Electrostatic and magnetic elements of the new extraction system for the isochronous cyclotron AIC-144
On the isochronous cyclotron AIC-144 the beam extraction is realized with the help of a new extraction system. As extraction system elements three electrostatic deflectors and three passive magnetic channels are used. The parameters and features for all elements are given. The particularities and de...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
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| Цитувати: | Electrostatic and magnetic elements of the new extraction system for the isochronous cyclotron AIC-144 / N.A. Morozov, E. Bakewicz, K. Daniel, H. Doruch, R. Taraszkiewicz // Вопросы атомной науки и техники. — 2001. — № 3. — С. 108-110. — Бібліогр.: 4 назв. — англ. |
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irk-123456789-792472015-03-31T03:02:39Z Electrostatic and magnetic elements of the new extraction system for the isochronous cyclotron AIC-144 Morozov, N.A. Bakewicz, E. Daniel, K. Doruch, H. Taraszkiewicz, R. On the isochronous cyclotron AIC-144 the beam extraction is realized with the help of a new extraction system. As extraction system elements three electrostatic deflectors and three passive magnetic channels are used. The parameters and features for all elements are given. The particularities and details of the constructive decisions applying under their realization are described. 2001 Article Electrostatic and magnetic elements of the new extraction system for the isochronous cyclotron AIC-144 / N.A. Morozov, E. Bakewicz, K. Daniel, H. Doruch, R. Taraszkiewicz // Вопросы атомной науки и техники. — 2001. — № 3. — С. 108-110. — Бібліогр.: 4 назв. — англ. 1562-6016 PACS numbers: 29.20.Hm http://dspace.nbuv.gov.ua/handle/123456789/79247 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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English |
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On the isochronous cyclotron AIC-144 the beam extraction is realized with the help of a new extraction system. As extraction system elements three electrostatic deflectors and three passive magnetic channels are used. The parameters and features for all elements are given. The particularities and details of the constructive decisions applying under their realization are described. |
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Article |
| author |
Morozov, N.A. Bakewicz, E. Daniel, K. Doruch, H. Taraszkiewicz, R. |
| spellingShingle |
Morozov, N.A. Bakewicz, E. Daniel, K. Doruch, H. Taraszkiewicz, R. Electrostatic and magnetic elements of the new extraction system for the isochronous cyclotron AIC-144 Вопросы атомной науки и техники |
| author_facet |
Morozov, N.A. Bakewicz, E. Daniel, K. Doruch, H. Taraszkiewicz, R. |
| author_sort |
Morozov, N.A. |
| title |
Electrostatic and magnetic elements of the new extraction system for the isochronous cyclotron AIC-144 |
| title_short |
Electrostatic and magnetic elements of the new extraction system for the isochronous cyclotron AIC-144 |
| title_full |
Electrostatic and magnetic elements of the new extraction system for the isochronous cyclotron AIC-144 |
| title_fullStr |
Electrostatic and magnetic elements of the new extraction system for the isochronous cyclotron AIC-144 |
| title_full_unstemmed |
Electrostatic and magnetic elements of the new extraction system for the isochronous cyclotron AIC-144 |
| title_sort |
electrostatic and magnetic elements of the new extraction system for the isochronous cyclotron aic-144 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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2001 |
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http://dspace.nbuv.gov.ua/handle/123456789/79247 |
| citation_txt |
Electrostatic and magnetic elements of the new extraction system for the isochronous cyclotron AIC-144 / N.A. Morozov, E. Bakewicz, K. Daniel, H. Doruch, R. Taraszkiewicz // Вопросы атомной науки и техники. — 2001. — № 3. — С. 108-110. — Бібліогр.: 4 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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2025-07-06T03:17:35Z |
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| fulltext |
ELECTROSTATIC AND MAGNETIC ELEMENTS OF THE NEW
EXTRACTION SYSTEM FOR THE ISOCHRONOUS
CYCLOTRON AIC-144
N.A. Morozov, E. Bakewicz1, K. Daniel1, H. Doruch1, R. Taraszkiewicz1
Joint Institute for Nuclear Research
Dubna, Moscow Region, 141980, Russia
E-mail: morozov@nusun.jinr.dubna.su
1Henryk Niewodniczanski Institute of Nuclear Physics
ul. Radzikowskiego 152, 31-342, Krakow, Poland
On the isochronous cyclotron AIC-144 the beam extraction is realized with the help of a new extraction system. As
extraction system elements three electrostatic deflectors and three passive magnetic channels are used. The parame-
ters and features for all elements are given. The particularities and details of the constructive decisions applying un-
der their realization are described.
PACS numbers: 29.20.Hm
1 INTRODUCTION
The AIC-144 isochronous cyclotron [1] designed
and constructed at the Institute of Nuclear Physics in
Krakow will be able to generate beams of protons and
deuterons. One of the principal goal of the new facility
is to extract the beams of protons and possibly,
deuterons (proton energy 60 MeV, deuteron energy 30
MeV) for proton radiotherapy and for horizontal and
vertical fast neutron beams [2].
It was extremely important to select the best and the
most efficient extraction system for the cyclotron [3, 4].
