Interdigital structures of heavy ions linear accelerators: their tuning, beams focusing and use (review)
The review interdigital H-accelerating structures (IHAS) of the heavy ions linear accelerators developed in NSC KIPT throughout several tens of years is presented. It is shown that in structures with individual stems all kinds of focusings are applicable: quadrupole, grid, alternating-phase (APF, in...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
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Dyachenko, О.F. 2023-12-03T15:48:04Z 2023-12-03T15:48:04Z 2019 Interdigital structures of heavy ions linear accelerators: their tuning, beams focusing and use (review) / О.F. Dyachenko // Problems of atomic science and technology. — 2019. — № 6. — С. 17-22. — Бібліогр.: 23 назв. — англ. 1562-6016 PACS: 29.17.w, 29.27.Bd https://nasplib.isofts.kiev.ua/handle/123456789/195235 The review interdigital H-accelerating structures (IHAS) of the heavy ions linear accelerators developed in NSC KIPT throughout several tens of years is presented. It is shown that in structures with individual stems all kinds of focusings are applicable: quadrupole, grid, alternating-phase (APF, in various variants), high-frequency (in various variants) and their combinations. Corresponding constructive decisions are developed for accelerating structures of different function. Essentially new approaches for their adjustment for the set distribution of an accelerating field and frequency (by countering corner change) and some new regulating elements are offered: the end resonant elements of adjustment (EREA) and inductance-capacitor elements (сontrivances). By results of modelling three real accelerating sections which are created at modernization of the multicharge ions linear accelerator were developed. New variants pre-stripping area of the heavy ions accelerator with the relation of mass number to charge A/q = 20 are offered. Надано огляд зустрічно-штирових прискорювальних структур лінійних прискорювачів важких іонів, що розроблялися в ННЦ ХФТІ протягом декількох десятків років. Показано, що в структурах з індивідуальними штангами застосовні всі види фокусувань: квадрупольна, сіткова, змінно-фазова у різних варіантах, високочастотна у різних варіантах та їх комбінації. Для прискорювальних структур різного призначення розроблено відповідні конструктивні рішення. Запропоновано принципово нові підходи для їх настроювання на заданий розподіл прискорювального поля й частоту (шляхом зміни кута зустрічності) і декілька нових регулювальних елементів: кінцеві резонансні елементи настроювання та індуктивно-ємнісні елементи (контрики). За результатами моделювання розроблено три реальні прискорювальні секції, які створювалися при модернізації лінійного прискорювача багатозарядних іонів. Запропоновано нові варіанти передобдиркової ділянки прискорювача важких іонів із відношенням масового числа до зарядового A/q = 20. Представлен обзор встречно-штыревых ускоряющих структур линейных ускорителей тяжелых ионов, разрабатывавшихся в ННЦ ХФТИ на протяжении нескольких десятков лет. Показано, что в структурах с индивидуальными штангами применимы все виды фокусировок: квадрупольная, сеточная, переменно- фазовая в различных вариантах, высокочастотная в различных вариантах и их комбинации. Для ускоряющих структур различного назначения разработаны соответствующие конструктивные решения. Предложены принципиально новые подходы для их настройки на заданное распределение ускоряющего поля и частоту (путем изменения угла встречности) и несколько новых регулирующих элементов: концевые резонансные элементы настройки и индуктивно-емкостные элементы (контрики). По результатам моделирования разработаны три реальные ускоряющие секции, которые создавались при модернизации линейного ускорителя многозарядных ионов. Предложены новые варианты предобдирочного участка ускорителя тяжелых ионов с отношением массового числа к зарядовому A/q = 20. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Theory and technology of particle acceleration Interdigital structures of heavy ions linear accelerators: their tuning, beams focusing and use (review) Зустрічно-штирові структури лінійних прискорювачів важких іонів: їх настроювання, фокусування пучків та використання (огляд) Встречно-штыревые структуры линейных ускорителей тяжелых ионов: их настройка, фокусировка пучков и использование (обзор) Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
| title |
