ISSN 15474771, Physics of Particles and Nuclei Letters, 2010, Vol. 7, No. 4, pp. 256–272. © Pleiades Publishing, Ltd., 2010. Original Russian Text © G.G. Gulbekyan, S.N. Dmitriev, B.N. Gikal, S.L. Bogomolov, O.N. Borisov, V.A. Verevochkin, A.A. Efremov, I.A. Ivanenko, G.N. Ivanov, N.Yu. Kazarinov, V.I. Kaza cha, I.V. Kalagin, I.V. Kolesov, S.V. Pashchenko, M.N. Sazonov, A.V. Tikhomirov, J. Franko, M.V. Khabarov, K.K. Kadyrzhanov, A.Zh. Tuleushev, 2010, published in Pis’ma v Zhurnal Fizika Elementarnykh Chastits i Atomnogo Yadra, 2010, No. 4 (160), pp. 424–445.
PHYSICS AND TECHNIQUE OF ACCELERATORS
DC350 Accelerator Complex G. G. Gulbekyana, S. N. Dmitrieva, B. N. Gikala, S. L. Bogomolova, O. N. Borisova, V. A. Verevochkina, A. A. Efremova, I. A. Ivanenkoa, G. N. Ivanova, N. Yu. Kazarinova, V. I. Kazachaa, I. V. Kalagina, I. V. Kolesova, S. V. Pashchenkoa, M. N. Sazonova, A. V. Tikhomirova, J. Frankoa, M. V. Khabarova, K. K. Kadyrzhanovb, and A. Zh. Tuleushevb a
bInstitute
Joint Institute for Nuclear Research, Dubna, Russia of Nuclear Physics, National Nuclear Center, Almaty, Republic of Kazakhstan Received November 23, 2009
Abstract—The DC350 accelerator complex is described and its technical characteristics are presented. DOI: 10.1134/S1547477110040047
INTRODUCTION Synthesizing new elements of the periodic table is the most fundamental and important direction of modern nuclear physics and radiochemistry. Long term research programs in this direction have been approved in Dubna (Russian Federation); Berkeley (United States); Darmstadt (Germany); Orsay (France); RIKEN (Japan); and, most recently, in Lanzhou (China). Currently, the leader in this direc tion is the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research (Dubna). Formulating experiments on the synthesis of new superheavy elements with Z = 120–124 in reactions with extremely low (presently unachievable) cross sec tions of 0.1–0.2 pb requires the creation of a new accelerator complex, which makes the production of iron, nickel, and cobalt ion beams with record intensi ties feasible. The basic component of such a complex is a cyclic heavy ion accelerator whose parameters are essentially higher than those of all existing similar types: (i) the acceleration of 48Ca, 50Ti, 58Fe, and 64Ni ions to ≈5 MeV/nucleon; (ii) a beam intensity on the target of up to 2–3 × 1013 s–1; (iii) stepfree particle energy variation within 4.5– 5.5 MeV/nucleon; (iv) monoenergetic beam of ±10–3…5 × 10–3, depending on the intensity; (v) a beam energy instability of 2 × 10–3; (vi) a beam spot size on the target with a maximum diameter of 10 mm; (vii) beam lines to 3–5 experimental setups; (viii) diagnostic systems should provide beam transportation with minimum intensity from 109 s–1; (ix) continuous operation over 2–3 months.
A sketch design of the DC350 accelerator com plex satisfying the above requirements was developed at the Laboratory of Nuclear Reactions at the Joint Institute for Nuclear Research (Dubna) in collabora tion with the Institute of Nuclear Physics (Almaty, Kazakhstan). The basis of the DC350 accelerator complex is the isochronous cyclotron DC350 capable of producing highintensity heavy ion beams from Li to Bi with an energy of 3–12 MeV/nucleon. The com plex also includes an ion source based on electron cyclotron resonance method (ECR), producing low energy (up to 25 keV per unit charge) ion beams with currents up to 400 μA. The scientific program of the new complex is mainly aimed at fundamental studies in the field of nuclear physics, such as the synthesis and investigation of the nuclear physical properties of superheavy ele ments, radiochemical identification, and an investiga tion of the chemical properties of synthesized ele ments. The extension of the mass range of accelerated ions toward lighter (C, O) and heavier (Xe, Bi) ions and the increase in the energy range of the produced ion beams is extremely important for test experiments and extending the functional capabilities of the complex, including the investigation of other classes of nuclear reactions, isotope production for radio medicine and ecology, and studies in the field of condensed matter physics. The extended capabilities of the complex will make applied studies, such as the production and application of track membranes, surface modification, ion implantation nanotechnology, and testing elec tronic components of satellite and aircraft equipment, feasible.
256
1000
34200 3000 2000
6
Supports of ECR source service area
2000 Cyclotron hall 113 5760 1000
43660
Canyon 1
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n tio rac ext nel 2 am n Be cha
Be am
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15115
1500
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Canyon 3, gasfilled separator (II class) equipment, 117 item 12 116
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Be am e cha xtrac nn tion el 4
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119 equipment, item 13 Control room of channels 3 and 4
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2000 Canyon 5, radiochemical branch (II class) equipment, item 14 Be
1500
3048
15115
120 Room for control equipment of channel 5
0
257 2000
DC350 ACCELERATOR COMPLEX
15
Fig. 1. Schematic diagram of the DC350 complex.
