Evgeny Syresin

The variable current gun: the parameter tests and the results of the first electron cooling experiments at LEAR

Abstract The electron cooling time (or equivalently the cooling force) is inversely proportional to the electron beam current Ib, aimed to cool hot low-energy ions [1–3]. On the other hand, highly cooled ions tend to become unstable. This implies that once the ion beam upper density limit is attained, the electron current intensity has to be reduced to a level which prevents the ion beam instability and maintains low emittances. An adiabatic-type gun [4–6] has been constructed, which provides low-temperature electrons of large, but variable densities. The electron current density is adjusted through the voltage control, Ug, of a so-called grid electrode. Its main drawback is the storage of secondary electrons when the grid potential is larger than the anode potential, thus inducing a reduction of the nominal electron current intensity. A detailed analysis of the storage process is presented, and the way to cure this drawback is explained. Finally, experimental results are given.

The parameters of the secondary electrons in the electron cooling system

Abstract The secondary electrons in an electron cooling system determine the current losses [1]. Their parameters depend on the collector efficiency. In this paper the behaviour of the secondary electrons in the LEAR electron cooler with S-shaped bending toroid magnets is examined. The second problem which takes place with secondary electrons is related to the generation of neutralised electron beams in an electron cooling system [2]. The generation of very dense neutralised beams is restricted by the beam-drift instability. This is a convective instability appearing in stationary conditions due to the feedback created by secondary electrons.

S-LSR Cooler Ring Development at Kyoto University

A compact ion cooler ring, S‐LSR is under construction in Kyoto University. One of the subjects of S‐LSR is a realization of the crystalline beams using the electron beam and the laser cooling. The ring is designed to be satisfied several required conditions for the beam ordering, such as a small betatron phase advance, a small magnetic error and a precise magnet alignment. The design phase advance per a period is less than 127 degree. The calculated closed orbit distortion and the stopband is less than 1 mm and 0.001 without correction, respectively.

NICA Collider Lattice Optimization

The Nuclotron-based Ion Collider fAcility (NICA) [1] is a new accelerator complex being constructed at JINR. It is aimed to collider experiments with ions and protons and has to provide the ion-ion (Au +79 ) and ion-proton collision in the energy range of 14.5 GeV/u and also polarized proton-proton (512.6 GeV) and deuterondeuteron (25.8 GeV/u) collisions. Two collider rings are designed and optimized to achieve the required luminosity at two interaction points (IP). Taking into account space charge effects of the intense ion beam the application of electron beam or stochastic cooling methods were proposed to provide beam or luminosity lifetime. This paper is considering one of the most challenging problems of accelerator physics that is finding the dynamic aperture (DA) of the collider ring.