Interdigital structures of heavy ions linear accelerators: their tuning, beams focusing and use (review) |
| spellingShingle |
Interdigital structures of heavy ions linear accelerators: their tuning, beams focusing and use (review) Dyachenko, О.F. Theory and technology of particle acceleration |
| title_short |
Interdigital structures of heavy ions linear accelerators: their tuning, beams focusing and use (review) |
| title_full |
Interdigital structures of heavy ions linear accelerators: their tuning, beams focusing and use (review) |
| title_fullStr |
Interdigital structures of heavy ions linear accelerators: their tuning, beams focusing and use (review) |
| title_full_unstemmed |
Interdigital structures of heavy ions linear accelerators: their tuning, beams focusing and use (review) |
| title_sort |
interdigital structures of heavy ions linear accelerators: their tuning, beams focusing and use (review) |
| author |
Dyachenko, О.F. |
| author_facet |
Dyachenko, О.F. |
| topic |
Theory and technology of particle acceleration |
| topic_facet |
Theory and technology of particle acceleration |
| publishDate |
2019 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Зустрічно-штирові структури лінійних прискорювачів важких іонів: їх настроювання, фокусування пучків та використання (огляд) Встречно-штыревые структуры линейных ускорителей тяжелых ионов: их настройка, фокусировка пучков и использование (обзор) |
| description |
The review interdigital H-accelerating structures (IHAS) of the heavy ions linear accelerators developed in NSC KIPT throughout several tens of years is presented. It is shown that in structures with individual stems all kinds of focusings are applicable: quadrupole, grid, alternating-phase (APF, in various variants), high-frequency (in various variants) and their combinations. Corresponding constructive decisions are developed for accelerating structures of different function. Essentially new approaches for their adjustment for the set distribution of an accelerating field and frequency (by countering corner change) and some new regulating elements are offered: the end resonant elements of adjustment (EREA) and inductance-capacitor elements (сontrivances). By results of modelling three real accelerating sections which are created at modernization of the multicharge ions linear accelerator were developed. New variants pre-stripping area of the heavy ions accelerator with the relation of mass number to charge A/q = 20 are offered.
Надано огляд зустрічно-штирових прискорювальних структур лінійних прискорювачів важких іонів, що розроблялися в ННЦ ХФТІ протягом декількох десятків років. Показано, що в структурах з індивідуальними штангами застосовні всі види фокусувань: квадрупольна, сіткова, змінно-фазова у різних варіантах, високочастотна у різних варіантах та їх комбінації. Для прискорювальних структур різного призначення розроблено відповідні конструктивні рішення. Запропоновано принципово нові підходи для їх настроювання на заданий розподіл прискорювального поля й частоту (шляхом зміни кута зустрічності) і декілька нових регулювальних елементів: кінцеві резонансні елементи настроювання та індуктивно-ємнісні елементи (контрики). За результатами моделювання розроблено три реальні прискорювальні секції, які створювалися при модернізації лінійного прискорювача багатозарядних іонів. Запропоновано нові варіанти передобдиркової ділянки прискорювача важких іонів із відношенням масового числа до зарядового A/q = 20.
Представлен обзор встречно-штыревых ускоряющих структур линейных ускорителей тяжелых ионов, разрабатывавшихся в ННЦ ХФТИ на протяжении нескольких десятков лет. Показано, что в структурах с индивидуальными штангами применимы все виды фокусировок: квадрупольная, сеточная, переменно- фазовая в различных вариантах, высокочастотная в различных вариантах и их комбинации. Для ускоряющих структур различного назначения разработаны соответствующие конструктивные решения. Предложены принципиально новые подходы для их настройки на заданное распределение ускоряющего поля и частоту (путем изменения угла встречности) и несколько новых регулирующих элементов: концевые резонансные элементы настройки и индуктивно-емкостные элементы (контрики). По результатам моделирования разработаны три реальные ускоряющие секции, которые создавались при модернизации линейного ускорителя многозарядных ионов. Предложены новые варианты предобдирочного участка ускорителя тяжелых ионов с отношением массового числа к зарядовому A/q = 20.