1. STRUCTURE OF THE DC350 COMPLEX
2. ECR ION SOURCE
The DC350 project is based on new developments and technologies obtained while creating and operat ing cyclotrons at LNR, such as U400, U400M, IC100, DC60 (Republic of Kazakhstan). A sche matic diagram of the DC350 complex is shown in Fig. 1. This complex includes the following: (i) an ECR ion source; (ii) an axial injection system for the beam; (iii) a DC350 isochronous cyclotron; (iv) five beam lines; (v) physical setups; (vi) technological equipment. Multicharged ions produced by the ECR source are transported along the injection channel to the center of the cyclotron, where the beam is accelerated to the final energy. The magnetic field of the cyclotron has a foursector structure. The RF accelerating system consists of two quarterwave resonators. The RF sys tem is powered from two generators operating at a fre quency of from 6.45 to 13 MHz. The extraction system consists of the electrostatic deflector and the focusing magnetic channel. The beam line for accelerated beams has four channels for scientific studies and a specialized channel for applied studies.
The ion source should give both relatively high ion beam intensities (beam currents up to 400 μA for 7Li1+, 16O2+, 40Ar8+ ions) and highly charged ion beams (for example, 132Xe22+, 209Bi43+). According to it, the main requirements for different subsystems of the ion source can be formulated as follows:
PHYSICS OF PARTICLES AND NUCLEI LETTERS
(i) the RF power supply system of the ion source should give sufficiently dense plasma containing mul ticharged ions for obtaining the required ion beam intensities; (ii) the magnetic system of the ion source should provide the ion confinement time necessary for obtaining ions with required charge. The magnetic field level should be sufficient for creating a closed res onance region for the chosen RF pumping frequency; (iii) the vacuum system of the ion source should give a residual vacuum in the region of the plasma chamber of the ion source that is not worse than 1 × 10–7 Torr and, during the source operation, in a range of (2–7) × 10–7 in the extraction region. (iv) the extraction system of the ion source should yield the extraction and formation of ion beams with a total intensity of up to 5 mA and a beam emittance of no higher than 200 π mm mrad for the required charge.
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Table 1. ECR source parameters Basic parameters
Warm ECR
Superconducting ECR
RF generator frequency, GHz Number of solenoids Axial magnetic field, T Radial magnetic field, T Consumed power, kW Water pressure in cooling system, atm Dimensions, mm Cryosystem
18 3 1.4 1.3 170 15 ∅500 × 550 Absent
18 4 2.1 1.3 30 4 ∅690 × 570 Cryocooler 40 K (35 Wt), 4 K (1 Wt)
Applying a working frequency of 18 GHz in the ECR source of the DC350 cyclotron made it possible to obtain the required intensities. For this pumping fre quency, the resonance magnetic field is Bres = 0.64 T and the maximum magnetic field level reaches 2.0 T. The radial magnetic field should be Bradial ≈ 2Bres ≈ 1.3 T. The creation of axial magnetic fields of such a level in “warm” magnetic systems is difficult, because the “miron” used for magnetic field formation in the source operates in the saturation regime. These mag netic fields can be rather easily achieved in a supercon ducting magnetic system, and the required radial mag netic field level is achieved with modern permanent magnets. A comparison of the parameters of warm and superconducting ECR sources is given in Table 1. The design of a superconducting magnetic source system for DC350 was based on projects used in cre ating magnetic systems for DECRISSC (18 GHz) [1] and DECRISSC2 (14 GHz) [2] sources.
The main specific feature of magnetic systems of these sources is the application of a compact Gifford–McMa hon cryocooler with a power of 1 W for cooling supercon ducting coils. A general view of the DECRISSC3 super conducting magnetic system is shown in Fig. 2. Both warm and superconducting variants of ECR source possess certain advantages and disadvantages. The advantage of the warm variant is its relative sim plicity in manufacture and maintenance; its disadvan tage is its high energy consumption for a lower mag netic field level. The advantage of the superconducting variant is its much lower energy consumption; the dis advantage is the maintenance costs connected with the necessity of periodic (each 10000–15000 h) preven tive treatment of the cold head, which requires heating the magnetic system cryostat and a reserve cold head. There are pulsetube cryocoolers with a service life of more than 30000 h. 843
610
486
392
212
1174
714
585
Fig. 2. ECR source DECRISSC3. PHYSICS OF PARTICLES AND NUCLEI LETTERS
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DC350 ACCELERATOR COMPLEX
PHYSICS OF PARTICLES AND NUCLEI LETTERS
SECR
IM90
IBN1
Maggnet DC350 yoke
IS1 IS2
IBN2 IS3 Plug
I
Fig. 3. Schematic diagram of a channel.
Envelopes, cm
ECR IM90
8
IS1
IS3
Aperture
4 0 –4 –8 0
100 200 300 400 500 Distance, cm
Fig. 4. Envelopes of 48Ca6+ beam.
