TY  - CONF
AU  - Huang, P.W.
AU  - Chen, Y.
AU  - Filippetto, D.
AU  - Good, J.D.
AU  - Groß, M.
AU  - Isaev, I.I.
AU  - Koschitzki, C.
AU  - Krasilnikov, M.
AU  - Lal, S.
AU  - Li, X.
AU  - Lishilin, O.
AU  - Melkumyan, D.
AU  - Niemczyk, R.
AU  - Oppelt, A.
AU  - Qian, H.J.
AU  - Sannibale, F.
AU  - Shaker, H.
AU  - Stephan, F.
AU  - Tang, C.-X.
AU  - Vashchenko, G.
AU  - Wan, W.
ED  - Boland, Mark
ED  - Tanaka, Hitoshi
ED  - Button, David
ED  - Dowd, Rohan
ED  - Schaa, Volker RW
ED  - Tan, Eugene
TI  - SINGLE SHOT CATHODE TRANSVERSE MOMENTUM IMAGING IN PHOTOINJECTORS
J2  - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019
CY  - Melbourne, Australia
T2  - International Particle Accelerator Conference
T3  - 10
LA  - english
AB  - In state of the art photoinjector electron sources, cathode performance determines the lower limit of achievable beam emittance. Measuring the thermal emittance at the photocathodes in electron guns is of vital importance for improving the injectors. Traditional methods, like solenoid scan, pepper-pot, need multi-shots and are time-consuming, therefore suffer from machine stability. Here we propose a new method, named cathode transverse momentum imaging. By tuning the gun solenoid focusing, the electrons’ transverse momentum at the cathode is imaged to a downstream screen, which enables a single shot measurement. Several experiments have been done at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) with a Cs2Te cathode. Measurements of cathode transverse momentum, the corresponding spectra, cathode transverse momentum map and its correlation with surface electric field are presented.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 1964
EP  - 1967
KW  - cathode
KW  - solenoid
KW  - emittance
KW  - electron
KW  - simulation
DA  - 2019/06
PY  - 2019
SN  - 978-3-95450-208-0
DO  - DOI: 10.18429/JACoW-IPAC2019-TUPTS014
UR  - http://jacow.org/ipac2019/papers/tupts014.pdf
ER  - 

TY  - CONF
AU  - Yang, X.
AU  - Doom, L.
AU  - Fedurin, M.G.
AU  - Hidaka, Y.
AU  - Li, J.J.
AU  - Padrazo Jr, D.
AU  - Shaftan, T.V.
AU  - Smaluk, V.V.
AU  - Wan, W.
AU  - Wang, G.M.
AU  - Yu, L.-H.
AU  - Zhu, Y.
ED  - Boland, Mark
ED  - Tanaka, Hitoshi
ED  - Button, David
ED  - Dowd, Rohan
ED  - Schaa, Volker RW
ED  - Tan, Eugene
TI  - Tuning Quadrupoles for Brighter and Sharper Ultra-fast Electron Diffraction Imaging
J2  - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019
CY  - Melbourne, Australia
T2  - International Particle Accelerator Conference
T3  - 10
LA  - english
AB  - We report our proof-of-principle design and experi-mental commissioning of broadly tunable and low-cost transverse focusing lens system for MeV-energy electron beams at the ultra-fast electron diffraction (UED) beam-line of the Accelerator Test Facility II of BNL. We exper-imentally demonstrate the independent control over the size and divergence of the electron beam at the sample via tunable quadrupoles. By applying online optimiza-tion, we achieve minimum beam sizes 75 µm from 1 to 13 pC, two orders of magnitude higher charge density than previously achieved using conventional solenoid tech-nique. Finally, we experimentally demonstrate Bragg-diffraction image (BDI) with significant improvement up to 3 times brighter and 2 times sharper BDI peaks via the optimized quadrupoles, improvement larger with higher charge. The result could be crucial for the future single-shot ultra-fast electron microscope development.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 3571
EP  - 3573
KW  - quadrupole
KW  - electron
KW  - focusing
KW  - experiment
KW  - solenoid
DA  - 2019/06
PY  - 2019
SN  - 978-3-95450-208-0
DO  - DOI: 10.18429/JACoW-IPAC2019-THPMP053
UR  - http://jacow.org/ipac2019/papers/thpmp053.pdf
ER  -