Development of the new pre-stripping section for LUMZI
The investigations have been performed on the development of a multipurpose complex based on the linear heavy ion accelerator for high-intense light ion beam production. The investigations were carried out with theoretical and experimental methods. As a result physical prerequisites were developed f...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
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| Цитувати: | Development of the new pre-stripping section for LUMZI / V.A. Bomko, A.F. Dyachenko, B.V. Zajtzev, A.F. Kobets, Z.E. Ptukhina, B.I. Rudyak, V.V. Zhuk // Вопросы атомной науки и техники. — 2001. — № 3. — С. 128-130. — Бібліогр.: 5 назв. — англ. |
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irk-123456789-792542015-03-31T03:02:50Z Development of the new pre-stripping section for LUMZI Bomko, V.A. Dyachenko, A.F. Zajtzev, B.V. Kobets, A.F. Ptukhina, Z.E. Rudyak, B.I. Zhuk, V.V. The investigations have been performed on the development of a multipurpose complex based on the linear heavy ion accelerator for high-intense light ion beam production. The investigations were carried out with theoretical and experimental methods. As a result physical prerequisites were developed for creation of the pre-stripping section (POS-4) which enables acceleration of high-current light ion beams with the average current of 1-0.5 mA. 2001 Article Development of the new pre-stripping section for LUMZI / V.A. Bomko, A.F. Dyachenko, B.V. Zajtzev, A.F. Kobets, Z.E. Ptukhina, B.I. Rudyak, V.V. Zhuk // Вопросы атомной науки и техники. — 2001. — № 3. — С. 128-130. — Бібліогр.: 5 назв. — англ. 1562-6016 PACS numbers: 29.17.+w http://dspace.nbuv.gov.ua/handle/123456789/79254 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
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English |
| description |
The investigations have been performed on the development of a multipurpose complex based on the linear heavy ion accelerator for high-intense light ion beam production. The investigations were carried out with theoretical and experimental methods. As a result physical prerequisites were developed for creation of the pre-stripping section (POS-4) which enables acceleration of high-current light ion beams with the average current of 1-0.5 mA. |
| format |
Article |
| author |
Bomko, V.A. Dyachenko, A.F. Zajtzev, B.V. Kobets, A.F. Ptukhina, Z.E. Rudyak, B.I. Zhuk, V.V. |
| spellingShingle |
Bomko, V.A. Dyachenko, A.F. Zajtzev, B.V. Kobets, A.F. Ptukhina, Z.E. Rudyak, B.I. Zhuk, V.V. Development of the new pre-stripping section for LUMZI Вопросы атомной науки и техники |
| author_facet |
Bomko, V.A. Dyachenko, A.F. Zajtzev, B.V. Kobets, A.F. Ptukhina, Z.E. Rudyak, B.I. Zhuk, V.V. |
| author_sort |
Bomko, V.A. |
| title |
Development of the new pre-stripping section for LUMZI |
| title_short |
Development of the new pre-stripping section for LUMZI |
| title_full |
Development of the new pre-stripping section for LUMZI |
| title_fullStr |
Development of the new pre-stripping section for LUMZI |
| title_full_unstemmed |
Development of the new pre-stripping section for LUMZI |
| title_sort |
development of the new pre-stripping section for lumzi |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2001 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/79254 |
| citation_txt |
Development of the new pre-stripping section for LUMZI / V.A. Bomko, A.F. Dyachenko, B.V. Zajtzev, A.F. Kobets, Z.E. Ptukhina, B.I. Rudyak, V.V. Zhuk // Вопросы атомной науки и техники. — 2001. — № 3. — С. 128-130. — Бібліогр.: 5 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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2025-07-06T03:17:52Z |
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2025-07-06T03:17:52Z |
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| fulltext |
DEVELOPMENT OF THE NEW PRE-STRIPPING SECTION FOR LUMZI
V.A. Bomko, A.F. Dyachenko, B.V. Zajtzev, A.F. Kobets,
Z.E. Ptukhina, B.I. Rudyak, V.V. Zhuk
NSC “Kharkov Insitute of Physics and Technology”
1 Akademicheskaja Str., Kharkov, 61108, Ukraine
kobets@kipt.kharkov.ua
The investigations have been performed on the development of a multipurpose complex based on the linear heavy
ion accelerator for high-intense light ion beam production. The investigations were carried out with theoretical and
experimental methods. As a result physical prerequisites were developed for creation of the pre-stripping section
(POS-4) which enables acceleration of high-current light ion beams with the average current of 1-0.5 mA.
