CLASSE, Ithaca, New York, USA
We report on the status of emittance tuning techniques at the CESR Test Accelerator CesrTA. The CesrTA experimental program requires the capability to operate in a variety of machine lattices with the smallest possible emittance. We have attempted to minimize the turn-around time of our low emittance tuning procedure. We utilize high bandwidth BPM electronics for fast, precision measurements of orbit, betatron phase, transverse coupling, and dispersion. Turn by turn data is used to measure BPM button electrode gains to a under a percent. Gain-corrected coupling data is utilized to determine BPM tilts to 10mrad, allowing for measurement of vertical dispersion at the level of 10mm. Measurement and analysis of the data for characterizing BPM response takes 5 minutes. Beam based measurement of machine functions, data analysis, and implementing corrections in the machine takes another 5 minutes. An x-ray beam size monitor provides a real time check on the effectiveness of the procedure. A typical correction results in an emittance less than 20pm at 2.1GeV in 1-2 iterations. Sub 15pm has been achieved with adjustment of closed coupling/vertical dispersion bumps and betatron tunes.
CLASSE, Ithaca, New York, USA
Cornell University, Ithaca, New York, USA
Electron cloud buildup is a primary concern for the performance of the damping rings under development for the International Linear Collider. We have performed synchrotron radiation profile calculations for the 6.4-km DC04 and 3.2-km DSB3 lattice designs using the SYNRAD utility in the Bmad accelerator software library. These results are then used to supply input parameters to the electron cloud modeling package ECLOUD. Contributions to coherent tune shifts from the field-free sections and from the dipole and quadrupole magnets have been calculated, as well as the effect of installing solenoid windings in the field-free regions. For each element type, SYNRAD provides ring occupancy, average beam sizes, beta function values, and beta-weighted photon rates for the coherent tune shift calculation. An approximation to the antechamber design has been implemented in ECLOUD as well, moving the photoelectron source point to the edges of the antechamber entrance and removing cloud particles which enter the antechamber.
CLASSE, Ithaca, New York, USA
Cornell University, Ithaca, New York, USA
Energy Recovery Linacs (ERLs) are proposed as drivers for hard X-ray sources because of their ability to produce electron bunches with small, flexible cross sections and short lengths at high repetition rates. The advantages of ERL lightsources will be explained, and the status of plans for such facilities will be described. In particular, Cornell University plans to build an ERL light source, and the preparatory research for its construction will be discussed. This will include the prototype injector for high current CW ultra-low emittance beams, superconducting CW technology, the transport of low emittance beams, halo formation from intrabeam scattering, the mitigation of ion effects, the suppression of instabilities, and front to end simulations. Several of these topics could become important for other modern light source projects, such as SASE FELs, HGHG FELs, and XFELOs.
