Extraction by Stripping of Heavy Ion Beams from AVF Cyclotrons

Transcription

1 Slide 1 ECPM 2007 Extraction by Stripping of Heavy Ion Beams from AVF Cyclotrons G.G. Gulbekyan,, O.N. Borisov,, V.I. Kazacha,, D. Solivaijs Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research

2 Slide 2 The method of heavy ion beam extraction from AVF cyclotrons was suggested by G.N. Vialov, G.N. Flerov and Yu.Ts. Oganessian in 1964 [1] Academician of the RAS Academician of the RAS G.N. Flerov Yu.Ts. Oganessian [1] G.N. Vialov, G.N. Flerov, Y.Ts. Oganessian.. JINR Preprint 1884, Dubna, 1964

3 Slide 3 The method of heavy ion beam extraction from AVF cyclotrons suggested by G.N. Vialov, G.N. Flerov and Yu. Oganesyan in 1964

4 Slide 4 0,0-0,5 U Kr 8+ ; W=4.25 MeV/amu -1,0-1,5 Y ( m ) -2,0-2,5-3,0 Z 2 =27 Z 2 =26 Z 2 =25 Z 2 =24-3,5-3,5-3,0-2,5-2,0-1,5-1,0-0,5 0,0 X ( m ) Two-turn extraction from U400

5 Slide 5 Ion 7 Li 12 C 40 Ar 48 Ca 136 Xe Z 1 MeV Z 2 Zamu W Mev/amu 8,6 16,6 5,1 5,2 5,5 U400 some parameters of accelerated and extracted ion beams Z Z 2 /Z ,6 2,8 EXT eff % 100% 95% 50% 45% 25% I target pµa ,5 0,1 EXT eff I target - extraction efficiency - the extracted beam intensity

6 Slide 6 2,0 1,5 U-400M Y (m) 1,0 0,5 0, Q = 0 o -0,5-1,0-1,5-2,0-2,5 Θ = 105 o R = 2.85 m Q = 90 o -3,0-2,0-1,5-1,0-0,5 0,0 0,5 1,0 1,5 2,0 2,5 X (m) The reference particle trajectories of the ions extracted from U400M cyclotron by method 2

7 Slide 7 U400M some parameters of accelerated and extracted ion beams Ion W Mev/amu Z 1 Z 2 Z 2 /Z 1 EXT eff % I target pµa 7 Li , B , N , Ne , Ar , EXT eff I target - extraction efficiency - extracted beam intensity

8 Slide 8 2,0 U - 400M : Extraction by stripping ( A/Z = 9.5 ) 1,5 1,0 0,5 0,0 Θ = 0 o Θ = 180 o Y [ m ] -0,5-1,0-1,5-2,0 Z 2 /Z 1 = ,5 Θ=43.2 o R=300 cm -3,0 Θ = 90 o -3,5-3,0-2,5-2,0-1,5-1,0-0,5 0,0 0,5 1,0 1,5 2,0 X [ m ] The trajectories of the low energy ion beams extracted from U400M cyclotron by method 1

9 Slide 9 0,0 Θ=180 o 72 MeV Θ = 0 o -0,5 DC Z ex /Z ac =2.0-1,0 Y ( m ) -1,5-2,0-2,5 matching point R=2.8 m ; Θ=237.5 o -3,0 Θ = 270 o -3,5-2,5-2,0-1,5-1,0-0,5 0,0 0,5 1,0 1,5 X ( m ) Reference trajectories of the ions extracted from DC-72 cyclotron

10 Slide 10 STRIPPING FOILS Be, C, Al, Al 2 O 3, mailar For every accelerated ion there is so called equilibrium thickness of the foil at which increasing the charge distribution does not change but the angle scattering keeps on growing [ ] [ ] µ g cm 2 30 W 0,6 MeV amu

11 Slide 11 <Z i >/Z p, arb. units 1,0 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 B Ne Ar U Xe Kr 0,0 0, W, MeV/amu Dependence of the ion stripping degree on the ion energy

12 Slide 12 Dependence of the maximum efficiency of a single charge extraction by stripping versus the ion energy

13 Slide 13 σ θ, mrad B U W, MeV/amu Dependence of the scattering angles for B and U in the carbon foils having the equilibrium thickness

14 Slide 14 σ E /E 0, arb. units 1E-3 1E-4 B Ar Kr U 1E-5 0, W, MeV/amu Additional energy spread of the extracted ion beam

15 Slide 15 RADIATION DAMAGE Estimation of the foil lifetime T [hours] ( 3 6) 10 3 Zp 2 MeV W amu j pµ A cm 2 Z p - ion element number, W - ion energy, J - beam current density.

16 Slide 16 The stripping foil before using Probe head of U400 cyclotron with the stripping foil

17 Slide 17 Losses, Watt/pµA ,1 U Xe Kr Ar B 0, W, Mev/amu Power losses of the ion beam in the stripping foil

18 Slide 18 Thermal evolution of the carbon foil thickness

19 Slide 19 Thermal evolution of the carbon foil with thickness 1 µm by the beam having Gaussian distribution

20 Slide 20 6-sector cyclotron model

21 Slide 21 Certainly this information is only an indication that there is a possibility of the beam extraction by stripping especially near the region borders. Simulation of the trajectories and envelopes must be carried out in real magnetic fields N3, M1, = 1.01, = 0;±45º A N3, M2, = 1.01, = 0;±45º B Simulation results for borders of the admissible stripping coefficient (1/4) 2

22 Slide 22 N4, M1, = 1.01, = 0; ±45º C N4, M2, = 1,01, = ±45º D Simulation results for borders of the admissible stripping coefficient (2/4) 3

23 Slide 23 N4, M1, = 1,43, = ±45º E N4, M2, = 1,43, = ±45º F Simulation results for borders of the admissible stripping coefficient (3/4) 4

24 Slide 24 N6, M1, = 1,43, = ±45º G N6, M2, = 1.43, = ±45º H Simulation results for borders of the admissible stripping coefficient (4/4)

25 Slide C5+ => C 6+ ; W=400 MeV/n Y [ m ] X [ m ] Extraction trajectories by stripping (N6, =1.43, =+45, flatter=1)

26 Slide 26 CONCLUSION qextraction of the heavy ion beams by stripping from AVF cyclotrons is convenient in realization. The extraction efficiency of sum of the charges after stripping is about 100% and for a single charge it is from 20 up to 100% in dependence of the ion type and energy. qthe stripping foil weekly affects on the extracting beam quality. The foil lifetime can be well estimated by the radiation damage. Under high power losses (> 150 W/cm 2 ) sublimation of carbon defines the foil lifetime. qthe magnetic structure type of AVF cyclotron strongly affects on the possibility of the ion extraction by stripping. It is possible to extract by stripping the ion beams , , with the energy 400 MeV/amu from 4 and 6-sector AVF cyclotrons

27 Slide 27 ECPM 2007 Extraction by Stripping of Heavy Ion Beams from AVF Cyclotrons THANKS FOR YOUR ATTENTION G.G. Gulbekyan,, O.N. Borisov,, V.I. Kazacha,, D. Solivaijs Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research