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1562-6016 |
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https://nasplib.isofts.kiev.ua/handle/123456789/195235 |
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Interdigital structures of heavy ions linear accelerators: their tuning, beams focusing and use (review) / О.F. Dyachenko // Problems of atomic science and technology. — 2019. — № 6. — С. 17-22. — Бібліогр.: 23 назв. — англ. |
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ISSN 1562-6016. ВАНТ. 2019. №6(124) 17
INTERDIGITAL STRUCTURES OF HEAVY IONS LINEAR
ACCELERATORS: THEIR TUNING, BEAMS FOCUSING AND USE
(REVIEW)
О.F. Dyachenko
National Science Center “Kharkov Institute of Physics and Technology”, Kharkiv, Ukraine
E-mail: dyachenkoa@kipt.kharkov.ua
The review interdigital H-accelerating structures (IHAS) of the heavy ions linear accelerators developed in NSC
KIPT throughout several tens of years is presented. It is shown that in structures with individual stems all kinds of
focusings are applicable: quadrupole, grid, alternating-phase (APF, in various variants), high-frequency (in various
variants) and their combinations. Corresponding constructive decisions are developed for accelerating structures of
different function. Essentially new approaches for their adjustment for the set distribution of an accelerating field
and frequency (by countering corner change) and some new regulating elements are offered: the end resonant ele-
ments of adjustment (EREA) and inductance-capacitor elements (сontrivances). By results of modelling three real
accelerating sections which are created at modernization of the multicharge ions linear accelerator were developed.
New variants pre-stripping area of the heavy ions accelerator with the relation of mass number to charge A/q = 20
are offered.
PACS: 29.17.w, 29.27.Bd
INTRODUCTION
Studying interdigital H-accelerating structures
(IHAS) in NSC KIPT has begun V.А. Bomko almost at
once after publications J.P. Blewett [1] and J. Pottier [2]
and also proceeded the next years under its direct man-
agement [3].
At excitation in the empty cylindrical resonator of
type Н waves field distribution in which there is no axi-
al component of electric field is established. However
there is a possibility to pick up an arrangement of accel-
erating system elements in the resonator in such a man-
ner that between them the longitudinal component of
electric field is formed. For example, if drift tubes to
connect serially to the opposite sides of the resonator
lateral surface there will be a radical redistribution of
fields: electric field will be concentrated in gaps be-
tween drift tubes, and magnetic around current ele-
ments. Such design using a wave of type Н, and has
been offered for the first time J.P. Blewett in 1956 (in-
terdigital H structure with drift tubes on individual sus-
pension brackets, Fig. 1). One year later J. Pottier has
suggested to use for fastening of drift tubes two plate-
combs which are located counter on a lateral surface of
the resonator and not reaching its edges (Comb struc-
ture, Fig. 2).
Fig. 1. Accelerating structure, proposed by J.P. Blewett
The work purpose is the review interdigital H-
accelerating structures of the heavy ions linear accelera-
tors developed in NSC KIPT. At that possibilities of
their adjustment and use in them of all existing kinds of
bunches focusing are shown.
Fig. 2. Comb structure J. Pottier
1. RESEARCH PROBLEM
OF THE INTERDIGITAL
H-ACCELERATING STRUCTURES
The wave with a longitudinal magnetic field (type
Н111) form distribution of transversal electric field into
rezonator of sinusoidal character. Entering into resona-
tor of counter probes with tubes of drift of one diameter
with identical periodicity this dependence do not break.
However in the non-uniform structure calculated on
acceleration of charged particles, considerable defor-
mation of an accelerating field distribution along struc-
ture and frequency change of a wave working length
takes place. New methods of adjustment and the effec-
tive tuning elements which are not leading to essential
deterioration of structure electrodynamic characteristics
were necessary for compensation of these changes.
The conducted researches IHAS have been devoted
it. Corresponding constructive decisions were developed
for heavy ions linear accelerators of different function.
At that the basic attention was given to creation of the
new sections of the multicharge ions linear accelerator
(MILAC).
2. NEW METHODS OF ADJUSTMENT
Great volume of the spent researches on models
IHAS has allowed to create the first prototype of this
type structure, intended for acceleration of ions with
A/q = 7 to energy 1 MeV/u on length of a wave of
6.3 m. This structure has been calculated on sinusoidal
ISSN 1562-6016. ВАНТ. 2019. №6(124) 18
distribution of an accelerating field along the resonator.
Such distribution was reached by increase of the resona-
tor diameter from 73 cm on the input end to 125 cm on
the output end (Fig. 3). The resonator length has made
3.6 m, quantity of drift tubes (identical diameter) 43,
grid focusing [4].