Envelopes, cm
3. AXIAL INJECTION SYSTEM The axial injection system shown in Fig. 3 is desig nated for ion transportation from the superconducting ECR source (SECR) to the center of the cyclotron. The channel offers the efficient injection of ions from lithium to bismuth with a chargetomass ratio of 4.8– 9.6 [3]. The main optical elements of the channel are the IM90 analyzing magnet, three IS1–IS3 solenoids, and the correcting dipole magnets. The considerable reduction of the distance between SECR and the ana lyzing magnet and an increased voltage of 25 kV for extraction from SECR make it unnecessary to place the focusing solenoid between the source and the mag net. This weakens the negative influence of the beam field on its emittance [4]. Beam focusing in the chan nel is performed by the edge field of the magnet and IS1 and IS3 solenoids. IS2 solenoid is used as the cor recting solenoid. The IM90 analyzing magnet has a turning radius of 350 mm and a gap between poles of 120 mm. The aper ture of the vacuum chamber in the magnet is 110 mm. Screens reducing the edge field extension are installed at the input and output. A 3D simulation of the mag netic field distribution for this magnet [5] gave a correct determination of the edge angles of the poles (29.5°) for the axial symmetry of the beam after the turn. The injected ion beam is turned to the median plane of DC350 using spiral inflector I. Two variants of inflectors with magnetic radii of 25 and 45 mm are used in the whole range of accelerated particles for providing optimal beam injection conditions. Linear (IBN1) and sinusoidal (IBN2) bunchers are used for increasing acceleration efficiency. The linear buncher is situated at a distance of 275 cm and the sinusoidal buncher is 85 cm from the median plane of the cyclotron. Both bunchers are manufactured in the form of two metallic grids with antiphased RF voltage supplied to them. The voltage amplitude at the linear buncher varies from 600 to 900 V, approximately lin early, as the beam current increases from 0 to 200 μA. The voltage amplitude at the sinusoidal buncher in this case varies from 400 to 650 V. The bunching efficiency is 20% for the maximum beam current. The variation of beam envelopes for 48Ca6+ ions with a current of 190 μA along the channel is shown in Fig. 4, and their behavior near the inflector is shown in Fig. 5. The beam diagnostic system consists of the Faraday cup and the needle scanner. The slit collimator and the pepperpot device are used for beam current variation. The vacuum pumping system at the horizontal sec tion consists of three turbine pumps with a perfor mance of 150 l/s each. The pumps are situated at both sides of SECR and at the vacuum chamber of the mag
259
Aperture
4 2 0 –2 –4 525
535
545
555 565 Distance, cm
Fig. 5. Envelopes of 48Ca6+ beam near the inflector.
net. The cryopump with a performance of 800 l/s is installed at the output of SECR. At the vertical sec tion, pumping is performed by one turbine pump with a performance of 500 l/s and one cryopump with a performance of 800 l/s installed at the diagnostic block. The calculated average pressure in the beam
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Ions energy, MeV/nucl
12 11 10 9
48Ca10+/2.9 pµA × 13.00 MHz 0.015 T 48 9+
Ca /4.0
Mass to charge ratio
5.33 48
0.012 T 6
Ca8+/5.1
8 0.010 T
7
48 0.009 T
Ca7+/5.9 3
6.86
6
0.008 T
4.2 4.0 3.8 3.6 3.4 3.2 3.0
0.007 T
5
48 0.006 T
2.8
Ca6+/6.3
8
2.6
132Xe14+
2.4
Ions frequency, MHz
Extraction radius 1.76 m generator frequency 6.45 – 13.0 MHz *Extracted ions intensity Harmonic mode 3rd harmonic (expected, coeff. 0.2)
Fig. 7. Electromagnet of the DC350 cyclotron (one half).
4 0.005 T 84
132
Xe10+ 84
3
Xe15+
48
9+
Xe
9.6
Ca5+/6.4
6.45 MHz
2.2
1.36 1.44 1.28 1.24 1.32 1.40 1.48 Cyclotron center magnetic field, T Fig. 6. Working diagram of the DC350 cyclotron.
line of the channel is 1 × 10–7 Torr, and possible parti cle losses do not exceed 10%.
Table 2. Basic parameters of the DC350 cyclotron magnet Magnet dimensions (length/width/height), m 9.13/4.92/4.0 Pole diameter, mm 4000 Number of sectors 4 Gap between poles, mm 400 Pole–sector gap, mm 25 Gap between (plane) sectors, mm 80 Gap between central plugs, mm 190 External sector diameter, mm 3960 Internal sector diameter, mm 258 Average magnetic field at extraction radius, T 1.24–1.5 Magnet weight, t 1195 Weight of the heaviest part, t 30 Maximum number of ampere turns in the winding 340480 Maximum current of power supply source, A 760 Power of winding power supply system, kW 265 Winding weight, t 20.1 Number of radial correcting coils 9 Number of azimuthal correcting coils 4 Nominal working current 15 Power of correcting coil power supply system, kW 5
4. CYCLOTRON MAGNETIC STRUCTURE The designed magnetic structure makes it possible to form an isochronous magnetic field for working regimes of DC350 cyclotrons shown in Fig. 6. The cyclotron electromagnet shown in Fig. 7 has an Etype shape and consists of a yoke, pole assem blies, excitation windings, and correcting coils. Four pairs of sectors with zero spirality are situated in the working gap of the magnet. Each sector is equipped with removable side shims which are part of the sector assembly. The azimuthal and axial process ing of the sector side shims makes it possible to intro duce the necessary correction into the magnetic field distribution in the course of the final formation of iso chronous acceleration conditions. Two assemblies of azimuthal correcting coils and nine pairs of radial correcting coils are situated in the working gap of the cyclotron electromagnet between the sectors and the pole; this allows the operative adjustment of the magnetic field when changing the cyclotron acceleration regime. The main parameters of the cyclotron magnet are given in Table 2. The average magnetic field for several excitation levels of the main coil of the magnet is shown in Fig. 8. The contributions of correcting radial coils for the nominal excitation current are shown in Fig. 9. 5. INFLECTOR AND CENTRAL REGION OF CYCLOTRON The injected ion beam is turned from the axial channel to the median plane of the cyclotron using the spiral inflector and is captured to be accelerated in specially formed accelerating gaps of the central regions. For providing optimal beam injection conditions in a wide range of A/Z variation and magnetic field level
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DC350 ACCELERATOR COMPLEX B, T 1.60 1.55 1.50 1.45 1.40 1.35 1.30 1.25 1.20 1.15 1.10
dB, T 0.010
261
CR0 CR1 CR2 CR3 CR4 CR5 CR6 CR7 CR8
DC350 Coil contributions at I = 15 A Field level B = 1.4 T
0.008 0.006 0.004 0.002 0 –0.002 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 R, m
0
0.4
0.8
1.2
1.6
2.0
2.4 R, m
Fig. 9. Contributions of correcting radial coils.
