Stand adjusting of a new pre-stripping section MILAC
Results of tuning of irregular interdigital accelerating structure with focusing by radiofrequency field, installation in new prestripping section PSS-4 of the multi charged ions linear accelerator (MILAC), on the experimental stand are presented. The effective inductance-capacitor tuning devices...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
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| Zitieren: | Stand adjusting of a new pre-stripping section MILAC / V.A. Bomko, A.F. Dyachenko, B.V. Zaytsev, A.F. Kobets, J.V. Ivakhno, V.I. Misjura // Вопросы атомной науки и техники. — 2008. — № 3. — С. 60-63. — Бібліогр.: 3 назв. — англ. |
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irk-123456789-1111932017-01-09T03:04:45Z Stand adjusting of a new pre-stripping section MILAC Bomko, V.A. Dyachenko, A.F. Zaytsev, B.V. Kobets, A.F. Ivakhno, J.V. Misjura, V.I. Физика и техника ускорителей Results of tuning of irregular interdigital accelerating structure with focusing by radiofrequency field, installation in new prestripping section PSS-4 of the multi charged ions linear accelerator (MILAC), on the experimental stand are presented. The effective inductance-capacitor tuning devices (contrivance) as rods located on the drift tube side, opposite to their holders are developed. Наведено результати настроювання на експериментальному стенді нерегулярної зустрічно-штиревої прискорюючої структури з фокусуванням високочастотним полем, впровадженої в новій передобдирковій секції ПОС-4 лінійного прискорювача багатозарядних іонів (ЛУМЗІ). Розроблено ефективні настроювальні пристрої у вигляді стерженьків, розташованих на боковій поверхні трубок дрейфу протилежно їх підвіскам. Приведены результаты настройки на экспериментальном стенде нерегулярной встречно-штыревой ускоряющей структуры с фокусировкой высокочастотным полем, внедренной в новой предобдирочной секции ПОС-4 линейного ускорителя многозарядных ионов (ЛУМЗИ). Разработаны эффективные настроечные устройства в виде стерженьков, расположенных на боковой поверхности трубок дрейфа противоположно их подвескам. 2008 Article Stand adjusting of a new pre-stripping section MILAC / V.A. Bomko, A.F. Dyachenko, B.V. Zaytsev, A.F. Kobets, J.V. Ivakhno, V.I. Misjura // Вопросы атомной науки и техники. — 2008. — № 3. — С. 60-63. — Бібліогр.: 3 назв. — англ. 1562-6016 PACS: 27.17. +w http://dspace.nbuv.gov.ua/handle/123456789/111193 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Физика и техника ускорителей Физика и техника ускорителей |
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Физика и техника ускорителей Физика и техника ускорителей Bomko, V.A. Dyachenko, A.F. Zaytsev, B.V. Kobets, A.F. Ivakhno, J.V. Misjura, V.I. Stand adjusting of a new pre-stripping section MILAC Вопросы атомной науки и техники |
| description |
Results of tuning of irregular interdigital accelerating structure with focusing by radiofrequency field, installation
in new prestripping section PSS-4 of the multi charged ions linear accelerator (MILAC), on the experimental
stand are presented. The effective inductance-capacitor tuning devices (contrivance) as rods located on the drift tube
side, opposite to their holders are developed. |
| format |
Article |
| author |
Bomko, V.A. Dyachenko, A.F. Zaytsev, B.V. Kobets, A.F. Ivakhno, J.V. Misjura, V.I. |
| author_facet |
Bomko, V.A. Dyachenko, A.F. Zaytsev, B.V. Kobets, A.F. Ivakhno, J.V. Misjura, V.I. |
| author_sort |
Bomko, V.A. |
| title |
Stand adjusting of a new pre-stripping section MILAC |
| title_short |
Stand adjusting of a new pre-stripping section MILAC |
| title_full |
Stand adjusting of a new pre-stripping section MILAC |
| title_fullStr |
Stand adjusting of a new pre-stripping section MILAC |
| title_full_unstemmed |
Stand adjusting of a new pre-stripping section MILAC |
| title_sort |
stand adjusting of a new pre-stripping section milac |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2008 |
| topic_facet |
Физика и техника ускорителей |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/111193 |
| citation_txt |
Stand adjusting of a new pre-stripping section MILAC / V.A. Bomko, A.F. Dyachenko, B.V. Zaytsev, A.F. Kobets, J.V. Ivakhno, V.I. Misjura // Вопросы атомной науки и техники. — 2008. — № 3. — С. 60-63. — Бібліогр.: 3 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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| first_indexed |
2025-07-08T01:46:58Z |
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| fulltext |
____________________________________________________________
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2008. № 3.