The problem of the effective beam extraction was found
difficult considering constrains of the existing cy-
clotron. The precession method for extraction was
agreed as the right one. One of the most important is-
sues was the control of the 1-st harmonic of the magnet-
ic field distortion due to the deflection system in the
area of the internal circulating beam. It was important to
measure the effect of such a magnetic field distortion
and to introduce the measured data into the computer
codes for beam dynamics calculations. Requirement to
have the realistic fringe field maps, including the field
inside of the magnetic channels, stimulated the neces-
sary measurements of the field. The means to correct the
possible field distortion due to the removal of ferromag-
netic material from the valley between sectors for instal-
lation of the new harmonic coils were foreseen. Opti-
mization of the various parameters of the proposed ex-
traction system, e.g. positions, field, gradients, etc…
were included into the upgrade program. It was useful to
organize a field modification in order to shift the posi-
tion of the coupling resonance to limit the axial blow-up
of the beam by including the corresponding valley
shims and other available means. The central region
structure has been investigated in details to obtain the
necessary beam quality in the pre-extraction region. The
non-linear effects inside extraction elements have been
taken into account to prevent deterioration of the beam
emittance. Matching of the extraction beam to the
downstream beam transport system acceptance has been
performed. Designing of the electrostatic channels was
done with special care.
Beam extraction experiments were carried out for
the proton of 35 MeV final energy. This regime has the
following parameters: main coil current of 169.2 A, op-
timal radio frequency of 19.995 MHz, a corresponding
isochronous magnetic field at the machine center was
13.250 kG, accelerating dee voltage was 45 kV. Inten-
sive simulation of particle motion and necessary align-
ments of the extraction system structure elements ac-
companied beam measurements.
The layout of the cyclotron chamber with the new
extraction system installed is given in Fig. 1.
Fig. 1. Cyclotron chamber with extraction system
layout. 1, 2, 3 - electrostatic deflector sections ESD-
1,2,3; 4, 5, 6 - magnetic channel sections MC-1,2,3;
7 - valley shim; 8 - harmonic coil; 9 - spiral shim;
10 - vacuum chamber; 11 – dee.
Table 1. Parameters of extraction system for proton en-
ergy 35.1 MeV
Element ϕ1
(°)
ϕ2
(°)
r1
(сm)
r2
(сm)
ESD-2 120 140 63.85 64.60
ESD-3 140 177 64.60 65.69
MC-1 183 205 65.66 65.99
MC-2 215 250 66.83 75.17
MC-3 273 283 88.37 98.33
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №3.
Серия: Ядерно-физические исследования (38), с. 108-110.
108
mailto:morozov@nusun.jinr.dubna.su
Element ∆В
(кG)
ε
(кV/сm)
dB/dx
(кG/сm)
dε/dx
(кV/сm2)
ESD-2 - 58.3 - 0.0
ESD-3 - 48.9 - -20.4
MC-1 -1.582 - 0.0 -
MC-2 -2.153 - 0.8 -
MC-3 0.0 - 1.0 -
In Table 1 the required parameters of the extraction
system that correspond to proton energy 35.1 MeV are
represented. The focusing gradients of electric and mag-
netic fields are used inside ESD-3, MC-2 and MC-3 in
order to compensate defocusing effect (in horizontal
plane) of the fringe magnetic field. The elements ESD-2
and MC-1 have a uniform field inside their working
apertures.
2 BEAM DEFLECTION, EXTRACTION SYS-
TEM ELEMENT REQUIREMENTS
The extraction system of the AIC-144 cyclotron con-
sists of 6 elements located inside the vacuum chamber
(see Fig. 1): 3 electrostatic deflectors and 3 magnetic
channels. They have the following notation and azimuth
position: ESD-1 – (98-117)°, ESD-2 – (120-140)°,
ESD-3 – (140-177)°, MC-1 – (183-205)°, MC-2 – (215-
250)°, MC-3 – (273-283)°. The 2-nd and 3-rd electro-
static deflectors are mounted on the same case and sup-
plied by one high- voltage unit. This set of elements is
proposed to be used for extraction of 60 MeV protons.
For extraction of 35 MeV protons the 1-st electrostatic
deflector can be removed from the vacuum chamber.
Possibilities of the rest elements are sufficient to extract
beam to the matching point. The matching point, where
beams of different type of particles and their energies
should be extracted to, has the coordinates ϕ=308°,
r=153 cm, and is situated just in front of the first ele-
ment of transport line.
3 STRUCTURAL ELEMENTS
3.1 Electrostatic deflectors
The electrostatic sections are shown in Fig. 2. The
septum parts of sections have water-cooling. The en-
trance part of the septum (thickness of 0.1 mm) is made
of tungsten. Use in a deflectors design of C-shaped
skeleton (stainless steel) allows to keep with a high ac-
curacy required septum curvature at thermal loading on
it due to losses of a beam up to several hundreds W.
The high-voltage electrode (titan) is not cooled by
water, his entrance part is protected from hit of particles
of a beam by special C-shaped diaphragm. Deflectors
have a remote drive for radial moving and changing of
the angle of an inclination in relation to a trajectory of a
beam.