Fig. 8. Average magnetic field of the DC350 cyclotron.
Fig. 10. Schematic diagram of the center of the DC350.
in DC350, two inflector variants with the magnetic radii ρm = 35 and 43 mm are used. The inflector elec tric radius Ae in both variants is 45 mm; in this case, the voltage at the inflector electrodes does not exceed ±7 kV. The radial positioning mechanism is used for the establishment and online adjustment of the inflec tor position at the cyclotron center. The central region of the cyclotron forms the capture conditions for the acceleration of the injected beam from starting radii of 65–81 mm, depending on the applied inflector. The accelerating electric field provides vertical beam focusing at the first turns in the region of low mag neticfield flatter. A schematic diagram of the central PHYSICS OF PARTICLES AND NUCLEI LETTERS
region and 48Ca7+ beam trajectory at the first turns is shown in Fig. 10. 6. EXTRACTION SYSTEM FOR ACCELERATED ION BEAM It has been proposed that the electrostatic deflector be used to deflect the internal beam and extract it from the accelerator. The deflector represents two bent par allel plates (“septum” and “potential” plates), and the electric field deflecting the beam from the cyclotron chamber is created between the plates.
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DC350 Bav = 1.42, 48Ca7+ A/Z = 6.857 W = 6.3 MeV/amu
Θ = 0°
10
–
66 °
–0.5
ES D
:– 24 ...
–1.0 –1.5 Θ = –158°
–2.0
R = 333 cm
–2.5
Θ = –90°
–3.0 –3.5 –3.0 –2.5 –2.0 –1.5 –1.0 –0.5
0
0.5
1.0
1.5
2.0 X, m
Fig. 11. Beam extraction trajectory.
Beam extraction was simulated for ions with A/Z = 4.8–9.6 and energies W ≈ 3.0–11.0 MeV/nucleon according to the working diagram. Calculated magnetic field maps were used for calculations. The analysis of the beam dynamics in these magnetic fields showed that the maximum average orbit radius is ≈176 cm. Ions 48Ca with Z = 5+, 6+, 7+, 8+, and 9+ were con sidered in numerical calculations. The voltage at the deflector was chosen with account of matching the extracted beam and the beam line system. The deflector was situated in the valley and its azi muthal length was 42°. The deflector input and output radii correspond to R ≈ 1750–1810 mm. The deflector plate curvature corresponds to the extraction trajec tory. The radial gap between the “septum” and the “potential” plates was 10 mm. The maximum voltage at the potential electrode was 100 kV. The deflector consists of two sections (≈650 mm each). The maximum extracted beam power is ≈2 kW. Therefore, the initial part of the septum plate is manu factured from tungsten (W) or tantalum (Ta) with a thickness of ≈0.1–0.2 mm and a height of 40 mm. The other part of septum is manufactured from copper (Cu) with a height of 40 mm and a thickness of 1–20 mm. Potential plates of both sections are manufactured from Al or stainless steel. The height of the potential electrode is ≈60 mm. For reducing the probability of electric breakdowns, an electron trap is created in it (a hollow in the potential electrode plate with a height of 20 mm and a depth of 0.5 mm).
Both potential electrodes are fastened on three insulators (two reference and one bushing insulators). The insulator length is ~200 mm and the material is Al2O3 or Macor (<15 kV/cm). The vertical gap between the reference insulators and the frame is not smaller than 60 mm. The deflector structure is situated inside the dur alumin frame. Cladding by molybdenum plates with a thickness of 1 mm happens from above and below. The frame is cooled by water (2 l/min). For compensating the influence of the edge mag netic field of the cyclotron, the focusing magnetic channel is used. It represents a set of steel elements (steel 10) in an external magnetic field which forms the required magnetic field shape for horizontal beam focusing. The channel is situated between the sectors. The radii of magnetic channel input and output are R ≈ 1915–2025 mm. The total channel length is ≈850 mm. Figure 11 shows the output ion trajectory. The radial emittance at the input of the deflector Er = 5 mm 3 mrad π = 15π mm mrad, and the vertical emittance Ez = 5 mm 2 mrad π = 10π mm mrad. The energy spread δW = ±1%. Figure 12 shows an example of extracted beam envelopes, Fig. 13 shows the emit tances at the input of beam line system, and Fig. 14 shows the magnetic channel of the extraction system.
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DC350 ACCELERATOR COMPLEX Envelopes, cm 3.0
15
5 (a)
env Xs env zs
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MC
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0
0
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dZ
0.5
5
–5
dX
1.0
–15 –30
0 20
40
60
–10 0 10 30 ΔX, mm
80 100 120 140 160 Θ, °
Fig. 12. Beam envelopes without magnetic channels and using the focusing magnetic channel.
