Electron Cooling System Research Articles

Strategy of intense ion beam accumulation by use of charge exchange injection

Accumulation of ions in a storage ring using charge exchange injection gives the possibility of storing the ion beam with parameters applicable to plasma experiments. Beam quality on the target can be defined by the factor of beam quality K b=1.5 Pa, where P is specific power, and a is beam radius. A simple formula, which allows one to estimate the value of K b for arbitrary accelerator parameters, is derived. This formula shows that in the absence of an electron cooling system (ECS) the main limitations appear due to intra beam scattering, increasing momentum spread of the stored beam. A more accurate analysis for ITEP-TWAC project is made by use of Monte-Carlo code. Four different storage scenarios are considered: fast scenarios with high intensity of injected beam and comparatively short accumulation time (10–20 injection cycles); slow scenarios with long accumulation time (100–200 injected cycles) (for both cases options with and without ECS have been considered). For all options, central injection scheme is used, where charge exchange target coincides with the center of the coasting beam. By optimization of the factor K b the optimal parameters (number of injections, intensity, emittance, momentum spread) have been calculated for each scenario.

Cooler synchrotron COSY

COSY Jülich is a cooler synchrotron and storage ring delivering high precision beams with at present up to 5·10 10 protons with momenta between 600 MeV/c and 3.3 GeV/c for medium energy physics. Two cooling systems are used to accomplish this goal. An electron-cooling system that reaches up to a momentum of 645 MeV/c and a stochastic cooling system that covers the upper momentum range from 1500 to 3300 MeV/c. Since its inauguration in April 1993 substantial progress in developing beams for internal and external experiments has been achieved and the physics program is now running. At the beginning of 1996 a polarized proton beam could be successfully accelerated up to 820 MeV/c for the first time.

Cooler synchrotron COSY — Performance and perspectives

COSY is a cooler synchrotron and storage ring delivering protons with momenta between 300 MeV/c and 3300 GeV/c for experiments in medium energy physics. It contains two cooling systems to shrink the beam phase space. An electron-cooling system reaches up to a momentum of 600 MeV/c and is complemented by a stochastic cooling system that covers the upper range from 1500 to 3300 MeV/c. Beam extraction is accomplished by the conventional resonant extraction mechanism as well as with the stochastic extraction method. Proton beams are being delivered routinely to three internal and three external experimental areas.

Attainment of space-charge dominated beams in a synchrotron.

For a given rf cavity voltage, there is a maximum attainable peak current in an ion storage ring. This occurs when the electric field from the beam space charge is balanced by the field from the rf cavity. In this limit, the linear charge density distribution is parabolic and incoherent synchrotron motion is suppressed. The beam energy spread cannot be determined from the bunch length which depends only on the beam current and rf voltage. This has been observed using the high energy electron-cooling system at the Indiana University Cyclotron Facility.