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TY - CONF AU - Kleeven, W.J.G.M. AU - Forton, E. ED - Conradie, Lowry ED - De Villiers, John Garrett ED - Schaa, Volker RW TI - An Improved Concept for Self-Extraction Cyclotrons J2 - Proc. of Cyclotrons2019, Cape Town, South Africa, 23-27 September 2019 CY - Cape Town, South Africa T2 - International Conference on Cyclotrons and their Applications T3 - 22 LA - english AB - A study is made for an improved concept of self-extraction in low and medium energy cyclotrons to be used for production of medical isotopes. The prototype of the self-extracting cyclotron was realized around the year 2001*. From this machine, currents higher than 1 mA were extracted and transported to a Pd-10³ production target. However, at the higher intensities, the extraction efficiency was dropping to about 70-75%, and the extracted emittance was rather poor, leading to additional losses in the beamline. Several improvements of the original concept are proposed: i) the beam coherent oscillation (as needed for good extraction) is no longer generated with harmonic coils, but is obtained from a significant off-centring of the ion source, ii) the cyclotron magnet has perfect 2-fold symmetry, allowing the placement of two internal sources and dual extraction on two opposite hill sectors, iii) a substantial improvement of the magnetic profile of the hill sectors. Simulations show an extraction efficiency up to almost 95% and emittances at least a factor 3 lower as compared to the original design. The new magnetic design is shown, and results of beam simulation are discussed. PB - JACoW Publishing CP - Geneva, Switzerland SP - 330 EP - 333 KW - extraction KW - cyclotron KW - ion-source KW - simulation KW - site DA - 2020/06 PY - 2020 SN - 978-3-95450-205-9 DO - doi:10.18429/JACoW-Cyclotrons2019-THD03 UR - http://jacow.org/cyclotrons2019/papers/thd03.pdf ER -