The gap between septum and a high-voltage elec-
trode is adjusted within the limits of 4 – 15 mm without
removing vacuum in the chamber of a cyclotron, the
second kind of adjustment of a gap can provide its non-
uniformity within the limits of 10 mm along the trajec-
tory of a beam. Preliminary training of sections will be
carried out by a high voltage within 12 hours. For the
extraction of protons with the energy 35 MeV between a
septum and a high-voltage electrode of the section
ESD-2, 3 the gap of 5.5 mm at an entrance and 6.5 mm
at an exit of the section were established, a working
voltage was 45 kV (the calculation voltage was 40 kV).
3.2 Magnetic channels
The system of magnetic channels consists of three
channels MC-1, 2 and 3. The design of МС-2 is shown
in Fig. 3.
By means of the channel MC-1 a homogeneous de-
crease of a magnetic field by a value of ~0.18 T is car-
ried out by means of steel plates with the cross sizes
2.5 × 30 mm. In the magnetic channel MC-2 by means
of plates with the sizes (2.5-5) × 50 mm decrease of a
magnetic field by a value of 0.18 - 0.22 T and radial fo-
cussing of a beam with a gradient 8 T/m are carried out.
Additional steel plates in channels MC-1, 2 are placed
in the aluminum C - shaped case and carry out the shim-
ming of the magnetic field distortion brought by the
channel in the area of the accelerated beam (the value of
an average magnetic field distortion and the first har-
monic is shimmed up to several Gs).
The magnetic channel MC-3 at the initial stage was
designed as electromagnetic quadruple lens with the di-
ameter of the aperture 30 mm which can provide a beam
focusing in a radial direction with a gradient up to 20
T/m at a maximum level of its coil power dissipation of
1.9 kW. In area of accelerated beam the channel MC-3
creates the field perturbation not exceeding several Gs
(for average field and the first harmonic). At the second
stage the MC-3 was designed as a passive 3- ferromag-
netic bar channel. All magnetic channels have remote
adjustment of their radial position in the chamber of the
cyclotron, the channel MC-3 has also additional adjust-
ment of its angular position.
Fig. 2. Electrostatic deflector ESD-2-3, top view.
109
Fig. 3. Magnetic channel MC-2, entrance side.
3.3 Coils for the 1-st harmonic shaping
The value of amplitude and character of phase de-
pendence of the magnetic field first harmonic near the
radius R~60 cm are the parameters determining the
characteristics of the beam turn separation enhancement
in the electrostatic deflector mouth. The shaping of re-
quired characteristics of the magnetic field first harmon-
ic (В1=2 Gs, ϕ1 =0 - the phase is directed along the dee
axis) was carried out by means of new cyclotron har-
monic coils.
4 EXTRACTION EFFICIENCY
Commissioning of the extraction system has been
done as follows:
• measurement of the radial gain enhancement with-
out extraction system inside the vacuum chamber;
• the same but at presence of ESD-2, 3 at their work-
ing position in order to measure probable particle
losses on the outer side of the septum;
• pass of the beam through ESD-2, 3, measurement
of the particle losses inside them;
• step by step installation of the magnetic channels
MC-1, 2, 3 together with corresponding tuning of
the radial gain enhancement and measurement of
the beam transport efficiency on each step.
We have observed a very high efficiency (∼85%) of
the beam deflection at the exit of ESD-3 when no mag-
netic channels had been installed inside vacuum cham-
ber. Installation of the magnetic channels causes the ne-
cessity of additional efforts for 1-st harmonic compen-
sation in order to improve the process of radial gain en-
hancement. This procedure was not very long. As a rule,
1-2 hours was enough in order to obtain extracted beam
with efficiency no lower than 50%. No particle losses
have been detected inside the magnetic channels.
After the accurate adjustment of the extraction sys-
tem parameters (mainly careful control of the 1-st har-
monic of magnetic field and position of ESD-2, 3) we
have increased the extraction efficiency for 35 MeV
protons up to the calculation value of 70%.
REFERENCES
1. J.A.Schwabe et al. Automatic Isochronous Cy-
clotron AIC-144 // Proceedings of the International
Seminar on Isochronous Cyclotron Technique.
Krakow, Poland, November 13-18, 1978, p. 197,
IFJ Report N 1069/PL.
2. M.Waligorski, P.Olko. // Proc of International
Workshop on the Hadron Radiotherapy in Krakow
– Beam Extraction for Cancer Radiotherapy.
Krakow, December 2, 1996.
3. O.N.Borisov et al. Feasibility Study of the Beam
Extraction from the AIC-144 Cyclotron // JINR,
E9-96-492, Dubna, 1996. European Cyclotron
Progress Meeting, ECPM XXXI, Groningen, 18-20
September 1997, Abstracts, p. 24.
4. O.N.Borisov et al. New Beam Extraction System
for the AIC-144 Cyclotron // JINR, E9-98-130,
Dubna, 1998. Proc. of the 15th Int. Conf. On Cycl.
And their Appl., Caen, France, 14-19 June, 1998,
Institute of Physics Publishing, Bristol and
Philadelphia, p. 528.
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