Accelerating structure of 10 MEV electron linac
The calculation of the on-axis coupled the biperiodic 10 MeV electron accelerating structure is represented. The one-meter structure includes 19 accelerating cells, two of which are bunching cells. Two versions of RF feeding of accelerating structure 2.5 and 4.5 MW are considered. The peak beam cu...
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| Опубліковано в: : | Вопросы атомной науки и техники |
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| Дата: | 2004 |
| Автори: | , , , , |
| Формат: | Стаття |
| Мова: | Англійська |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2004
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| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Accelerating structure of 10 MEV electron linac / A.A. Zavadtsev, A.A. Krasnov, I.S. Kuzmin, N.P. Sobenin, A.I. Fadin // Вопросы атомной науки и техники. — 2004. — № 2. — С. 47-49. — Бібліогр.: 2 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859943558319964160 |
|---|---|
| author | Zavadtsev, A.A. Krasnov, A.A. Kuzmin, I.S. Sobenin, N.P. Fadin, A.I. |
| author_facet | Zavadtsev, A.A. Krasnov, A.A. Kuzmin, I.S. Sobenin, N.P. Fadin, A.I. |
| citation_txt | Accelerating structure of 10 MEV electron linac / A.A. Zavadtsev, A.A. Krasnov, I.S. Kuzmin, N.P. Sobenin, A.I. Fadin // Вопросы атомной науки и техники. — 2004. — № 2. — С. 47-49. — Бібліогр.: 2 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | The calculation of the on-axis coupled the biperiodic 10 MeV electron accelerating structure is represented. The
one-meter structure includes 19 accelerating cells, two of which are bunching cells. Two versions of RF feeding of
accelerating structure 2.5 and 4.5 MW are considered. The peak beam current is 0.14 and 0.3 A for these versions.
44…49% of the injected current is accelerated. Shunt impedance is 74 MOhm/m with the 8 mm aperture diameter.
Приведено результати розрахунку біперіодичної структури електронного прискорювача на енергію 10 МеВ зі
зв'язком по осі. Метрова структура має 19 прискорюючих осередків, два з яких такі, що групують. Розглянуто два
варіанти ВЧ-живлення структури потужністю 2,5 і 4,5 МВт. Амплітудне значення струму для цих варіантів дорівнюють 0.14 і 0.3 А, що забезпечує захоплення в процес прискорення 44...49% електронів. Структура з апертурою 8 мм має
ефективний шунтовий опір 74 МОм/м.
Приведены результаты расчета бипериодической ускоряющей структуры электронного ускорителя на энергию
10 МэВ со связью по оси. Метровая структура имеет 19 ускоряющих ячеек, две из которых группирующие. Рассмотрены
два варианта ВЧ-питания ускоряющей структуры мощностью 2,5 и 4,5 МВт. Амплитудные значения тока для этих вариантов равны 0.14 и 0.3 А, что обеспечивает захват в процесс ускорения 44…49% электронов. Структура с апертурой
8 мм имеет эффективное шунтовое сопротивление 74 МОм/м.
|
| first_indexed | 2025-12-07T16:11:52Z |
| format | Article |
| fulltext |
ACCELERATING STRUCTURE OF 10 MEV ELECTRON LINAC
A.A.Zavadtsev
IntroScan, P.O.BOX 18, 19 Vereyskaya Str., Moscow, 121357 Russia, introscan@mtu-net.ru
A.A.Krasnov, I.S.Kuzmin, N.P.Sobenin, A.I.Fadin
Moscow Physics Engineering Institute (State University)
31 Kashirskoe Sh., Moscow, 115409 Russia
The calculation of the on-axis coupled the biperiodic 10 MeV electron accelerating structure is represented. The
one-meter structure includes 19 accelerating cells, two of which are bunching cells. Two versions of RF feeding of
accelerating structure 2.5 and 4.5 MW are considered. The peak beam current is 0.14 and 0.3 A for these versions.
44…49% of the injected current is accelerated. Shunt impedance is 74 MOhm/m with the 8 mm aperture diameter.
PACS: 27.17.+w
1. INPUT DATA
High beam power electron linacs with theenergy up
to 10 MeV found more and more various industry appli-
cations. A variant of a pulse mode normal conductivity
electron linac with an on-axis coupled biperiodic accel-
erating structure is considered.
The 2856 MHz klystron is used as a RF- power source
for the accelerating structure. Two versions of RF feeding
of the accelerating structure are considered: peak RF power
is up to 2.5 MW in Version 1 and up to 4.5 MW in Version
2. The maximum RF pulse width of the klystron is 20 µ
sec. But the operating RF pulse width will be chosen in the
range 10...20 µsec (13.5 µsec nominal) to decrease the RF
breakdown possibility. Maximum average RF power is
22.5 kW. Nominal beam power is 4.6 kW.