Series: Nuclear Physics Investigations (49), p.60-63.
60
STAND ADJUSTING OF A NEW PRE-STRIPPING SECTION MILAC
V. A. Bomko, A. F. Dyachenko, B. V. Zaytsev, A. F. Kobets, Je. V. Ivakhno,V. I. Misjura
NSC KIPT, Kharkov, Ukraine
E-mail: bomko@kipt.kharkov.ua
Results of tuning of irregular interdigital accelerating structure with focusing by radiofrequency field, installa-
tion in new prestripping section PSS-4 of the multi charged ions linear accelerator (MILAC), on the experimental
stand are presented. The effective inductance-capacitor tuning devices (contrivance) as rods located on the drift tube
side, opposite to their holders are developed.
PACS: 27.17. +w
1. DESIGN FEATURES THE
ACCELERATING STRUCTURE PSS-4
The results on development and construction of the
prestripping section (A/q = 4) for multi charge ion linear
accelerator (MILAC) designed for acceleration of He+
ion beam from 30 keV/u to 975 keV/u are presented. In
the accelerating interdigital IH structure He+ ion beam
were accelerated using the method of alternating phase
focusing with stepped changing the synchronous phase
along the focusing period [1]. Efficiency of this method
depends strongly on configuration of each focusing pe-
riod. The structure of the focusing period in the con-
struction being discussed contains a number of cells
where the synchronous phase changes discretely from
the cells with negative (bunching) phases passing the
cells having the phase smaller in absolute value through
ϕs = 0 to the zone of positive (focusing) phases and at
last with transition to the zone of negative phases. Such
choice of synchronous phases provides the capture of
high current ion beam being injected in the phase angle
of 120° and maintenance its radial and phase stability
along the accelerating structure.
The accelerating structure in which such method of
radial and phase focusing of the ion beam bunches is
used, is very non-uniform. The requirement of the syn-
chronous phase transfer in a wide range results to that
the length трубок drift on each focusing period changes
in some times. For this reason tuning of cells of such
accelerating structure represents significant difficulties.
To this it is necessary to add, that accelerating structure
PSS-4 is designed for low entrance energy of ions
(30 МeV on a nucleon) and rather high pulse current
(12 мА). To provide the maximal capture of particles in
a mode of steady radial and longitudinal movement,
distribution of an accelerating field in an initial part of
structure has been solved to make increasing from a cell
to a cell.
2. ADJUSTMENT OF THE ACCELERATING
STRUCTURE PSS-4
Interdigital structure represents the large capacitor
and inductive loading of the resonator, that results to
significant decreasing (almost in 3 times) of the Н111-
mode resonant frequency. This important feature inter-
digital type accelerating structure has favourable an
effect for the cross sizes of the resonator, that is espe-
cially important at creation of heavy ions accelerators,
since their rather low speed requires the appropriate
increase of a operating wave length. Other important
feature of the interdigital type accelerating structure is
the ability to retain a π-mode regime, which allows a 2-
time increase of accelerating rate in comparison with
mode of operations on 2π-mode regime, which is pecu-
liar to structure Alwarez, where Е010 – mode is used.
Such result can be achieved only in the case when exe-
cute tuning ensuring uniform distribution of an acceler-
ating field along cells of accelerating structure.
The problem of adjustment accelerating structure
PSS-4 was especially difficult in connection with the
non-uniform of lengths of cells mention above in struc-
ture of the focusing periods and increasing character of
distribution of an accelerating field along the accelera-
tor. Therefore it was required to apply a combination of
various tuning methods.
