High Intensity Ion Beam Injection into the 88-inch Cyclotron

Low cross section experiments to produce super-heavy elements have increased the demand for high intensity heavy ion beams at energies of about 5 MeV/nucleon at the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. Therefore, efforts are underway to increase the overall ion beam transmission through the axial injection line and the cyclotron. The ion beam emittance has been measured for various ion masses and charge states. Beam transport simulations including space charge effects were performed for both the injection line and the ion source extraction. The relatively low nominal injection voltage of 10 kV was found to be the main factor for ion beam losses, because of beam blow up due to space charge forces at higher intensities. Consequently, experiments and simulations have been performed at higher injection energies, and it was demonstrated that the ion beams could still be centered in the cyclotron at these energies. Therefore, the new injector ion source VENUS and its ion beam transport system (currently under construction at the 88-Inch Cyclotron) are designed for extraction voltages up to 30 kV.