Channel cross section at azimuth 89
Magnet sector
40
Z = 36.5
Z = 35.0
35 30
Z = 26.5
25 Z = 15.5 Beam axis
20 15 10 5
Z = 16
Z = 14 Z = 11.5
Working aperture (beam)
0
Median plane
–5 R = 1980
–10 –15
R = 1956.7
R = 1966.4
R = 1924.3 R = 1933
–20 –25 R = 1954
–30 –35
R = 1962.8
–45 –45
R = 1972.8
Magnet sector
–50 1925 1935 1945 1955 1965 1985 1975 1920 1930 1940 1950 1960 1970 1980 R, mm
Fig. 14. Magnetic channel of the extraction system. PHYSICS OF PARTICLES AND NUCLEI LETTERS
–5 –10 –5
0
Fig. 13. Extracted beam emittance.
Z, mm 50 45
(b)
10 Δα, mrad
2.5 2.0
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Table 3. Basic RF system parameters Accelerated ions, A/Z Ion energy, MeV/nucleon Acceleration harmonic Voltage at the dees, kV RF system voltage, MHz Power of RF power supply system, kW Voltage phasing precision at the dees Amplitude stability Accelerating gap, mm Working travel of shortcircuiting plates, mm Cooling water flow, l/min
4.8–9.6 3–12 3 80 6.45–13 2 ⋅ 20 1 10–3 20–40 1986 2 ⋅ 27
7. RF ACCELERATING SYSTEM The accelerating system of the DC350 cyclotron yields the acceleration of ions with A/Z = 4.8–9.6 to energies in a range of 3–12 MeV/nucleon. At each turn, the ion beam is accelerated in four gaps formed by two ~42° dees and antidees.
Axial dimension, mm
Axial dimension, mm
The dees are situated in the opposite sides of the valleys. The dees and antidees, along with the resona tor tanks, form two resonator circuits. RF voltage from two generators is supplied to each resonator circuit via the coupling loop. The resonance system is adjusted to the working frequency using shortcircuiting plates, 800 700 600 500 400 300 200 100
and the fine tuning of the resonance frequency is per formed by the rotation of the shortcircuited loop. The accelerating system of DC350 cyclotron con sists of two sets of resonator tanks and rods, shortcir cuiting plates, reducers, dees and antidees, adjustment devices, shortcircuiting drives, automatic frequency trimmers, coupling loops, water transportation chan nels, and supports. The basic parameters of the RF system of the DC350 cyclotron are given in Table 3. The geometric dimensions of the cyclotron RF system are shown in Fig. 15. 8. VACUUM SYSTEM The accelerator vacuum pumping system should provide the following: (i) pumping in the pressure range P ≤ 5 × 10–8 Torr; (ii) oilfree pumping; (iii) a high starting pressure of P ≤ 5 × 10–2 Torr; (iv) insensitivity to gas loads in the case of vacuum failure; (v) a high pumping rate for minimal dimensions; (vi) the possibility of leak search; (vii) the possibility of remote (computer) control. A combination of turbine and cryopumps satisfies these requirements most completely. Turbine pumps are used due to the necessity of leak search and the creation of a forevacuum in the accelerator chamber (a)
ΔL = 1760 mm +390 mm
A +2150 mm
A
0
500
1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 Resonator legth, mm (b)
0
500
1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 Resonator legth, mm
800 700 600 500 400 300 200 100
Fig. 15. Basic geometric dimensions of the DC350 RF system. Cross section of resonance system: (a) view from above and (b) side view. PHYSICS OF PARTICLES AND NUCLEI LETTERS
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265
CFP21 CLV2 CV21 CG3
CVP11
CVP10
CV21
CP10
CP11 CGVP11 CG8
CGVP10 CVV1
CFP22 CVP6
CG7 CP12
CP3 CGVP3
CVP4 CVP3 CP4 CGVP4
CP6
CVP12
CGVP12 CGV1
CFP31
IGV2 CVR1
CVR2 CV31
CFVC1
CG4
INF
CV32 CLV3
CFVinf CG9
CVVinf
CP1
CP9
CVP1 CGVP9 CGVP7
CVP9
CFV1 CGVP7 CP7
CFP32
CGVP2 CP2 CVP2
CP5 CVP5
CG6 CGVP8 CP8
CG5 CVP7
CVP8
CV1 CFP1
CG1
CV3 CG2
CRP1
CLV1 CV2
Fig. 16. Schematic diagram of the vacuum pumping system.