Fig. 3. Conical resonator
Theoretically this method of adjustment has the ideal
decision. However the difficult law of diameter change
complicates resonator manufacturing techniques. Thus
there is no possibility of thin adjustment of cells. The
decision of this problem for IHAS with drift tubes on
individual stems is found on a way of the refusal of tra-
ditional representation about such structure according to
which a counter corner, i. e. the corner between two
next counter probes, should make 180°. As means of
adjustment of non-uniform structure cells possibility of
change of this corner from 180° on last, longest cells to
sizes of corners on the others which provide the de-
manded law of a field distribution along structure was
used (Fig. 4). It was essentially new approach to ad-
justment such interdigital H structures [5].
Fig. 4. Accelerating structure with countering corner
change φ
The conducted researches have shown that the most
effective is the structure with the additional (adjusting,
current-carrying) stems symmetrically located concern-
ing positioning stems. The separation of the holders
function providing an adjustment of drift tubes and cur-
rent conductivity, has allowed to reconstruct electric
field distributions in more wide range.
The further development of IHAS design for the
purpose of MILAC new basic section making was the
decision to establish a drift tube of one parity on the
general plate bracket (comb) by means of short stems
while drift tubes of other parity are fixed on adjusting
stems with two additional stems (Fig. 5) [6]. For in-
crease of IHAS efficiency it is necessary to reduce ca-
pacitor loading of the structure. Application quadrupole
focusing imposes certain restrictions on length and di-
ameter of drift tubes. Being guided by positive experi-
ence of use biperiodic character of drift tubes diameters
change on accelerator UNILAC [7], the similar con-
structive decision has been applied. The drift tubes lo-
cated on a plate bracket, did not contain quadrupole
lenses and their diameter increased from the input end
of structure to the output end.
Fig. 5. Accelerating structure with countering corner
change and plate bracket
Action of adjusting stems was supplemented with
other tuning elements (resonant type) which have been
developed for the first time and named by end resonant
elements of adjustment (EREA). Constructively they
represent the quarter wave resonant vibrators formed on
the ends of the plate bracket with the help undercuts it
from the side of a resonator wall and shorten at the ex-
pense of capacity of drift tubes placed on them (Fig. 6)
[8, 9]. If adjustment current-carrying stems was local on
each cell separately, but EREA tuning had global char-
acter. With their help it was possible to reconstruct (in-
cline) to all distribution of an accelerating field.
Fig. 6. Accelerating structure with end resonant
elements of adjustment
As a result of the spent researches of IHAS tuning
on the set (uniform) distribution of electric field and
demanded frequency the possibility of these require-
ments performance by means of the develop adjustment
elements is shown: the additional adjusting stems placed
on drift tubes of the one row; EREA, and also a choice
of the form of a plate bracket and reduction of drift
tubes diameters of other row at quadrupole focusing.
The data obtained in the process of experimental re-
searches is taken as a principle modernisations MILAC.
3. THE BASIC AND PRESTRIPPER
SECTIONS MILAC
The reached successes on development of the IHAS
allowed to create, as a matter of fact, the new accelera-
tor. By means of the specified methods combination of
ISSN 1562-6016. ВАНТ. 2019. №6(124) 19
adjustment for the first time it was success to generate
uniform distribution of an accelerating field in the reso-
nator of the big length for the basic section (BS)
MILAC. It provided the highest rate of acceleration:
almost twice above, than in former section on structure
Alvaretsa. The length of the resonator from 16.2 to
11.2 m was thus reduced (at the same diameter 1.5 m),
raised A/q from 3.5 to 5 and working length of a wave
in 3 times (6.3 m). The last has allowed to increase the
longitudinal sizes of the drift tubes, having reduced their
quantity in 2.2 times (from 88 to 40, of them only 20
with quadrupole lenses). Interior of the BS MILAC is
presented on Fig. 7 [10]. On BS model possibility of
smooth regulation of ions energy at the expense of a
field areas of various extent creation [11] for the first
time is shown.
Fig. 7. Interior of the basic section MILAC
At the same time with creation of the BS researches
on models prestripper sections (PSS) were conducted.
Various variants of focusing were considered: quadru-
pole and two grid (on different lengths of waves: 12.6
and 6.3 m).
