Hadron Accelerator improvement toward high intensity and hi8gh brightness beams

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1. Instability analysis including the electron cloud effect was performed using the KEK-PS and J-PARC parameters.2. A kicker parameter was studied for the J-PARC ring.3. Stability analysis of the head-tail instabilities with feedback dampers, using two-particle model, and the J-PARC parameters.4. Experiments at the KEK-12 GeV-PS Main Ring at the injection energy (500 MeV)(1) Experiment of feedback damping with one monitor and one kicker.Succeeded in damping a head-tail instability ( mode 0, growth-rate ~30 ms) using an analog circuit.(2) A digital signal processing (fast processing with a Field Programmable Gate Array) and an analog signal processing were applied and compared. Similar damping times were achieved.(3) Stability was analyzed with one-particle model.(4) Experiment of feedback damping with two monitors and one kicker with a digital signal processingThe instability was stabilized. But strong damping effect could not be studied because the RF amplifier was saturated with a large remaining COD (closed orbit distortion) signal. Elimination of the COD component is the next subject.5. Analysis of two-monitor and two-kicker configuration(1) Exact solution was obtained for the stability with two monitors and one kicker, using one particle model. The solution for the fast damping regime is far different from the approximate solution for the small damping regime, and realizes one-or two-turn damping if appropriate parameters are chosen. Issues are (a) oscillation amplitude increases over the initial amplitude for a moment; (b) the stability region is restricted.(2) The numerical solution was obtained for the stability with two monitors and two kickers, using one particle model. Both above issues are resolved in this case. Analysis with the two-particle model and multi particle simulation is the next subject.