TY  - CONF
AU  - Guo, J.
AU  - Fox, J.D.
AU  - Mastoridis, T.
AU  - Rimmer, R.A.
AU  - Wang, H.
AU  - Wang, S.
ED  - Boland, Mark
ED  - Tanaka, Hitoshi
ED  - Button, David
ED  - Dowd, Rohan
ED  - Schaa, Volker RW
ED  - Tan, Eugene
TI  - Transient Beam Loading and Mitigation in JLEIC Collider Rings
J2  - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019
CY  - Melbourne, Australia
T2  - International Particle Accelerator Conference
T3  - 10
LA  - english
AB  - The Jefferson Lab Electron-Ion Collider (JLEIC) is an asymmetric high luminosity ring-ring collider proposed as the next major R&D facility for the nuclear physics community. Both of JLEIC’s electron and ion collider rings have high beam current with gaps serving the pur-poses of beam abort, ion clearing, etc. Such a time-varying beam loading in the RF cavities would generate modulation in cavity RF phase/voltage, causing cyclic shift of collision point and potential luminosity loss. We studied a few approaches to mitigate the RF phase modu-lation and IP shift, such as correcting the RF phase/voltage modulation with traditional LLRF feed-back, one-turn feedback (OTFB), or RF feedforward (FF); optimizing the bunch fill pattern to limit the RF phase/voltage modulation to a small fraction of the bunch trains in the collider ring; or matching the RF phase modulation in the two rings. The preliminary re-sults are discussed in this paper.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 758
EP  - 761
KW  - electron
KW  - cavity
KW  - klystron
KW  - luminosity
KW  - beam-loading
DA  - 2019/06
PY  - 2019
SN  - 978-3-95450-208-0
DO  - DOI: 10.18429/JACoW-IPAC2019-MOPRB080
UR  - http://jacow.org/ipac2019/papers/moprb080.pdf
ER  - 

TY  - CONF
AU  - Simakov, E.I.
AU  - Andrews, H.L.
AU  - Black, D.S.
AU  - Fleming, R.L.
AU  - Kim, D.
AU  - Leedle, K.J.
AU  - Pavlenko, V.N.
ED  - Boland, Mark
ED  - Tanaka, Hitoshi
ED  - Button, David
ED  - Dowd, Rohan
ED  - Schaa, Volker RW
ED  - Tan, Eugene
TI  - Observations of the Femtosecond Laser-Induced Emission From the Diamond Field Emitter Tips
J2  - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019
CY  - Melbourne, Australia
T2  - International Particle Accelerator Conference
T3  - 10
LA  - english
AB  - We present the results of experimental observation of emission from single diamond field emitter tips when triggered by an ultra-short laser pulse. Diamond field emitter array (DFEA) cathodes were originally proposed for applications that require large current densities. DFEAs represent periodic arrays of diamond pyramids with micron-size dimensions and tips with diameters of the order of tens of nanometers. DFEAs are known to produce significant currents in field emission regime under direct current (DC) fields and in radio-frequency (RF) guns. It has been proposed that single diamond tip emitters can be employed for production of small tightly focused electron beams for dielectric laser accelerators (DLAs) that accelerate particles using the energy of light produced by infrared lasers. To generate short electron bunches required by DLAs diamond pyramids may be triggered with a laser. We have recently observed emission produced by a single diamond pyramid when triggered by a laser at different wavelengths from 256 nm to 2020 nm. We have conducted studies with the goal to understand mechanism of the emission. We clearly observed the change in emission mechanism when the wavelength changed from 256 nm to 512 nm. We believe that while the emission at 256 nm is a clear photoemission, the emission at longer wavelengths is likely the field emission caused by intense electric fields of the laser.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 2130
EP  - 2133
KW  - laser
KW  - electron
KW  - cathode
KW  - photon
KW  - experiment
DA  - 2019/06
PY  - 2019
SN  - 978-3-95450-208-0
DO  - DOI: 10.18429/JACoW-IPAC2019-TUPTS089
UR  - http://jacow.org/ipac2019/papers/tupts089.pdf
ER  - 

TY  - CONF
AU  - Lutman, A.A.
AU  - Bane, K.L.F.
AU  - Ding, Y.
AU  - Emma, C.
AU  - Guetg, M.W.
AU  - Guo, G.
AU  - Hemsing, E.
AU  - Huang, Z.
AU  - Krzywiński, J.
AU  - MacArthur, J.P.
AU  - Marcus, G.
AU  - Marinelli, A.
AU  - Maxwell, T.J.
AU  - Novokhatski, A.
ED  - Boland, Mark
ED  - Tanaka, Hitoshi
ED  - Button, David
ED  - Dowd, Rohan
ED  - Schaa, Volker RW
ED  - Tan, Eugene
TI  - XFEL Operational Flexibility due to the Dechirper System
J2  - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019
CY  - Melbourne, Australia
T2  - International Particle Accelerator Conference
T3  - 10
LA  - english
AB  - The RadiaBeam/SLAC dechirper was installed to demonstrate the concept of using wakefields from a corrugated structure to change the energy profile along an electron bunch. Since installation, the system has allowed a large number of additional XFEL operating modes including fresh-slice two-color or three color operation, fresh-slice seeding, passive streaking, etc. This talk will discuss the results from using the dechirper system and possible implementation issues related to the high-rate LCLS-II.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 2219
EP  - 2223
KW  - electron
KW  - undulator
KW  - FEL
KW  - controls
KW  - laser
DA  - 2019/06
PY  - 2019
SN  - 978-3-95450-208-0
DO  - DOI: 10.18429/JACoW-IPAC2019-WEXPLM1
UR  - http://jacow.org/ipac2019/papers/wexplm1.pdf
ER  -