Present state of electron cooling studies

The experiment results on electron cooling at the NAP-M proton storage with a zero gradient and wedge focusing are given. To elucidate the contribution of remote collisions into the fast quenching effect the decrement dependences of transverse oscillations and longitudinal component of friction force on the Larmor rotation velocities and velocity variations of the Larmor disks were measured. The measurements showed the equality of damping decrements of radial and vertical oscillations. The effect of relative longitudinal proton and electron velocities on damping decrement was studied by 200 Hz modulation of electron beam energy. At the longitudinal velocity modulation amplitude of 3.6x10-4 Vsub(3) (Vsub(s) - mean electron velocity) the decrement value reduces by one-half. The damping decrement depends on the transverse velocities of the Larmor disk centers to a more degree than on a rotation velocity. At 10-3 Vsub(s) transverse proton velocities the size of a proton beam coincides with the electron beam size and equals 10 mm. The proton beam energy variation depends linearly on a proton current and equals 2.9x10-6 at 5 μA and 2.6x10-5 at 40 μA