Report of the working group on plasma phenomena in beams

This working group was charged with reviewing the general area of plasma phenomena in beams. The group reviewed our present understanding and discussed critical issues for a wide variety of topics, including longitudinal and transverse wakefield instabilities in high intensity rings, numerical computation of wakes at short scale length, ion instabilities, wakefields and emittance growth from coherent synchrotron radiation, the nature of self-amplified spontaneous emission (SASE), soliton theory and its role in beam physics, the control of transverse instabilities by feedback or by temporal variation of ring parameters, and the use of plasma concepts in beam dynamics, particularly applications of beam echo measurements.