The status of stochastic cooling and developments over the years are reviewed with reference to much of the original work. Both theoretical and technological subjects are considered.

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Stochastic cooling overview

Beam Dynamics Newsletter

As circular accelerators move towards larger numbers of bunches and higher beam currents, the task of diagnosing and curing coupled-bunch instabilities becomes ever harder. This paper describes the use of phase space tracking, i.e. reconstruction of bunch phase space trajectories, as a comprehensive instability diagnostic. A new instability cure is also presented, based on recent insights into the dynamics of unevenly-filled rings. Data is shown from PEP-II and the ALS, where "optimally shaped" uneven fills have yielded significant increases in instability thresholds.

New diagnostics and cures for coupled-bunch instabilities

Dielectric-loaded power extraction is a method for the generation of high-power radio frequency (rf) waves under development for future particle accelerators. In this method, a high-charge electron beam drives a wakefield in a dielectric-loaded waveguide (the decelerator) and an rf output coupler extracts the rf power into an external waveguide. We report on the experimental demonstration of a 7.8 GHz dielectricloaded power extractor at the Argonne Wakefield Accelerator facility. We have generated more than 30 MW of rf power with a pulse length of approximately 1.7 ns by passing a single 66 nC electron bunch through the power extractor. We have also used a train of 4 electron bunches to show a clear signature of field superposition. Test results are in good agreement with predictions.

Design and testing of a 7.8 GHz power extractor using a cylindrical dielectric-loaded waveguide

3. Measurement Techniques ........................... 5 3.1 Equipment ............................... 5 3.2 Errors ................................. 5 4. Performance of Twelve Colliders ....................... 6 4.1 Luminosity versus Current ....................... 9 4.2 Core Enlargement ........................... 9 4.3 Large Amplitude Particles ...................... ‘10 4.4 Tune Shift Limits .......................... 13 4.5 Tune Choices ............................. 19 4.6 Performance Predictions ....................... 19 5. Luminosity Improvements ......................... 20 5.1 Luminosity Limits .......................... 20 5.2 Aperture Limited Colliders ..................... 21 5.3 Current and Tune Shift Limited Colliders .............. 23 5.4 Current Limited Colliders ...................... 25 5.5 Geometric Approaches ......................... 25 5.6 Suppression of Non-Gaussian Beam Tails .............. 26 6. Limits of Vertical Beta Reduction ..................... 26 6.1 Geometrical Loss of Luminosity ................... 27 6.2 Tune Shift Limitations ........................ 27 6.3 Non-Gaussian Vertical Tail Growth ................. 29 6.4 Dynamic Aperture .......................... 29 6.5 Quadrupole Regulation ....................... 30 7. Conclusions ................................. 30 8. Acknowledgements ............................. 31

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W.S. Newman

Papers

Proceedings, 11th International Conference on High-Energy Accelerators, HEACC 1980