Several Topics in Recent Accelerator Studies Weiren Chou Fermilab June 10, 2003

Several Topics in Recent Accelerator Studies Weiren Chou Fermilab June 10, 2003

Several Topics in Recent Accelerator Studies Weiren Chou Fermilab June 10, 2003

Sifry, David, Founder & CEO of Technorati has reference to this Academic Journal, PHwiki organized this Journal Several Topics in Recent Accelerator Studies Weiren Chou Fermilab June 10, 2003 Presentation to the Midwest Accelerator Physics Meeting June 10-11, 2003, ANL Outline (1) Booster modeling (2) Space charge (3) Barrier RF stacking Fermilab Accelerator Complex

Strayer University-North Dallas TX

This Particular University is Related to this Particular Journal

(1) Booster Modeling The dogleg effect (Sasha’s talk) The first 3 milliseconds Chromaticity modeling Model improvement Booster power supply experiments at E4R Booster Beam Loss (courtesy R. Webber) First 3 milliseconds in the Booster Logitudinal loss The measured Booster longitudinal acceptance is small: 0.15-0.2% The measured linac beam momentum spread is about 0.13% When the beam is bunched, the momentum spread increases to 0.3% This exceeds the acceptance in addition to results in loss Transverse loss The transverse acceptance is: A = {max N/}1/2 + Dmax p/p + c.o.d. The magnet good field region is about 1.2 inch For regular max in addition to Dmax, the maximum allowable N is about 16 But the doglegs blow up the lattice function in addition to reduce N to about 8 The incoming linac beam is 7 Space charge dilutes the emittance during the multiturn injection, resulting in loss.

First 3 milliseconds in the Booster (cont ) When beam energy goes up, the situation improves rapidly: Longitudinal: E/E 1/2 p/p = (1/2) E/E Transverse: Dogleg focusing strength: 1/f = 2/L 1/p2 Beam size due to adiabatic damping: = N/ Space charge effect 1/2 In the middle in addition to late stage of the cycle, other schemes will contribute to the beam loss (e.g., transition crossing, coupled bunch instability), but which is beyond this topic. Chromaticity Modeling = (lat) + (dogleg) + (mag sext) + (chrom sext) Goal: To have a spreadsheet relating the sextupole current to the machine chromaticity throughout the cycle The task is complicated by two factors: The dogleg effect, which perturbs the local lattice function in addition to has an energy dependence (calculable) The main magnets have large sextupole component, which comes from both the body part in addition to the end packs (need measurement) Chromaticity Calculation (x) (y) Bare lattice (Lat) -9.16679 -7.03638 Lat + dogleg -9.57427 -7.01265 Lat + body sext -23.55770 11.65977 Lat + body sext + dogleg -23.40371 11.00271 Lat + body sext + chrom sext + dogleg 0.04399 -0.18496 Lat + body sext + chrom sext (no dogleg) 3.67119 -11.11968 The doglegs’ direct contribution to the chromaticity is small. But their impact on the chromaticity is significant because of the big change of local in addition to D at the chromaticity sextupoles.

Field Measurement at E4R A mole used as long as dc field measurement Main Magnet Sextupole Component Two independent measurements: Field measurement at the E4R Chromaticity measurement at the Main Control Room The two teams did not talk to each other on purpose (a blind check) The results are found to be in good agreement at 400 MeV Work in progress as long as ac measurement Main Magnet Sextupole Measurements (cont ) F magnet D magnet Body only Body+ends Chrom meas. Body only Body+ends Chrom meas.

Model Improvement Trim quads 24 H, 24 V Weak, about 2% of the main quad strength But perturbations on beta function in addition to tune are big MAD output does not seem to match the observation Steering magnets Not in the model yet Alignment errors Model uses old data, needs updated ones Aperture scanning Need to be re-done Power Supply Experiments at E4R Motivation: To make the existing RF system capable to accelerate more particles Experiment 1: Reduce the repetition rate from 15 Hz to 12 Hz Experiment 2: Dual harmonic resonant (15 Hz + 12.5% 30 Hz) Purpose: To reduce the peak RF power by 25% Booster Cell with 2nd Harmonic (courtesy D. Wolff)

Dual Harmonic Current in addition to dI/dt (3 cases: dual 0%, 9%, 18%; courtesy D. Wolff) Current I dI/dt (2) Space Charge Simulation codes ESME (P. Lucas, J. MacLachlan) ORBIT (F. Ostiguy, W. Chou) Synergia (P. Spentzouris, J. Amundson) Tune footprint Emittance blowup during in addition to after the injection IPM (Ion Profile Monitor) measurement Code benchmarking Linac 805 MHz Microbunches (ESME, courtesy P. Lucas) One microbunch with p/p = 0.13% Multiturn injection

Tune Footprint (ORBIT, varying beam intensity) Laslett tuneshift: 0.3 Emittance Histogram (ORBIT) No space charge With space charge Emittance Percentage (%) Emittance Growth (ORBIT, 11-turn injection, varying beam intensity) No space charge Fast growth during injection Slow growth after injection Turn inj

IPM Measurement (raw data) 40 mA, 10-turn injection 20 mA, 10-turn injection 45 turns inj Fast growth Slow growth IPM Measurement (processed data, courtesy P. Spentzouris) November data December data inj Emittance Growth during Injection (varying space charge effects) Transverse sc only Transverse + Longitudinal Longitudinal sc only No space charge Turn

Sifry, David Sifry's Alerts Founder & CEO of Technorati

Space Charge Code Benchmarking (12th ICFA Mini-Workshop, April 2-4, 2003, Ox as long as d, Engl in addition to ) Data: CERN PS experiment on Montague resonance (2x – 2y = 0) Participants in this benchmarking: F. Jones (Accsim) A. Luccio (Orbit) J. Holmes, S. Cousineau (Orbit) A. Adelmann (GenTrackE) H. Qin (Best) I. Hofmann (Micromap) W. Chou, F. Ostiguy, P. Lucas (Orbit) J. Qiang, R. Ryne (IMPACT, ML/I) D. Johnson, F. Neri (Simpsons) tune diagram (betatron periods per turn without space charge) Comparison with simulation (Gaussian/coasting beam) – observed broader than in simulation

(3) Barrier RF Stacking Motivation: To overcome the Booster bottleneck problem in addition to double the proton intensity on the production target. Method: To stack two Booster bunches into one MI bucket by using a barrier RF system. This is possible because the Main Injector momentum acceptance (0.4 eV-s) is larger than the Booster bunch emittance (0.1 eV-s) Ng’s simulation Barrier RF system in addition to bench test Booster Energy Loss (courtesy R. Webber) Stacking Goals Goal as long as Run2 – To increase protons per second (pps) on the pbar target by 50% Baseline: 5e12 every 1.467 sec Goal: 2 x 5e12 every 2 sec Goal as long as NuMI – To increase pps on the NuMI target by 60% Baseline: 3e13 every 1.867 sec Goal: 2 x 3e13 every 2.333 sec


Sifry, David Founder & CEO of Technorati

Sifry, David is from United States and they belong to Sifry’s Alerts and they are from  San Francisco, United States got related to this Particular Journal. and Sifry, David deal with the subjects like Opinion/Commentary

Journal Ratings by Strayer University-North Dallas

This Particular Journal got reviewed and rated by Strayer University-North Dallas and short form of this particular Institution is TX and gave this Journal an Excellent Rating.