Progress in April December 2007 Schedule in Jan. March 2008

Transcription

1 A Report to the Advisory Committee of CNS The Accelerator Group Outline Upgrade of AVF Cyclotron Progress in April December 2007 Schedule in Jan. March 2008 Shigeru Kubono, Yukimitsu Ohshiro, Shin-ichi Watanabe. Syoichi Yamaka(CNS) Sergey B. Vorozhtsov, Alexey S. Vorozhtsov, Evegeny E. Perepelkin (JINR) Akira Goto, Masayuki Kase (RIKEN) Toshinori Mitsumoto (SHI), Kichiji Hatanaka(RCNP) 2008/4/4 1

2 Layout of AVF Cyclotron Cycro center HyperECR AVF Cyclotron Room E7 CRIB FC-F0 R ext =0.714m B max =1. 7 T Vrf = 50 kv h =2 F 0 =12~24MHz 2008/4/4 2

3 Specifications of RIKEN AVF K-value 78 MeV M/Q 2 Acc.Beam 14 N MeV/u Average Max.field 17.8 kg Extraction radius 714 mm Dee angle 83x2 Dees Voltage peak 50 kv RF frequency MHz RF power 2 x 50 kw Main coil power 214 kw (1200 A) Circular coil 8 pairs Harmonic coil 4 pairs Vacuum pump 1500 l/s TMP x l/s CRYO x l/s CRYO x1 Manufactured 1989 (upgraded 2006) 10GHz ECR HyperECR RRC, PA CRIB 2008/4/4 3

4 10 years over view HyperECR Improve SF ECR BT Charge breeder AVF Flat top High power RF Main & Trim coil Center region Improvements Beam line E7(CRIB) SF clean up PA Monitor DCCT Cluster Rf buncher VIS JSPS foundation Contribution to AVF upgrade Atomic Physics Move to RIKEN Installation Operation Accel-decel Metal IS Metal ions Cold model hot model Tuning Beam test Operation CRIB Move to RIKEN Modify Monitor Deflector HiECR Ion source Insulator Glaser lens 2008/4/4 4 Mesh Sputtering Design Improvement K=80 F0 focus Rf buncher SQUID monitor Design VIS R&D Insulator Condenser H=2,3 H=1 Sputtering IS

5 The main point of AVF Upgrade High Energy by K80, 15 N 5+ 9MeV/u, 10pµA Acceleration harmonics h = 1, 2, 3 (T) center region 2 (K-value 4 Now in used center region 2008/4/4 Energy per Nucleon (MeV/u) 5

6 1. Ion source What is advanced in 2007? HyperECR Ion source / Metal ions New ion source /Charge breeder ECR, Super ECR 2. Development of AVF Cyclotron New magnetic channel (beam loss improved) New RF power coupler (Dee voltage up at higher freq.) Improvement of E7 BT line ( Non destructive beam current monitor) 3. Upgrade of RIKEN/CNS AVF cyclotron Design of center region (calculation of beam dynamics) Acceleration test of 16 O 7+ 10MeV/u, 10.3MeV/u 2008/4/4 6

7 1. Ion Source A. Hyper ECR The half of the machine schedule of RIKEN cyclotron uses the our HyperECR ion source. B. Metal Ion Source Si, Ca, P extracted from HyperECR C. Super ECR 5.5K is continued D. CBECR Under the setup and vacuum test 2008/4/4 7 Y. Ohshiro

8 A. Hyper ECR Ion Source Table 1 Ion Energy C10 C01/I36 (MeV/u) (eµa) (%) H H Li Li C C N N O O Ne Ne Kr Extracted beam from AVF cyclotron Metal ion 2008/4/4 8 Y. Ohshiro

9 B. Development of Metal Ions Y. Ohshiro Center Fig. 2. The distance of the tips of the crucible and the rod placed in the plasma chamber. Table 2. Beam intensities of metallic ions obtained Ion Beam Intensity Charged Material (eµa) 7 Li Li pure metal (crucible) Bz (kg) Second stage ECR zone First stage ECR zone This year 7 Li Li pure metal (crucible) 28 Si SiO 2 (rod) 40 Ca CaF 2 (rod) 31 P P 2 O 5 (Crucible) ω ECR Fig. 1 Schematic drawing of Hyper ECR ion source together with mirror field distribution used for 40 Ca 11+ ions production. Plasma chamber, RF wall, Solid material, 2008/4/4 Movable rod, Sextupole magnet, MC1, MC2, Extractor 9

10 C. Development of SC-ECR Ion Source Y. Ohshiro, Tsukuba Univ. µ 2008/4/4 10

11 D. Development of CNS Charge Breeder Y. Ohshiro µ µ 2008/4/4 11

12 Charge Breeder (continued) 14GHz RF 0 20 cm TMP1 TMP2 TMP3 Voltage [kv] 0 Incident beam energy (10 kev +5 ev) Acceleration Deceleration E1 E 2 E 3 E 4 First stage ion source (IS) Volume type IS E.g. Ar +, 15 N + production Fig. 5. A cross-sectional view of the CNS Spattering type IS E.g. Li + - Cu + production charges breeding system and potential map Extraction voltage 10 kv + 5 V for injection of interest ions. Volume Beam transport system type ion source, Insulator (MC nylon), Max. Einzel lens voltage 20 kv (E 1 - E 4 ) Einzel lens (E 1-4 ), Charge breeder Deceleration voltage 10 kv ECR ion source (CBECR), Plasma Charge breeder ECRIS chamber, Decelerator, Conical wall. RF frequency 14 GHz Max. Mirror field 12 kg Table 3. Specification of each device Surface field of sextupol 10.4 kg designed. Correction coil AT (C 1 - C 3 ) 2008/4/4 Acceleration voltage 10 kv 12 V Y. Ohshiro

