TUB1TU01
JLab, Newport News, Virginia, USA
JLab, Newport News, Virginia, USA
ODU, Norfolk, Virginia, USA
In the JLab Electron Ion Collider (JLEIC) project the traditional electron cooling technique is used to reduce the ion beam emittance at the booster ring, and to compensate the intrabeam scattering effect and maintain the ion beam emittance during the collision at the collider ring. Different with other electron coolers using DC electron beam, the proposed electron cooler at the JLEIC ion collider ring uses high energy bunched electron beam, provided by an ERL. In this paper, we report some recent simulation study on how the electron cooling rate will be affected by the bunched electron beam properties, such as the correlation between the longitudinal position and momentum, the bunch size, and the Larmor emittance.
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
JLab, Newport News, Virginia, USA
For a high-brightness electron beam with low energy and high bunch charge traversing a recirculation beamline, coherent synchrotron radiation and space charge effect may result in the microbunching instability (MBI). Both tracking simulation and Vlasov analysis for an early design of Circulator Cooler Ring* for the Jefferson Lab Electron Ion Collider reveal significant MBI. It is envisioned these could be substantially suppressed by using a magnetized beam. In this work, we extend the existing Vlasov analysis, originally developed for a non-magnetized beam, to the description of transport of a magnetized beam including relevant collective effects. The new formulation will be further employed to confirm prediction of microbunching suppression for a magnetized beam transport in a recirculating machine design.
*Ya. Derbenev and Y. Zhang, COOL'09 (FRM2MCCO01)
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
JLab, Newport News, Virginia, USA
Microbunching instability (MBI) has been a challenging issue in high-brightness electron beam transport for modern accelerators. The existing Vlasov analysis of MBI is based on single-pass configuration*. For multi-pass recirculation or a long beamline, the intuitive argument of quantifying MBI, by successive multiplication of MBI gains, was found to underestimate the effect**. More thorough analyses based on concatenation of gain matrices aimed to combine both density and energy modulations for a general beamline**. Yet, quantification still focuses on characterizing longitudinal phase space; microbunching residing in (x,z) or (x',z) was observed in particle tracking simulation. Inclusion of such cross-plane microbunching structures in Vlasov analysis shall be a crucial step to systematically characterize MBI for a beamline complex in terms of concatenating individual beamline segments. We derived a semi-analytical formulation to include the microbunching structures in longitudinal and transverse phase spaces. Having numerically implemented the generalized formulae, an example lattice*** is studied and reasonable agreement achieved when compared with particle tracking simulation.
* Heifets et al., PRSTAB 5, 064401 (2002), Huang and Kim, PRSTAB 5, 074401 (2002), and Vneturini, PRSTAB 10, 104401 (2007)
** Tsai et al., IPAC'16 (TUPOR020)
*** Di Mitri, PRSTAB 17, 074401 (2014)
