PROGRESS ON THE DESIGN STUDIES OF THE 300AMeV SUPERCONDUCTING CYCLOTRON

Transcription

1 PROGRESS ON THE DESIGN STUDIES OF THE 300AMeV SUPERCONDUCTING CYCLOTRON Mario Maggiore on behalf of R&D Accelerator Group Laboratori Nazionali del Sud Catania, Italy CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

2 Contents INTRODUCTION INJECTION STUDY BEAM DYNAMIC EXTRACTION LAYOUT CAVITY DESIGN STRUCTURAL & MECHANICAL ANALYSIS SUMMARY CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

3 The 300 AMeV choice At the end of 2005 the SCENT project has been completed. The preliminary studies of a superconducting cyclotron able to accelerate ions with mass to charge ratio of 0,5 up to energy of 250 AMeV for hadrotherapy, were carried out by the Accelerator R&D group of LNS. In March 2006, we have investigated the possibility to increase the extraction energy of the carbon ions up to 300 AMeV, increasing the main magnetic field, but keeping unchanged the main parameters of the machine. Moreover, we tried to extract the proton beam by the stripping process at the energy of 250 AMeV. CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

4 Why 300AMeV is better than 250AMeV (carbon ions)? C 250 AMeV C 300 AMeV 174 mm depth ~ 75 % of targets Courtesy of HIMAC CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

5 Main parameters Parameters Particles Injection energy Extraction Energy K bending Number of sectors Extraction radius Hill gap Main size Weight Coils Nominal current Current density Number of cavities RF cav. frequency RF power Extraction Systems Values H 2 +, 12 C AKeV 12 C 300 AMeV 260 AMeV 1200 MeV cm 50 mm 5 m x 3 m 350 tons A pair of SC 950 amp 45 amp/mm MHz, 4 th harmonic 50 kw per cavity Electrostatic deflectors in the hills Stripping process CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

6 Coils parameters Coil Parameters Size Current density Inner Radius Distance from the M.P. Energy Stored Nominal Current (I) Total current (NI) Max Magnetic field Axial Force Average Hoop Stress (peak) 150x210 mm 2 45 amp/mm mm 70 mm 35 MJ amp 1.42 Mamp 4.4 tesla MN 156 (284) MPa Conservative Design CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

7 Injection System E inj =25 AKeV DV inflect = 14 KV gap inflect = 6 mm E inflect = 23KV/cm CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

8 Central region design B (gauss) E inj =25 AKeV radius (cm) B o = 3.18 tesla V dee = 70 KV E gap = 100 KV/cm CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

9 Magnetic properties Working in 4 th harmonic Very accurate Isochronism CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

10 Resonance s troubles Working diagram (Carbon ion) The preliminary magnetic model did not show any crossing of dangerous resonances. But the need to get an accurate isochronous field to optimize the beam dynamic produced troubles injection CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

11 Resonances crossing Refined Model Many turns around the dangerous resonance The goal was to optimize the magnetic field to cross the resonance in few turns CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

12 Carbon to H 2+ switch 12 C 6+ H C 6+ H 2 + It need to change the magnetic field CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

13 Solution proposed TRIM RODS Additional RT coil CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

14 Extraction layout and beam envelopes C 300AMeV Radial env. Vertical env. 12 C 6+ ED1 [cm] 1 0,8 0,6 0,4 0,2 0-0,2-0,4-0,6-0,8-1 ED1 ED [degree] 260 MeV MC ED2 1,25 0,75 [cm] 0,25-0,25-0,75 protons -1, [Degree CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

15 Cavity design Number of cavities Frequency Harmonic number Total height MAIN PARAMETERS Gap width range Quality factor Q0 Voltage average min & max Number of stems Max electric field RF Power Coupling system 4 98 MHz 4 80 cm cm KV 3 10 MV/m 50 kw/cavity Inductive loop CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

16 Deflectors in the valleys? N stem = 4 Height= 84 cm Length =230 cm Width = 43 Deflector housing and an azimuthally wider valley produce a strong increase of Dee s capacitance f o = MHz Q= 9200 <V> max =100KV R sh = K P loss =68 kw/cav CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

17 Iron Yoke subdivision ELEMENT WEIGHT Upper pole caps 92 tons Lower pole caps 20 tons ring 62 tons Total weight of the half yoke 174 tons CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

18 Stress Analysis Applied Load= 3000 tons Max Mech. Stress = 3,8 kg/mm 2 (yield strength= 19 kg/mm 2 ) Max Displacement = 0,298 mm CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

19 Summary The studies done so far show that the energy range of 300 AMeV for Carbon ions, can be achieved keeping the main structural parameters of the SCENT machine and the feasibility study is almost completed. We demonstrated that single turn extraction is possible by stripping the proton beams at the energy of 260 MeV. Despite the high magnetic field and the low injection energy, the central region was designed to 70KV with four DEEs. The tuning of the magnetic field (CARBON to H 2 + switch) is still under study, even if we are confident on the proposed solution. CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct

20 GRAZIE! CYCLOTRONS 2007, Giardini Naxos, Italy, 30 Sept-5 Oct