – 30.04.2014Slide2

Evaluate Pb photocathode deposition for improved performance of SRF guns

Characterise and optimise performance of Diamond Amplifier Cathode solutions for SRF guns

Material R&D for advanced photo cathodes for NC RF guns

Fields of interest:

Actions and institutions:

WP12.5 Brief overall descriptionSlide3

Milestones

Deliverables

WP12.5 Brief overall descriptionSlide4

Kick off Meeting Task 12.5 on RF Photocathodes at HZB

on 12.07.2013

WP12.5 Brief overall description

http://eucard2.web.cern.ch/content/work-packagesSlide5

Q.E.

th. Emittance

(low E char.)

field emission &

roughness

surface &

layer

properties

gun

performance

beam param.

Preparation

Test stand

at Swierk

QE vs λ with D –tube since March 14

since January 14

SEM

Grazing-XRD

 HV Cath. Arc Pb coatingHZDRSRF gun access until March ´14 no test of „dangerous“ cathodes in the „new“ gun „old“ gun as a future tes bench? QE in gun, RF properties, dark currentbeam parameters HZDRprep. systemQE (260 nm)QE scan, QE(λ)laser cleaning?     HZB HoBiCaT& GunNo access to HoBiCaT for further gun cavity testsGun 1 ready in autumn ´14, but very tight R&D schedule  HZBFE TestbenchTransverse. Therm. emittancefield emissionmapping for all cathodes (  BESSY II(beamtime application)Energy distribution with ARPES In situ XPS, and other SR methodesall cathodes  DESYTest stands SAFEM ? Q vs EChechiaDark current STFC QE at λ =const tUV transverseEnergy analysis GaAs, Metallic Photocath.AFM for roughness only (in commissioning)AES, XPS, multiprobeCLARA gun In developementGaAs preparation facilityMetal photocath. PVD

WP12.5 Brief overall description

CapabilitiesSlide6

Work on Subtask 12.5.1 Pb photocathode deposition

HZDR fabricated, polished and shiped four Nb plugs for Pb deposition to NCBJ Swierk. The plugs are deposited there with 2 µm Pb. Next step is laser cleaning (needs help of NCBJ)and quantum efficiency

measurement at 252 nm in the photocathode preparation system at HZDR. (work for Delivery D12.9 in 3/2016)

Work on Subtask 12.5.2 Diamond amplifier cathod

e development. Contact to BNL on requirements for integration in SRF gun.

The goal of our task is to study next generation photocathodes delivering

high brightness, high average current electron beams. We want to investigate wanted and unwanted beam properties and work on the

i

ntegration

of the photocathode into the SRF gun

enviroment

. Candidates

for next generation cathodes include Diamond Amplifier Cathodes (

DAC

)

and Diamond Field Emitte Arrays (DFEA). Helmholtz Zentrum Dresden RossendorfWP12.5 Brief overall descriptionSlide7

WP12.5 Brief overall description

F

ield

Emission

Laboratory

:

Test dark current emission from substrates and cathode films under high electric DC fields

Current

measurement

Image

of

the

emitters

on

the view screenConstant gap d=0.4 mmGradient can be changed by controllingbias voltage (Umax=10 kV)Setup complete and under vacuum, first tests with diamond field emitter array cathodes (collaboration University Vanderbildt) and Mo substrates. Next step is commissioning with 5 kV DC voltage, then increasing up to 10 kV voltage (at 0.4 mm gap  25 MV/m).Helmholtz Zentrum BerlinSlide8

Status of the

SRF

-gun cavity with plug at

DESY

Gasket made of In foil

Deutsches

Elektronen

Synchrotron

WP12.5 Brief overall description

see the further presentation

Further information will be provided by W Grabowski of NCBJ SwierkSlide9

WP12.5 Brief overall description

AFM

LEED

X-ray Gun

Analyser

UHV Vacuum System

A multi-chamber ultra-high vacuum system has been constructed and equipped with a number of surface analysis techniques

.

The commissioning of the SAPI system is a key milestone in this sub-task and has been reported as CERN-ACC-2014-0039

Work is now progressing on the investigation of a series of alternative metal photocathode materials using the facilities at

Daresbury

.

Surface Analysis/Preparation Installation (SAPI)

Science & Technology Facilities Council, Cockroft Inst

.

see the further presentationSlide10

WP12.5 Brief overall description

Narodowe Centrum Badań Jądrowych, Świerk

UHV arc deposition devices

Pb/Nb layers post-

processing

IBIS rod plasma injector

Probe heater for vacuum

annealling

Short arc device

Filtered UHV arc system

Surface analysis; photocathode tests

SEM laboratory

Photocathode diagnostic

stand – under constructionSlide11

WP12.5 Brief overall description

Thank you for your attention !