with P ≤ 10–5 Torr, which makes the durable operation of cryopumps without regeneration possible. Stop valves will be equipped with VAT Series 14 and VAT Series 12 (VAT, Switzerland) sliding shutters. This series is produced with a wide range of standard sizes and has drive modifications (manual and elec tropneumatic). The measurement equipment will include TPR017 sensors of the Pirani type (a forevacuum measurement in the range of 1000–5 × 10–4 Torr) and IKR050 of the Penning type (a measurement of high vacuum in the range of 5 × 10–3–10–9 Torr). These sensors will yield high reliability, insensitivity to vacuum worsening (up to one atmosphere), a vacuum measurement within P = 10–3–1 × 10–8 Torr (for high vacuum sensors), and the possibility of operating in strong magnetic fields. TPG300 with four vacuum measurement channels is planned for use as the vacuummeter for these sensors. These measurement systems were proven to work well in operation at the U400 axial injection complex. The following forevacuum lines will be used for the accelerator operation: (i) a forevacuum pumping line in a range of 760–2 × 10–1 Torr. There are plans to use a DUO 250 fore pump (PFEIFFER VACUUM, Germany) with a rate of ~70 l/s. Pumping in the range of 2 × 10–1–1 × 10–2 Torr is performed via the same foreline using the Roots type pump with a rate of ~500 l/s. The WKP 200 AS pump (PFEIFFER VACUUM, Germany) is considered PHYSICS OF PARTICLES AND NUCLEI LETTERS
such a pump. This foreline is also being planned to be used for the regeneration of cryopumps; (ii) a turbine pump forepumping line. There are plans to use a DUO 120 forepump (PFEIFFER VACUUM, Germany) with a rate of ~33 l/s. For faultfree accel erator operation, two pumps will be installed, with the possibility of commutation in this line; (iii) forepumping lines of correcting coils, probe gates, and an inflector. There are plans to use the DOR 65 forepump (PFEIFFER VACUUM, Ger many) with a rate of ~18 l/s. The accelerator chamber is pumped in five stages for ~70 h: (i) first stage: forevacuum chamber pumping to P ≤ 2 × 10–1 Torr using the CFP1 forepump; (ii) second stage: forevacuum chamber pumping to P ≤ 1 × 10–2 Torr using the CRP1 forepump; (iii) third stage: chamber pumping using CP1–CP6 turbine pumps. The regeneration of CP7–CP12 cry opumps and their activation are performed simulta neously. By the time the working regime is reached by cryopumps (T = 16–18 K), the pressure in the cham ber is P ≤ 5 × 10–5 Torr; (iv) fourth stage: chamber pumping using P7–P10 turbine pumps and P1–P6 cryopumps; (v) fifth stage: after the magnetic field being switched on, the CP1 and CP3 turbine pumps are turned off.
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Deflectors
Inflector
Upper part of the dees
Fig. 17. View of DC350 cyclotron.
Channel 1
T1B4
604 6
T2B4 Channel 2 T1Q6
1800
T1Q5 T1CM1
Channel 0
T2Q6 T2Q5 6016 T2CM1
6490 TCMH TOB1 TCMV
TOB2
TOB3 TM
T3CM1
T0Q1 T0Q2 T0Q3 T0Q4
T3B4
Channel 3
T3Q5 T3Q6
T4CM1 T4Q5 T5CM1
T4Q6 T4B4
T5Q5
Channel 4
T5Q6
T5B4
Channel 5
Fig. 18. Schematic diagram of beam lines.
A schematic diagram of the vacuumpumping sys tem of the DC350 cyclotron is shown in Fig. 16. 9. DC350 CYCLOTRON CONFIGURATION The position of basic elements of the DC350 cyclotron is shown in Fig. 17.
10. BEAM LINES The schematic diagram of beam lines for the DC 350 cyclotron is shown in Fig. 18. The beamline system consists of five channels used for scientific and applied studies. The TCM out put magnet corrects the beam axis within ±2.5°. Two doublets of T0A1–T0Q4 quadrupole lenses form the
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(a)
30
Halfsize ax, ay, mm
Halfsize ax, ay, mm
DC350 ACCELERATOR COMPLEX
H 20 10 V 0
400
800 Length, cm
267 (b)
30 H 20 10 V 400
0
800 Length, cm
Fig. 19. Beam envelopes in (a) channel 1 and (b) channe l 4.
parallel beam at the input of the TM commutating magnet. Then the beam is transported by the optical elements of each channel and is formed on the target according to the requirements of the physical experi ment. The TM magnet makes it possible to turn the ion beam by ±60° (channels 1 and 5) and ±30° (chan nels 2 and 4). If TM is switched off, the ion beam is transported along channel 3. Figure 19 shows an example of calculated horizon tal (H) and vertical (V) halfsizes of the ion beams as functions of the length in channels 1 and 4 [6]. Devices for measuring beam parameters will be sit uated in eight T0B1–3, T1–5B4 diagnostic blocks. Faraday cups will be used to measure the beam cur rent. Mobile luminophors with TV cameras and nee dle scanners will be used for the beam profile and par ticle density distribution measurement in the beam cross section. There will be aperture diaphragms in front of the TM distributing magnet and at the end of each channel to adjust the beam transportation along channels. Slit collimators will be used to change the beam intensity and transverse density distribution.
The technical characteristics are briefly given in Table 4. The structural diagrams of power supply are shown in Figs. 20 and 21. 12. COOLING SYSTEM The cooling system of the DC350 accelerator complex is constructed according to the doublecir cuit principle. The circulating heat carrier of circuit I (deionized water with a conductivity of 5.5 μS/cm) is connected with a circulating cooling agent of circuit II via heatexchanger. Technically, circuits I and II of the cooling system are closed circulation systems without jet discontinu ity. During the summer, heat is utilized via the cooling unit. During the winter, the remote dry cooling tower (dry cooler) is used. All pumping equipment is pro vided with a backup. The monitoring and control sys tem automatically operates the devices of the water cooling system and controls temperatures and heat carrier flows through the devices of the accelerator complex. A schematic diagram of the cooling system is shown in Fig. 22.
11. POWER SUPPLY SYSTEM
13. CONTROL SYSTEM
The power supply of the DC350 cyclotron and experimental setups comes from AC network 3 × 380/220 V, 50 Hz with a TNS grounding system.