The calculation strong-focusing variant PSS and
modelling have shown that at a wave length of 12.6 m
the quantity of drift tubes must be 37 (of them 18 with
quadrupole lenses) in the resonator length 8,66 m and
diameter 1.3 m. Thus in an initial part are used cells
with alternating multiplicity of drift. The section is cal-
culated on acceleration of ions with A/q = 22 and is
structurally similar BS [12].
The variant with grid focusing reduces the general
intensity of an accelerated ions bunch. However high
acceleration rate allows to accelerate ions with lower
charging (A/q = 30) which intensity above that compen-
sates to some degree losses on grids. Reduction of all
drift tubes diameters (unlike quadrupole focusings)
which there should be 51 pieces in the resonator length
8.2 m and diameter 1.4 m, raises shunt resistance. New
variant of the IHAS [13] in which odd drift tubes are
located on longitudinal bearing electrodes, and the ad-
justing stems established symmetrically and uniformly
on length, connect them with a lateral surface of the
resonator is developed for this section. For increase in a
range of adjustment and from constructive reasons it is
offered to shift an axis of structure concerning a resona-
tor axis. The new variant of execution of the EREA in
such structure is developed (Fig. 8,а,b) [14]. Use of the
described elements of adjustment in variant PSS-30 as
have shown researches on model, allow to receive uni-
form distribution of electric field along structure at
wave length 12.6 m.
а b
Fig. 8. Models of the quadrupole (a) and grid (b, with
the shifted axis of structure) variants of the PSS MILAC
Unfortunately, any of these variants has not been
carried out for the various reasons. The prestripper sec-
tion has been developed on a wave length 6.3 m with
grid focusing, with structure in the rectangular resonator
(0.90 × 1.16 m) and without shift from its axis. The sec-
tion in length of 4 m, contains 46 tubes of drift and in it
ions with A/q ≤15 are accelerated. Adjustment of sec-
tion for the set parametres was spent only by change of
the drift tubes diameters and three EREA. The mobile
lateral wall could be used for frequency change. Accel-
erating structure of the PSS-15 is shown on Fig. 9 [15].
Fig. 9. Accelerating structure of the PSS-15 MILAC
4. DEVELOPMENT OF VARIOUS
PROJECTS OF HEAVY IONS LINEAR
ACCELERATORS
For reconstruction of the protons linear accelerator
of PLAC-9 for the purpose of its transformation into the
heavy ions accelerator (A/q = 20) by output energy
1 MeV/u variant of the IHAS with the grid focusing of a
bunch calculated on essential increase of a wave length
(from 2.1 to 12.6 m) is created. The design of accelerat-
ing structure is similar to grid variant of the PSS
MILAC, the same resonator length 6 m and diameter
1.5 m (quantity of drift tubes 36) was thus used. As the
sizes of the resonator are already set, adjustment for the
set frequency was spent, mainly, by means of additional
stems [14].
For the first time IHAS with individual stems has
been applied with modified alternating-phase focusing
(MAFF) a bunch in the basic section intended for accel-
eration of ions +14
184W from energy 419 keV/u to
1.7 MeV/u (the project of an accelerating complex to
mass production of track membranes at factory
"Теnzоr" Dubna, Russia, 1991). The carried out calcula-
tion and modelling have shown that at frequency of RF-
oscillation 81.4 MHz the quantity of drift tubes should
be 58 (length from 1.53 to 19.06 cm) in the length reso-
nator 5.69 m and diameter 0.74 m. Constructively ac-
ISSN 1562-6016. ВАНТ. 2019. №6(124) 20
celerating structure is executed in the form of the IHAS
with shifted an axis of a bunch concerning an axis of the
resonator and an arrangement of odd drift tubes on lon-
gitudinal bearing elements with uniform distribution to
them current-carrying adjusting stems. On the input and
output ends of accelerating structure are EREA
(Fig. 10). For frequency adjustment in small limits in
the process of accelerator work, without given distribu-
tion of the set accelerating field, it is established on two
probes in diameter 2.4 сm (for full-scale structure) on an
input and output of resonator symmetrically at an angle
45° to a plane of accelerating structure symmetry. At
immersing of all probes on 15.0 сm frequency goes
down on 150 kHz.