PACS numbers: 29.17.+w
The main task for the linear multicharged ion accel-
erator (LUMZI, at the NSC KIPT) was fundamental in-
vestigations in the field of nuclear physics and radiation
material technology. After being constructed it under-
went a number of improvements, and in 1989 its up-
grade was completed on the basis of an efficient accel-
erating structure of the interdigital type excited on the
H111 wave [1]. Some other systems were updated ac-
cording to the latest achievements in RF power produc-
tion, multicharge ion sources, high-voltage equipment,
and beam control and diagnostic systems.
The LUMZI consists of two sections - a pre-strip-
ping section (POS) and post-stripping one (OS) rated for
the energy of 0.975 and 8.5 MeV/nucleon, respectively.
The average beam intensity at the output of the sections
is (1012 - 1010) and (1011 - 109) particles/s for 14N, 20Ne,
40Ar, and others. The POS section is designated for ac-
celeration of ions of arbitrary kinds with a mass-to-
charge ratio of A/q ≤ 15, and the OS - for A/q ≤ 5.
The latest events have demanded a conversion of the
accelerator to solving new fundamental and applied
problems. Among them the most promising are: track
membrane production, radionuclide production, light
ion beams (protons, α-particles) accelerated to energies
of 8.5 MeV/nucleon and with average current of
1 - 0.5 mA. It will enable to produce rather intense neu-
tron beams (1012 - 1014) nucleon/s, and thus to give a
possibility to carry out investigations in neutron physics,
nuclear engineering and transmutation of nuclear waste,
medicine (boron neutron capture therapy). The LUMZI
features allow to solve these problems effectively. How-
ever, the requirements on heavy ion beams are different
for different tasks. For track membrane production ions
with a mass as high as possible are required, and for ra-
dionuclide production requires light ions (protons,
deuterons, helium ions (3He, 4He) with an average cur-
rent as high as possible (from 100 to 1000 µA). It is
practically impossible to combine these requirements
for a single accelerator. Here the pre-stripping section is
a bottleneck.
The pre-stripping section rated for acceleration of
ions with a mass-to-charge ratio of A/q = 4 (POS-4)
should be mounted alongside the existing POS-15 sec-
tion with parallel beam transfer to the input of the main
LUMZI section. The reduction in A/q from 15 to 4 will
allow to reduce the pulsed RF power supply of the ac-
celerator and to increase the average beam current. That
will enable acceleration of light ions (p, d, 3He, 4He).
Therefore, a small cavity will be necessary for accelera-
tion of these particles from energy of 30keV/nucleon to
energy of 1MeV/nucleon. This beam (after 3He and 4He
stripping) will be injected in the existing post-stripping
section by parallel transfer and will be accelerated to
8.5 MeV/nucleon. Therefore there is no principal limita-
tions on the acceleration of protons to the full energy of
8.5 MeV, deuterons - to 17 MeV, 3He – to 26MeV, and
4He - to 34MeV. At the same time reduction of the A/q
parameter from 5 to 1 (for protons) and to 2 (for deuteri-
um and helium) will allow the post-stripping section op-
eration in the facilitated mode. The level of RF power
for the proton acceleration will be 25 times lower than
the present one, and for deuterium and helium - 6.25
times lower. This will enable to increase considerably
the time duty factor (the pulse repetition and pulse dura-
tion) that would enable obtaining the indicated average
beam current.
The interdigital accelerating structure forms a basis
of the pre-stripping section. Operating experience on
this structure has been accumulated with construction of
the pre-stripping and main sections of LUMZI [2, 3].
The accelerating structure of interdigital type with a uni-
form distribution of the accelerating field in gaps be-
tween the drift tubes provides the rate of acceleration of
3-3.5MeV/m. Thus at the length of 1.3 m it is possible
to accelerate ions with A/q = 4 with average accelerat-
ing field gradients in the accelerating gaps of 80 kV/cm.