The control system of the DC350 accelerator is being developed at the Laboratory of Nuclear Reac tions of the Joint Institute for Nuclear Research. The
Table 4. Brief technical characteristics Setup DC350 cyclotron Experimental setups Total
Total established power, kVA
Total consumed power, kVA
Active consumed power, kVA
1497
1350
1150
850
590
480
2347
1940
1630
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Source ECR
UHF
Cryo pump
7 kVA
Cryo cooler
15 kVA
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Cooling units
Pump modules
S = 320 kVA
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WC
2 kVA
RF generator
HF
2 kVA
S = 132 kVA
RF generator
130 kVA
ShR4
IM90
20 kVA
Fore pumps
66 kVA
Vacuum pumping station
Cryo pumps
44 kVA
500A30V
IS2
20 kVA
S = 110 kVA
500A30V
IS1
20 kVA
ShR5
500A30V 500A30V
TM
CM
800A 375V
80 kVA
400 kVA
ShR2
S = 50 kVA
Injection
30 kVA
Vacuum workshop
Test bench
ShR6
500A30V
TCMH
20 kVA
S = 20 kVA
Cyclotron MPS
20 kVA
Control room
DC350 control panel
ShR7
Injection MPS
20 kVA
S = 250 kVA
Cyclotron
30 kVA
Direction MPS
20 kVA
S = 20 kVA
Personnel of the electric workshop
Electric workshop
ShR8
S = 25 kVA
Six office rooms
ShR9
30 kVA
Workshop for radioactiv units
ShR10 S = 20 kVA
Pconsumed = 1150 kW;
Direction
Room of power supply and control system
Cyclotron DM
20 kVA
S = 1497 kVA Sconsumed = 1350 kVA
Fig. 20. Structural diagram of the power supply of DC350. S is the total established power (kVA), Sconsumed is the total consumed power (kVA), Pconsumed is the active consumed power (kW), and ShR is the distribution cabinet.
Room for the water supply system
Water preparation
ShR3
ECR source platform in DC350 hall
2 kVA
S = 50 kVA
16 kVA
ShR1
Distribution switchboard of building RShch380/220 V
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DC350 ACCELERATOR COMPLEX Distribution switchboard of building RShch380/220 V
S = 850 kVA
Sconsumed = 590 kVA
Channel 4
Channel 3 ShR3K
S = 220 kVA
ShR4K
269 Sconsumed = 480 kVA
Channel 5
S = 330 kVA
ShR5K
S = 40 kVA
20 kVA
200 kVA
20 kVA
310 kVA
40 kVA
Control cabinet
Power supply sources
Control cabinet
Power supply sources
Control cabinet
Room of power supply and control system
ShRKh
S = 140 kVA
ShRF
S = 120 kVA
30 kVA
30 kVA
40 kVA
40 kVA
40 kVA
50 kVA
30 kVA
Radioc hemical labora tory 2
Radioc hemical labora tory 2
Detector room
Workshop
Measurement center
Spectro metry
Workshop
Chemical laboratory
Physical laboratory
Fig. 21. Structural diagram of the power supply of experimental setups. Notation is the same as in Fig. 20.
DV
DV
DV
I circuit Cooled equipment DV
II circuit
RF
Power supply source
ECR
FC
FC
FC
DR
FC
Magnet
V/LC
HE
PII
P1 V2
V1
Fig. 22. Schematic diagram of the DC350 cooling system. PHYSICS OF PARTICLES AND NUCLEI LETTERS
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12:08
EMC 63.500 mV (2540.0 A) 50.65 kV
59.74 kV
Plus
14.73 kV
5.67 kV
5.31 kV
2.275 mA
0.358 mA
0.337 mA
B12
R
72.97 %
5.84 mm
A11 B11 A12
9.9 C
24.2 C
58.7 V 0.18 mA
0.127 kV
0288
W
0237
W
438 V 0.24 A
0.03 mA 2.743 V
57.02 mm
7.07 V 14.73 kV –0.5 V
0.44 A 21.06 mm
0.0 V 0.0 mA
Fig. 23. Accelerator control window.
automatic control system of the DC350 accelerator has the following functions: (i) it collects, processes, and presents online infor mation on the accelerator operation regime to the technological staff; (ii) it provides faultlessness of all systems of the accelerator, automatic emergency kill switch, and audio notification of the operator on accelerator oper ation; (iii) separate systems of the accelerator automati cally switch on and off; (iv) it logs and stores accelerator operation regimes; (v) it automatically determines the operation regimes for accelerator systems using stored values of acceleration regimes; (vi) it controls accelerator operation via an external information network. Structurally, the automatic control system of the DC350 is located in 20 cases, 11 of which are occu pied by the power supply system of the accelerator. All cases are controlled using unified SmartBox6 con trollers developed at the Laboratory of Nuclear Reac tions of the Joint Institute for Nuclear Research. All controllers are united via Ethernet. More detailed information on the equipment and its characteristics can be found at http://smartbox.jinr.ru. All control
cases and power supply sources are located in the direct neighborhood of the controlled equipment. The power supply sources were designed and devel oped at EVPU (NovaDubnica, Slovakia). The sources possess unified schemes, exchange protocol, and embodiment. Three computers are installed in the control panel. The basic computer offers communication with the peripheral equipment and all functions required for data base maintenance and storage. The second and third computers receive a data base from the first com puter via Ethernet and give two operators workspaces for the simultaneous control of several accelerator sys tems. The third computer is mobile and can execute the function of a local control panel for preventive and repair work at the accelerator. In this case it is con nected to the Ethernetoutlet in the accelerator hall. The accelerator parameters can be controlled using a keyboard, a mouse, and a panel of 8 encoders. Software tools of the automatic control system of accelerator complexes consist of the user’s application software and project development programs. The soft ware is created for realtime system QNX and SCADA FlexControl. A graphic window interface Photon is used for operation with QNX in graphic regime. The view of control windows for separate accelerator sub systems is shown in Fig. 23, as exemplified by the con trol window of a U400 accelerator.