Fig. 10. Model of the basic section with MAFF
and lateral probes for frequency adjustment
For Moscow Meson Factory five sections with the
IHAS from six under the project of the linear accelera-
tor radioactive nuclides (LARАN), operating in a con-
tinuous mode in an energy range from 1 keV/u to
6.5 MeV/u with various types of bunches focusing [16]
are investigated. In the first section which accelerates
ions from energy 1 to 60 keV/u with A/q = 60 at work-
ing frequency 27.12 MHz (develops ITEP) is used RFQ
focusing. After acceleration in two sections with mag-
netic periodic focusing to energy 350 keV/u (at the
same frequency and A/q) the bunch of ions is stripped
on a firm carbon target. The fourth section is calculated
on acceleration with A/q = 7 (as well as the others) to
energy 2.786 MeV/u with working frequency
54.24 MHz. Singularity of this and two subsequent sec-
tions is realisation of ions acceleration on AFF with a
zero synchronous phase [17]. Design feature of 4th and
5th sections is presence in resonators as focusing ele-
ments quadrupole triplets between areas of regular ac-
celerating structure (in 4th section – two and 5th – one
triplet). Last two sections are excited on frequency of
108.48 MHz. Models of five sections with IHAS
(Fig. 11,а,b) which are adjusted on the given field dis-
tribution and frequency are created, the transversal ge-
ometrical sizes of resonators and all elements are de-
fined, electrodynamic characteristics are measured [18].
Distinctive feature of sections with quadrupole focusing
from OS MILAC is that all elements of adjustment both
resonant, and not resonant, are located in row of drift
tubes without quadrupoles. For the first time in IHAS
with individual stems uniform distribution of a field to
the areas of structure divided by triplets is received.
Unfortunately, any of these projects has not been re-
alized for the various reasons though workings out are
finished to a stage of working drawings.
а b
Fig. 11. Models of the second (а)
and the fourth (b) sections LARАN
5. THE HELIUM IONS ACCELERATOR
Development and creation of one more prestripper
section PSS-4 calculated on acceleration of intensive
bunches of easy ions (A/q = 4, the Не+ ions accelerator)
from energy 30 keV/u to 1 MeV/u, passed in frame-
works of the project of a complex on manufacture radi-
onuclides. In this IHAS for bunch focusing method AFF
with step-by-step change of a synchronous phase along
the focusing periods is used. For strengthening of effi-
ciency of bunches formation the accelerating field in an
initial part of structure increases from a gap to a gap.
The octahedral resonator with diameter of the entered
circle 1.075 m and length 2.395 m contains 32 drift
tubes and is excited on frequency of 47.2 MHz. As a
result of the carry out adjusting operations electric field
distribution in gaps of accelerating structure close to
given is received, but at higher value of resonant fre-
quency (almost on 1 MHz). The problem of resonant
frequency change at preservation of demanded distribu-
tion of electric field in H-structures always stood sharp-
ly enough because coherence of adjustment processes.
In this connection new effective inductance-capacitor
adjusting devices (сontrivances) in the form of the rods
located on the side of drift tubes, opposite to their sus-
pension brackets are developed. At a certain design ver-
sion local fine tuning of cells probably to carry out not
only selection of diameter and length сontrivances, but
also change of a corner of their arrangement concerning
an axis of suspension brackets of drift tubes. On Fig. 12
the interior of the PSS-4 (the helium ions accelerator)
resonator is presented.
Fig. 12. Accelerating structure of the PSS-4
High efficiency of such inductance-capacitor adjust-
ing system allows to receive demanded electrodynamic
characteristics of accelerating structure at identical
small diameter of drift tubes that considerably simplifies
their design, reduces a radiating background round the
ISSN 1562-6016. ВАНТ. 2019. №6(124) 21
accelerator and prevents initiation of the multipacting
high-frequency discharge [19, 20].
6. NEW VARIANTS PRESTRIPPER AREA
OF THE MILAC
The accelerate and focusing channel high-current of
the heavy ions linear accelerator with A/q ≤ 20 on the
basis of the IHAS is offered. The channel is calculated
on formation and acceleration of a bunch from energy
6 keV/u to 1 MeV/u. Functionally the channel structure
includes an area with RFQ focusing (energy from 6 to
100 keV/u) and prestripper section (energy to 1 MeV/u)
with combined radio-frequency focusing (CHFF = AFF
+ RF-quadrupole) [21, 22]. On model possibility of ad-
justment of structure CHFF on the given distribution of
an accelerating field by means of additional stems and
EREA (Fig. 13).