Calculations of constructive and electrodynamics
characteristics were carried out in 3D version. The pro-
cedure of «manual control» was used which means that
the geometrical sizes were sequentially changed for
obtaining the required values of necessary characteris-
tics. In the process of optimization parameters for the
elements of the structure (cavity diameter, cavity shape,
the drift tube diameters, diameters of the drift tube hold-
ers) were adjusted to the required values.
Table 1. Main parameters of the PSS-4
Input ion energy 30 keV/u
Output ion energy 975 keV/u
Operating frequency 47.2 MHz
Growing accelerating field 85 kV/cm
Total acceleration rate 1.6 MeV/m
Cavity length 2395 mm
Number of accelerating cells 32
Cavity diameter 107.5 cm
Pulsed current of accelerated ions 12 mA
Angle of beam capture 120°
Q-factor of the cavity 12000
Shunt impedance 50 MΩ/m
Pulse repetition rate 12.5 Hz
In the process of tuning the end resonance device
were used which represent quarter wave ending reso-
61
nant device (inducer); on the side of the inducer facing
the side wall of the cavity a control piston is placed
which can move in longitudinal direction. Such systems
are installed on the input and output ends of the cavity.
The results of calculations of geometrical and elec-
tro-dynamical characteristics are presented in the table 1
and schematic view of the PSS-4 accelerating structure
represented on Fig.1.
Fig.1. Schematic view of the PSS-4 accelerating struc-
ture
External view of the collected resonator with system
of cooling is presented on Fig.1, and accelerating struc-
ture after initial assembly – on Fig.2.
Fig.2. External view of the collected resonator after
final technological assembly
Fig.3. Accelerating structure after initial assembly
As adjusting elements the end resonant tuning ele-
ments developed earlier (ERTE) [2], established on the
entrance and exit ends of accelerating structure (Fig.4
and Figs.3,5) and two pairs additional current-carrying
stems of the drift tubes, established only on its entrance
end (Fig.3,5) were used. The physical reasoning of this
method of adjustment of the interdigital accelerating
structure of basic section MILAC is described in work
[3].
Fig.4. The end resonant tuning element
on the exit end accelerating structure
Fig5. The end resonant tuning element and additional
stems on the entrance end accelerating structure
3. NEW TUNING ARRANGEMENTS
In the process of manufacturing and assembling the
elements of the accelerating structure it appeared that
the frequency is higher than the operating frequency by
900 kHz though electric field distribution was close to
the calculated one. Therefore development of additional
tuning devices was necessary acting on the electric
field. The investigations were carried through calcula-
tions.
We develop variant extreme simple and effective
method of inductance-capacitor tuning. The effect such
tuning system on electrical field decrease own fre-
quency of the resonator, that allows once more to reduce
a diameter of the resonator and to generate practically
uniform accelerating field ensuring the highest rate of
acceleration. In this case tuners represent a simple de-
sign as rods, located on the drift tube from the side op-
posite to their holders. They form thus, together with
adjacent of drift tube holders additional capacitive and
inductive loading, that causes the appropriate decreasing
of the own cell frequencies and local increase of an
electrical field in gaps between drift tubes. In the pre-
sent statement such elements of inductance-capacitor
loading are named «contrivance».
62
Their quantity, the sizes (length and diameter) and
corners of deviation from a plane which are passing
through the basic stems of fastening drift tube, were
preliminary defined by numerical simulations, and then
checked experimentally at the stand. «Contrivances»
have proved as the effective element of tuning locally
influencing value of an electric field in the nearest gaps
and lowering resonant frequency without noticeable
worsening of electrodynamic characteristics of resonant
system. On Fig.6 and Fig.7 the constructive decision of
fastening «contrivances» on drift tubes is shown, and in
the table 2 their sizes and angle of a deviation from a
plane which are passing through the basic stems are
resulted.
