Speaker: Yi-Nong Rao
Abstract: Utilizing dedicated cyclotrons to produce medical isotopes is an arising technology in hospitals across Canada. We’ve proposed to design an innovative H_2^+ superconducting cyclotron TR100+ for the production of commercially valuable radioisotopes. This
project will be aiming at proton energy of 70−150 MeV and proton current of ∼800 μA, since (i) cyclotron in this energy range is not developed world-wide; (ii) in this energy range numerous highly interested and increasingly demanded radio-nuclides can be produced, e.g. Sr-82 and Ac-225. Our machine will be designed to accelerate H_2^+, by injection from external ion source and extraction by stripping. This will allow to extract
proton beam of variable energies with very high extraction efficiency, thus allow to reduce activation caused by beam losses. The basic parameters and some simulation studies of our machine will be presented in this talk.
4 replies on “Design of An Innovative Superconducting Cyclotron for Commercial Isotopes Production”
Very good project. I have two questions:
As the central region is much smaller, it should be careful to deduce the intensity limit of TR100 from the TR30.
Will beam loss bring trouble to the superconducting system?
Thanks for your comment. Here is my answer to your questions:
1. We would like to keep exactly identical between TR100+ and TR30 over the first a few turns. This is one of our basic considerations. So, one can simply scale the injection energy, dee voltage and rf frequency for the TR100+ in terms of the ratio of B_0 of these 2 machines. The measurements for the TR30 demonstrated 1.0 mA beam current accepted under 5 mA
injected dc beam. Based on this, we estimate a 0.8mA proton intensity goal for the TR100+. Another possible way to mitigate the space charge effect in the central region would be to increase the injection voltage.
2. Right. Beam loss is one of the major concerns, particularly for the high intensity superconducting machine. One might consider to apply local field bump using a iron piece or permanent magnet to allow the dissociation of H_2^+ into proton at proper azimuths instead of all along the path, and bring the protons out of the acceleration chamber and dump at proper position in the vacuum chamber.
I see that two main limitations are the dissociation of the low bounded vibrational states and the space charge effect at the central region.
I like to suggest some way to mitigate these problems.
About the dissociation of vibrational states my solution is to apply extra magnetic field bumper at proper azimutal position on the hills with an angular extension of about 1 degree or less. The beam bump can be produced by a iron piece or by permanent magnet. The azimutal position of the bump depend by the orbit radius (or by beam energy).
With this trick you produce the dissociation of H2+ into proton at a proper azimuth position and not all along the path. If you choose the proper azimut angle for each radius you are able to send the proton beam out of the acceleration chamber and to intercept in a proper beam dump placed at the proper position in the vacuum chamber.
To mitigate the space charge effect at the central region, please increase the injection voltage. If you double the injection energy you should be able to increase the injected current at least of a factor 2.
Hi Luciano,
Thanks for your suggestions.
1. The field bumps must be symmetrically placed in azimuthal direction. Right? Otherwise, they would introduce unwanted harmonics.
2. The space charge limit has been studied for decades, but TR30’s routine operation even can’t reach that limit. Instead, it’s limited, in reality, by the erosion of the electrodes in the first turn. Almost 1/3 of the electrode (copper) is eroded and even missing after a few months operation, and this happens periodically. This is the situation of TR30, which was deemed to be highly optimized in the design of centre region in terms of that set of parameters.
Maybe the copper is not a good choice for the electrode?
Doubling the injection energy would certainly raise the s.c. limit. With an injection energy of say > 60 keV, what would be the implication to the ion source design?