Fig. 13. Model of an accelerating structure with CHFF
The variant of hybrid accelerating structure, in the
form of combination of structures with RFQ and grid
focusing in one resonator was considered also. For re-
finement of mathematical modelling results and carry-
ing out of various researches of electrodynamic charac-
teristics of extended hybrid structure scale model is de-
signed [23]. On Fig. 14 the accelerating structure with
RFQ is presented.
Fig. 14. Model of the RFQ accelerating structure
CONCLUSIONS
The interdigital H accelerating structures of heavy
ions linear accelerators were developed in NSC KIPT
throughout several tens years. Take into account diffi-
cult character of distribution electric and magnetic fields
in IHAS, raised on a longitudinal magnetic wave of type
Н111, new methods of adjustment and formation of uni-
form distribution of an accelerating field in structure
gaps which are based on use of the various inductive,
capacitor, resonant adjusting systems are developed and
consider in each separate case of feature and appoint-
ment of the IHAS. It is shown that in such structures
with individual stems all kinds of beams focusings are
applicable: quadrupole, net, alternating-phase (AFF, in
various variants), high-frequency (in various variants)
and their combinations. Three accelerating sections
which were created at modernisation MILAC are devel-
oped. New variants prestripping area with A/q = 20 are
offered.
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Article received 25.09.2019
ВСТРЕЧНО-ШТЫРЕВЫЕ СТРУКТУРЫ ЛИНЕЙНЫХ УСКОРИТЕЛЕЙ ТЯЖЕЛЫХ ИОНОВ:
ИХ НАСТРОЙКА, ФОКУСИРОВКА ПУЧКОВ И ИСПОЛЬЗОВАНИЕ (ОБЗОР)
A.Ф. Дьяченко
Представлен обзор встречно-штыревых ускоряющих структур линейных ускорителей тяжелых ионов,
разрабатывавшихся в ННЦ ХФТИ на протяжении нескольких десятков лет. Показано, что в структурах с
индивидуальными штангами применимы все виды фокусировок: квадрупольная, сеточная, переменно-
фазовая в различных вариантах, высокочастотная в различных вариантах и их комбинации. Для ускоряю-
щих структур различного назначения разработаны соответствующие конструктивные решения. Предложены
принципиально новые подходы для их настройки на заданное распределение ускоряющего поля и частоту
(путем изменения угла встречности) и несколько новых регулирующих элементов: концевые резонансные
элементы настройки и индуктивно-емкостные элементы (контрики). По результатам моделирования разра-
ботаны три реальные ускоряющие секции, которые создавались при модернизации линейного ускорителя
многозарядных ионов. Предложены новые варианты предобдирочного участка ускорителя тяжелых ионов с
отношением массового числа к зарядовому A/q = 20.
ЗУСТРІЧНО-ШТИРОВІ СТРУКТУРИ ЛІНІЙНИХ ПРИСКОРЮВАЧІВ ВАЖКИХ ІОНІВ:
ЇХ НАСТРОЮВАННЯ, ФОКУСУВАННЯ ПУЧКІВ ТА ВИКОРИСТАННЯ (ОГЛЯД)
О.Ф. Дьяченко
Надано огляд зустрічно-штирових прискорювальних структур лінійних прискорювачів важких іонів, що
розроблялися в ННЦ ХФТІ протягом декількох десятків років. Показано, що в структурах з індивідуальними
штангами застосовні всі види фокусувань: квадрупольна, сіткова, змінно-фазова у різних варіантах, високо-
частотна у різних варіантах та їх комбінації. Для прискорювальних структур різного призначення розробле-
но відповідні конструктивні рішення. Запропоновано принципово нові підходи для їх настроювання на зада-
ний розподіл прискорювального поля й частоту (шляхом зміни кута зустрічності) і декілька нових регулю-
вальних елементів: кінцеві резонансні елементи настроювання та індуктивно-ємнісні елементи (контрики).
За результатами моделювання розроблено три реальні прискорювальні секції, які створювалися при модер-
нізації лінійного прискорювача багатозарядних іонів. Запропоновано нові варіанти передобдиркової ділянки
прискорювача важких іонів із відношенням масового числа до зарядового A/q = 20.
INTRODUCTION
6. NEW variants PRESTRIPPER AREA OF THE MILAC
conclusions
|