13 2. Development of AVF in 2007 Magnetic Channel Old Magnetic channel was replaced by new one Beam loss is improved due to widest channel 2008/4/4 13 A.Goto RIKEN

14 3. Upgrade of RIKEN/CNS AVF cyclotron 1. Study of Beam dynamics for 16 O 7+ 10MeV/u AVF beam dynamics modeling in the 3D E-map Bunch acceleration from the inflector exit to the medium energy Optimization perspectives Confirmation of beam loss due to interaction with RF shield 2. Beam monitor 2008/4/4 14

15 1. Study of Beam dynamics for 16 O 7+ 10MeV/u S.Kubono, S.Watanabe CNS Sergey B. Vorozhtsov, Evegeny Perpelkin JINR Dubna A.Goto RIKEN 2008/4/4 15

16 N is free parameter? E b up at r N =0.714 m --- constrain 1, V d =fixed --- constrain 2 So, B(r) ;should be increased, but V d =fixed, Question = N is free parameter? r1 is fixed at 1 st dee channel for passing the injected ECR beam constrain 3. If B(r 1 )r 1. is increased in accordance with E b up, so Vd should be increased to maintain constant r be inconsistent r 1 r N 2008/4/4 16

17 Equation ρ = A z B 2 2 T [kgcm] A=14 z=5 T =8.2[MeV/u] 14 N 5+ Bρ = x sqrt(14 x8.2 /5 2 ) = [kgcm] f 0 = v/2πρ 2 T β = v = cβ E0 Frf = hf = 0 hv 2πρ Vrf = TA / q Nhn q = ze qb( r) r = 2mqV ( k N) N d + -- Eq.1 N is turn number, N=1,2,3, 110,, N 2008/4/4 17

18 Constrain Eq. 1 seems that we could E b up by increasing B(r) and N. Constrain 3 at 1 st turn requires V d to maintain constant r 1. It is inconsistent to constrain 2. Eq. 1 may allowable r1 but limited N. 2008/4/4 18

19 Beam simulation of C.R. Problem formulation To what extent the position of the central region (C.R.) trajectory of the 14 N 5+ ions (16.3 MHz) will change at the channel of the tip of the dee electrode when the dee voltage is lower than the nominal value of 46.7 kv by 10 or 20%? Parameters The nominal inflector position and voltage = 3.14 kv. The nominal energy of the injected particles = 52 kev. The magnetic and electric field distributions were those that were used for 14 N 5+ beam acceleration (16.3 MHz). The first gap crossing RF phase = /4/4 19

20 Trajectories U Dee = kv 90% U Dee = kv 80% U Dee = 46.7 kv 100% 2008/4/4 20 E.E. Perepelkin and S.B. Vorozhtsov JINR, Dubna

21 Scenario of AVF tuning for 16 O 7+ 10MeV/u η = (q/m)v dee cos(-φ)/f 2 dee Average η of 11 Ne 7+, 14 N 6+, 28 Si 9+ and 7 Li 2+ is obtained at (σ n =1.0045x10-3 ), where φ is 26. V dee =52.5kV, F dee =19.374MHz are recommended parameters at η to accelerate 16 O 7+ up to 10MeV/u. V dee =48kV, F dee =19.374MHz are given parameters for acceleration of 16 O7+ 10MeV/u even if out of value of η. So, expected orbit radius r 1 at 1 st Dee channel is 38mm smaller than recommended r 1 of 40mm. After that, expected turn number N is increased up to 119 even if recommended turn number is 110. In order to make a corrected acceleration orbit from reference orbit, we may adjust φ by changing an exit angle of inflector and also corrects trim coil currents of 1 st and 2 nd trim coil magnets. 2008/4/4 21 S.Watanabe CNS

22 Result 16 O 7+ was achieved. May S.Watanabe, S.Kubono, Y.Ohshiro, A.Goto 16 O 7+ was achieved in Jan S.Watanabe, S.Kubono, Y.Ohshiro, A.Goto, K.Hatanaka 2008/4/4 22

23 2. Beam monitor E7 core monitor-off line test Extraction monitor R&D Sensitivity Pink: Low environment noise Black: Higher environment noise X: beam current (µa) Installation> March 08 Y: Pick up level (dbm) Detector: Metal plate Composition Tantalum Location Extraction channel between Deflector and Magnetic channel (29mm) 2008/4/4 23 S. Watanabe CNS

24 3. Schedule ~March 2008 Beam monitor E7-BT > Installation of core monitor Center region 3 rd CNS-JINR-RIKEN collaboration: Feb.18-March 16 Subject: Study of Center region and beam extraction at h=2 S. Kubono, S.Watanabe, Sergey B. Vorozhtsov, Alexey S. Vorozhtsov, Evegeny Perpelkin, A.Goto 2008/4/4 24

25 Summary Status of ECR Ion sources HyperECR, Metal IS, Super ECR, Charge breeder are advanced. Development of the AVF cyclotron Magnetic channel is improved. Dee voltage at higher frequency is improved. Upgrade of AVF cyclotron Energy up by increasing turn number has been succeeded. Beam monitoring devices are in progress. 2008/4/4 25