The accelerating structure of interdigital type excited
at the H wave differs from the unloaded cylindrical cav-
ity excited on the wave with a transverse electric field
component in a considerable drop in the eigenfrequen-
cy. Dependently on the load nature the eigenfrequency
of the loaded cavity decreases in 3 - 4 times. Such a
very useful phenomenon allows to reduce at the same
extent the transverse sizes or to increase the operational
wavelength for acceleration of the heavy ions.
The main requirement for linear acceleration is the
fulfillment of the condition of synchronism of the aac-
celerated ion movement in the RF field by increasing
the lengths of the accelerating gaps proportionally to in-
crease in velocity of particles travelling through the
cells. However, the irregularity of the sizes of the accel-
erating structure elements causes deterioration of the
uniformity in accelerating field distribution and changes
of operational wave frequency. Therefore the change of
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №3.
Серия: Ядерно-физические исследования (38), с. 128-130.
128
longitudinal cell dimensions implies the necessity of the
appropriate adjustment at the cost of the change of
transverse dimensions of the accelerating structure ele-
ments (the cavity, drift tubes) or at the cost of auxiliary
adjusting devices.
The choice of the operational wavelength was made
from the assumption that for excluding the loss of parti-
cle in the main section with their capture into accelera-
tion, the length of the main section should be equal or
multiple of the wavelength. From the considerations on
the simplicity of the compact accelerator structure and
unification of the RF equipment we decided that the op-
erational frequency of the pre-stripping section should
be equal to the operational frequency of the main sec-
tion, 47.2 MHz.
The calculations of the accelerating section and
beam dynamics were carried out for the new version of
the simultaneous radial and phase stability of the bunch-
es of accelerated particles, namely alternating phase fo-
cusing with a moving bunch center [4, 5]. Its main pa-
rameters are presented in the Table I.
Table I
Parameters of the POS-4 accelerator
Ion energy at the input, keV 30
Ion energy at the output, keV 975
Mass-to-charge ratio, A/q 4
Operational frequency, MHz 47.2
Electric field gradient in gaps, MV/m 8.0
Length of the accelerating structure, m 1.3
Diameter of the accelerating structure, m 0.7
Drift tube number 16
Drift tube aperture, mm 16-20
Synchronous phase of the bunching sec-
tion, grad
-40
Synchronous phase of the focusing sec-
tion, grad
+45
Number of bunching sections 4
Number of focusing sections 3
Acceleration rate, MeV/m 3.0
Longitudinal capture, grad 120
Radial acceptance, mm.mrad 3100
Normalized radial acceptance, π.mm.m-
rad
2.4
Time duty factor, % 2.5
As one can see from the Table I that the accelerating
structure based on the alternating phase focusing with
the moving bunch center has small longitudinal and
transverse sizes, is simple in construction, and possesses
a high longitudinal capture. The radial acceptance is at
the level typical for the quadruple focusing with essen-
tial simplicity of drift tubes. The application in the
POS-4 of interdigital accelerating structure reduces con-
siderably the RF power consumption.
Using the results of the calculations of the longitudi-
nal sizes a model was manufactured for determination
of electrodynamic characteristics of the cavity, adjust-
ment to the frequency, and formation of the uniform
electric field distribution along the structure (Fig. 1).
Fig. 1. The model of the LUMZI pre-stripping sec-
tion (photograph).
The scale of the model was 1:2 as the most optimal
from the viewpoint of reliability of the results and con-
structional potentials. The largest difficulty was that be-
forehand it is practically impossible to determine to suf-
ficient accuracy the cavity diameter. In this connection
the goal was achieved by the "successive approxima-
tions". We had to manufacture 3 cavities before the
specified resonance frequency of 94.4 MHz was
achieved with the uniform field distribution.
The construction of the accelerating structure is sim-
ilar to that applied at the pre-stripping and main sections
of the linear multicharge ion accelerator LUMZI. The
drift tubes are connected in turns with conducting stems
to diametrically opposite sides of the cavity forming the
interdigital system (Fig. 2).
Fig. 2. The construction of the POS LUMZI section.
