Some features of transverse instability of partly compensated proton beams

Transverse e-p instability in the proton rings could be damped by increase in beam density and the rate of secondary particles generation above a threshold level, corresponded a decrease of the unstable wavelength below a transverse beam size. In high current proton rings as LANSCE PSR is possible to reach this "island of stability" by fast, concentrated charge exchange injection without painting and enhanced generation of secondary plasma as it was demonstrated in small scale PSR at BINP. After damping of e-p instability has been accumulated a circulating proton beam with intensity, corresponding a tune shift Δν=0.85×6 in the ring with ν=0.85. Transverse instability of a bunched beam was damped by a simple feed back. Experimental observations of a transverse instability of proton beams in different accelerators and storage rings will be discussed