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Table 5. Ion beam parameters Ions 7
Li1+ C 14 2+ N 16O2+ 16 3+ O 20 Ne3+ 20 Ne4+ 24Mg3+ 24 Mg4+ 24Mg5+ 27 3+ Al 27 4+ Al 27Al5+ 32S4+ 32 5+ S 32S6+ 40Ar4+ 40Ar5+ 40Ar6+ 40Ar8+ 48Ca5+ 48Ca6+ 48Ca7+ 48Ca8+ 48Ca9+ 48Ca10+ 58Fe7+ 58Fe9+ 58Fe11+ 58Fe13+ 64Ni7+ 64Ni9+ 64Ni11+ 64Ni13+ 84Kr9+ 84Kr10+ 84Kr11+ 84Kr12+ 84Kr13+ 132Xe14+ 132Xe15+ 132Xe16+ 132Xe17+ 132 18+ Xe 132Xe19+ 132Xe20+ 132Xe21+ 132Xe22+ 209Bi23+ 209Bi30+ 12 2+
Minimum ion energy, Maximum ion energy, Total ion energy, Ion source inten Extracted beam Extracted beam MeV/nucleon MeV/nucleon MeV/nucleon sity, particles μA intensity, particles μA power, W 4.67 6.37 4.68 3.59 8.05 5.16 9.16 3.59 6.37 9.94 3.00 5.04 7.85 3.59 5.60 8.06 2.95 3.59 5.17 9.16 2.95 3.59 5.17 6.37 8.06 9.94 3.35 5.53 8.24 11.49 2.95 4.54 6.78 9.44 2.94 3.26 3.94 4.69 5.49 2.95 2.97 3.37 3.81 4.27 4.75 5.27 5.81 6.37 2.95 4.73
6.82 9.29 6.83 5.24 11.75 7.54 12.00 5.24 9.29 12.00 4.14 7.35 11.46 5.24 8.17 11.75 3.36 5.24 7.54 12.00 3.64 5.24 7.54 9.30 11.75 12.00 4.89 8.07 12.00 12.00 4.01 6.63 9.88 12.00 3.85 4.75 5.75 6.84 8.02 3.78 4.33 4.93 5.56 6.23 6.94 7.69 8.47 9.29 4.06 6.90
PHYSICS OF PARTICLES AND NUCLEI LETTERS
47.7 111.5 95.6 83.8 188.0 150.7 240.0 125.7 223.0 288.0 111.8 198.5 309.4 167.7 261.5 376.0 134.2 209.6 301.6 480.0 174.7 251.5 361.9 446.4 564.0 576.0 283.6 468.1 696.0 696.0 256.6 424.3 632.3 768.0 323.4 399.3 482.8 574.6 673.6 498.3 571.8 650.4 773.9 822.4 916.1 1014.7 1118.3 1226.7 849.2 1442.5 Vol. 7
400 150 150 200 100 100 80 100 50 70 100 50 30 70 50 50 100 70 50 40 30 24 24 18 12 6 24 18 6 1.8 18 18 15 6 15 15 15 9 6 7.5 6 6 5 4 3 2.5 2 1.5 3 0.25 No. 4
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40 15 20 20 10 10 8 10 5 7 10 5 3 7 5 5 10 7 5 4 5 4 4 3 2 1 4 3 1 0.3 3 3 2.5 1 2.5 2.5 2.5 1.5 1 1.5 1 1 0.8 0.7 0.5 0.4 0.3 0.25 0.5 0.025
1910 1672 1912 1677 1880 1507 1920 1257 1115 2016 1118 992 928 1174 1308 1880 1342 1467 1508 1920 874 1006 1448 1339 1128 576 1134 1404 696 209 770 1273 1581 768 809 998 1207 862 674 747 572 650 587 576 458 406 335 307 425 36
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14. BASIC PARAMETERS OF ACCELERATED ION BEAMS The basic parameters of ion beams accelerated at DC350 cyclotron are given in Table 5.
3. G. G. Gulbekyan et al., “Axial Injection Channel of the DC350 Cyclotron,” in Proc. of the 18th Intern. Conf. on Cycl. and Their Appl., Giardini Naxos, Italy, Sept. 30– Oct. 5, 2007. 4. N. Kazarinov, “NonLinear Distortion of MultiCom ponent Heavy Ion Beam Emittance Caused by Space Charge Fields,” Rev. Sci. Instrum. 75, 1665 (2004).
REFERENCES 1. A. Efremov et al., “Status of the Ion Source DECRISSC,” Rev. Sci. Instrum. 77, 03A320 (2006). 2. V. V. Bekhterev et al., “The Project of the Supercon ducting ECR Ion Source DECRISSC2,” in Proc. of the 17th Intern. Workshop on ECR Ion Sources and Their Appl., IMP. Lanzhou, China, Sept. 17–21, 2006, High Energy Phys., Nucl. Phys. A, Ser. J. of the Chin. Phys. Soc. C 31 (SUppl. 1), 23–26 (2007).
5. N. Yu. Kazarinov and M. N. Sazonov, “Magnet Design and Beam Dynamics in Computed Fields for DC350 Cyclotron,” Part. Nucl. Lett. 5, 625–628 (2008). 6. I. Kalagin et al., “Beam Lines for Physical Experiments of DC350 Cyclotron,” in Proc. of the 18th Intern. Conf. on Cycl. and Their Appl., Giardini Naxos, Italy, Sept. 30–Oct. 5, 2007, p. 355.
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