The arrangement and the number of the adjusting
resonance elements were determined. At the output end
of the structure two end resonance elements are formed
from one even (16) and one odd (15) drift tubes: these
drift tubes are mounted on the longitudinal carrying ele-
ment which in its turn is fastened at the side cavity sur-
face forming the end quarterwave resonance adjusting
element (Fig. 2). With shifting the pistons placed be-
tween cavity walls and longitudinal carrying elements
we changed the electric field distribution. The electric
field strength on the cavity axis was determined on the
perturbation contributions by a metallic body to the gaps
of the accelerating structure.
The previous measurements have shown that the
field is concentrated in the initial part of the cavity.
Varying the outer diameter of the drift tubes the electric
field extent is spread over the total cavity length, and
with following changes of the slit depth of the end ele-
ments the specified uniform distribution of the electric
129
field strength along the accelerating structure field with
the operational wavelength of f1 = 94.4 MHz for the H111
wave has been obtained. Some variations in the field
distribution is due to the fact that the model is not suited
to rather precise adjustment of the drift tubes. In the ac-
tual structure where the lengths of the gaps will corre-
spond exactly to requirements of accuracy these devia-
tions will disappear. The resonance frequency of oscilla-
tions of the H112 type is f2 = 104.7 MHz, and for H113
mode - f3 = 126.8 MHz, that is the structure possesses
rather good dispersion.
Fig. 3. The final field distribution in the gaps of the
POS LUMZI model.
To accelerate heavy ions with A/q = 4 from 30 keV
to 0.975 MeV it is necessary to have 16 drift tubes and
two half-tubes with the outer diameter from 32 to
70 mm. The lengths of accelerating gaps and drift tubes
vary from 13 mm to 87 mm, drift tube aperture varies
by steps from 16 mm for the first tubes and to 20 mm
for the following ones. The cavity diameter is 750 mm
and the length is 1298 mm.
The Q-factor and shunt impedance measured after
adjustment with the formed uniform distribution of the
accelerating field, correspond to those of the full-scale
POS-4 - 15000 and 150 MOhm/m. Thus, to excite the
electric field of 80 kV/cm in the gaps between drift
tubes, the RF generator power of 150 kW is necessary.
CONCLUSIONS
From the results of experimental investigations on
the models, the geometric sizes of the elements of the
interdigital accelerating structure designed for the
LUMZI pre-stripping section for acceleration of the
high-intense light ion beams were obtained. The con-
structing of the adjusting elements of the accelerating
structure and its adjusting to the operational frequency
were performed, the uniform distribution of the acceler-
ating field was formed, RF parameters, Q-factor and
shunt impedance were optimized. The required RF pow-
er is evaluated.
The work done shows that the reduction in the ion
mass-to-charge ratio allows to increase the time duty
factor by an order of magnitude and thus to bring the
average current of helium and proton beam to 1 and
0.5 mA, respectively. This value exceeds considerably
the output beam current of the cyclotrons used for ra-
dionuclide production all over the world.
The development of a new version of the pre-strip-
ping LUMZI section for a light ion intense beam, POS-
4, enables the creation of the general-purpose complex
for efficient production of diversified, radionuclides
which are necessary for medicine and high-tech indus-
try, and to carry out investigations in neutron physics,
electronuclear engineering, nuclear waste transmutation,
medicine (boron neutron capture therapy).
REFERENCES
1. V.A.Bomko, A.P.Kobets, Yu.P.Mazalov,
B.I.Rudyak // Ukrainian Physics Journal. 1998,
v. 43, N 9, p. 1144.
2. V.A.Bomko, A.P.Kobets, Yu.P.Mazalov,
B.I.Rudyak // Review of Scientific Instruments.
1998, v. 69, N 10, p. 378.
3. V.A.Bomko, A.F.Dyachenko, A.P.Kobets et al. //
Problems of Atomic Science and Technology. Is-
sue: Nuclear-Physics Research (6). 1989, p. 23-27
(in Russian).
4. V.A.Bomko, Yu.P.Mazalov, Yu.V.Meleshkova //
Proc. of XV Meeting on Charged Particle Acelera-
tors, Protvino, 1996, v. 2, p. 50.
5. V.A.Bomko, N.P.Diky, A.P.Kobets et al. // Prob-
lems of Atomic Science and Technology. Issue: Nu-
clear-Physics Research (35). 1999, N 4, p. 20-22.
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