Studies on Hollow E-lens Operation and Beam Halo Removal
Explore the operational aspects and beam halo removal techniques using Hollow E-lens in high-energy particle accelerators. Detailed insights into beam scanning, new ideas for beam halo management, system status, lattice requirements, and APEX plan are discussed.
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Presentation Transcript
E-lens related beam studies Xiaofeng Gu, Wolfram Fischer, BNL Giulio Stancari, FNAL P. Hermes, D. Mirarchi, S. Redaelli, R. Bruce, CERN 1
Outline 1.Beam Halo Removal via Hollow E-lens. 2.New Ideas. 3.Status and Plan. 2
Radius Scan The hollow e-lens could be operated without significantly affecting the beam core or luminosity with the inner beam size of 4.3 . https://journals.aps.org/prab/pdf/10.1103/PhysRevAccelBeams.23.031001 6
New Idea for Beam Halo HEL is switched on for I turns and switched off for J turns. Depleted tail rate[%/s]: clear resonance visible for I+J = 24 Provided by: P. Hermes, D. Mirarchi, S. Redaelli 7
New Idea Single particle, not orbit Provided by: P. Hermes, D. Mirarchi, S. Redaelli 8
E-lens System Status Both blue and yellow e-lens were not operated for several years. Blue e-lens has a Gaussian profile cathode, while Yellow e-lens is hollow profile beam. Need to check all systems: power supplies, controls, instrumentation at the beginning of the run Need to check the feasibility of the I On J Off pattern (timing) Need to find the I and J for RHIC lattice 9
APEX Plan 1. With current configuration, BTF measurements at 255 GeV with blue gaussian e-lens. 2 SHIFTS APEX, probably best in conjunction with the hollow lens experiments 2. Hollow beam removal rate study with yellow e-lens. 2~3 SHIFTS APEX IF it is possible: Once complete, and time permitting, we switch the Yellow cathode to a Gaussian also (7.5 cm radius)and re-establish head-on beam-beam compensation in preparation for Run-24. Could be done with 12 or 28 bunches of the highest available bunch intensity, and possibly with the transverse damper. 2-4 SHIFTS APEX 3. 11
APEX Plan (hollow beam detail) [Experiment 0 - Collimator position calibration] Extinction scan of low-intensity fill to calibrate collimator position with respect to beam orbit. [Experiment 1 - Periodic excitation patterns] (Verify capabilities of RHIC e-lens triggers: I turns on, J turns off. Is it possible to have multiple patterns at the same time to do experiments simultaneously? Lattice to Pascal for predictions.) Fresh fill. Activate excitation pattern with e-lens at about 4 sigma for a few minutes. A few different e-lens current settings in sequence. Do partial collimator scan (3-5 sigma, for instance) at the end. Ne Giulio Stancari <stancari@fnal.gov> w fill with different excitation pattern. Try 2 or 3 patterns (weak and strong depletion rates, based on predictions). [Experiment 2 - Effect of nonlinearities] (Formulate predictions beforehand, if possible.) Fresh fill. E-lens in DC mode at about 4 sigma. Octupoles at one setting. A few different e-lens current settings in sequence. End with partial collimator scan. New fill with different octupole settings. Try 2 or 3 octupole settings. 12
Thank you. 13