Table 2. Constructive characteristics and disposition of
the «contrivances» on drift tubes
№ Number
drift tube
Diameter,
mm
Length,
mm
Angle of a
deviation,
degree
1 16 10 30 0
2 18 15 35 30
3 21 15 33 0
4 23 20 27 0
5 25 10 40 0
6 26 26 30 0
7 28 26 45 45
8 30 26 45 45
9 31 26 70 45
Fig.6. «Contrivance», established on 16 and 18 drift
tubes
Fig.7. «Contrivance», established on 26, 28 and 30 drift
tubes
As a result of complex influence of all elements of
tuning the set distribution of an electric field in structure
on operating frequency 47.2 MHz is received. On Fig.8
character of change of an electric field is traced (in rela-
tive units) on an axis of the resonator, received at nu-
merical simulations geometry of accelerating structure.
Points note values which are set by calculation of dy-
namics of the accelerated bunch, and by asterisks – ex-
perimental values. Deviations of experimental values of
electric fields in gaps from calculated values are in ac-
ceptable limits.
Fig.8. Distribution of the electric field in structure on
operating frequency of 47.2 MHz (calculation field set
by numerical simulations, • – set by dynamics of
a bunch, ∗ – experimental)
On the Fig.9 the accelerating structure after carrying
out of final adjustment for the set frequency, and on
Fig.10 – process of mounting of the resonator in a va-
cuum tank is shown.
Fig.9. Accelerating structure after final tuning
Fig.10. Mounting of the resonator in a vacuum tank
63
REFERENCES
1. V.A. Bomko, A.F. Dyachenko, B.V. Zajtsev,
A.F. Kobets, Ye.V. Ivakhno, Z.E. Ptukhina,
S.S. Tishkin, E.D. Marynina. Tuning irregular inter-
digital accelerating structure with RF field focusing
// Problems of Atomic Science and Technology. Se-
ries «Nuclear Physics Investigations» (47). 2006,
№3, p.78-80.
2. V.A. Bomko, A. F. Dyachenko, A. F. Kobets,
Yu. P. Mazalov, B. I. Rudyak. Smooth variation of
ion energy in the interdigital accelerating H-
structure // Nuclear Instrumens & Methods in
Physics Research. 1998, A 406, p.1-5.
3. V.A. Bomko, N.I. Demchuk, A.F. Dyachenko,
A.F. Kobets, Yu.P. Mazalov, A.V. Pipa,
B.I. Rudyak. Interdigital Accelerating H-structure in
the Multiсharged Ion Linac (MILAC) // Review of
Scientific Instruments and Methods. 1998, v. 69,
№ 10, p.3537-3540.
СТЕНДОВАЯ НАЛАДКА НОВОЙ ПРЕДОБДИРОЧНОЙ СЕКЦИИ ЛУМЗИ
В.А. Бомко, А.Ф. Дьяченко, Б.В. Зайцев, А.Ф. Кобец, Е.В. Ивахно, В.И. Мисюра
Приведены результаты настройки на экспериментальном стенде нерегулярной встречно-штыревой уско-
ряющей структуры с фокусировкой высокочастотным полем, внедренной в новой предобдирочной секции
ПОС-4 линейного ускорителя многозарядных ионов (ЛУМЗИ). Разработаны эффективные настроечные уст-
ройства в виде стерженьков, расположенных на боковой поверхности трубок дрейфа противоположно их
подвескам.
СТЕНДОВЕ НАЛАДЖЕННЯ НОВОЇ ПЕРЕДОБДИРКОВОЇ СЕКЦІЇ ЛУМЗІ
В.О. Бомко, О.Ф. Дяченко, Б.В. Зайцев, А.П. Кобець, Є.В. Івахно, В.І. Місюра
Наведено результати настроювання на експериментальному стенді нерегулярної зустрічно-штиревої
прискорюючої структури з фокусуванням високочастотним полем, впровадженої в новій передобдирковій
секції ПОС-4 лінійного прискорювача багатозарядних іонів (ЛУМЗІ). Розроблено ефективні настроювальні
пристрої у вигляді стерженьків, розташованих на боковій поверхні трубок дрейфу протилежно їх підвіскам.
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