Two variants of a 40 kV three-electrode electron gun
are considered as an electron source. Variant #1 is an in-
jector with a concave cathode and a focusing electrode.
Applying an additional negative voltage to the focusing
electrode, we can cut off the injected current. Calculated
beam diameter in crossover is di=0.7...1.0 mm. Variant
#2 is an injector with a flat grid controlled cathode and a
focusing electrode at the grid voltage. Changing the grid
voltage, we can control the injected current Ii in the
range from 0 to maximum value and therefore control the
accelerated beam current Ib. The calculated beam diame-
ter in crossover is di=1.0...1.4 mm.
The RF field of the accelerating structure focuses the
electron beam. An external solenoid is not required. The
electric field, accelerating and drift spaces in the bunching
part of the structure were optimized to get a maximum cap-
ture ratio kc=Ib/Ii and requid accelerated beam parameters.
2. CHOICE OF OPTIMUM VARIANT
The electron linac was calculated in four main steps.
Step #1: the accelerating cell form is compromised
using the SUPERFISH computer program to get a maxi-
mum shunt impedance and satisfied maximum surface
electric field.
Step #2: main required parameters of the structure
are calculated using analytic relations [1] and data cal-
culated during Step #1.
Step #3: electric field, accelerating and drift gaps in
the bunching part of the structure are optimized using
the PARMELA program to get a maximum kc and satis-
fied energy spectrum.
Step #4: variational parameters are calculated
(accelerated electron beam parameters depending on RF
power P, injected current Ii, injector voltage Ui).
Accelerating structure includes 2 bunching cells, 17
regular accelerating cells, 18 coupling cells and input
waveguide coupler. Input coupler is connected to the
last (#19) accelerating cell as it is shown in Fig.1. Aper-
ture diameter is 8 mm. Length of drift tube nose is
3 mm for bunching cells and 4 mm for the rest cells. Di-
aphragm thickness is 4 mm. Radius of the cells is cho-
sen to get operating frequency 2856 MHz.
Fig.1. Form of the structure
Calculated values of effective shunt impedance ZT2
and unloaded Q-factor Q0 are represented in Table 1.
Table 1. Accelerating cell parameters
Cell No. Q0 ZT2, MOm/m
1 12045 50.3
2 13269 53.2
3-19 17950 74.1
The bunching part of the structure was optimized to
get a maximum kc, required most probable Em and aver-
age Ea energies and energy spectrum. Following parame-
ters of the bunching part of the structure were changed
during this optimization: cell length, accelerating gap
length, drift gap length and electric field in the cell.
Table 2. Beam dynamic calculation results
Parameter Version 1 Version 2
RF power, MW 2.5 4.5
Field in cell #1, MV/m 5.80
Field in cell #2, MV/m 14.40
Field in cell #3-19, MV/m 15.00
Injection current, A 0.225 0.5
Accelerated current, A 0.108 0.22
Capture ratio, % 48.1 44.4
Average energy, MeV 9.36 10.56
Most probable energy, MeV 10.28 11.82
Beam power, MW 1.01 2.32
RF loss in the structure, MW 1.45 2.02
Lost beam loss power, MW 0.105 0.12
Following model was used during calculation of the
bunching part with PARMELA program: accelerating
cell #1, coupling cell, accelerating cell #2, coupling cell
and accelerating cell #3.
___________________________________________________________
PROBLEMS OF ATOMIC SIENCE AND TECHNOLOGY. 2004. № 2.
Series: Nuclear Physics Investigations (43), p.47-49. 47
Main results of the beam dynamics calculation for two
RF power levels are represented in Table 2 and in Fig.2.
The typical energy spectrum and beam cross-section
are shown in Fig.3.
Fig.2. Accelerating field distribution
Fig.3. Typical energy spectrum (keV) and beam cross-
section (cm)
3. VARIATIONAL PARAMETERS
Dependence of accelerated beam parameters on in-
jection voltage, injected current and klystron RF power
were investigated. The results of calculation are repre-
sented in Table 3, Fig.4 and 5.
Table 3. Injection voltage variation
Ver. Ui, kV kc, % Ib, A Em, MeV Ea, MeV
1
30 45.5 0.11 10.26 9.27
40 48.1 0.11 10.28 9.36
50 49.9 0.11 10.30 9.30
2
30 39.9 0.24 11.68 10.19
40 44.4 0.22 11.82 10.56
50 47.4 0.21 11.88 10.75
The beam current changes in 2% range at RF power
changing in 2.25...2.90 MW range for Version 1 and in
4.5% range at RF power changing in 4.0...4.75 MW
range for Version 2. Analysis of variational parameters
allows us to conclude:
• Injection voltage influences on accelerated
beam parameters very weakly in the range
30...50 kV. Injection voltage can be chosen in
this range taking into account high-voltage pow-
er supply aspects.
• Changing the peak RF power and injected beam
current we can choose the operating mode in
wide range of beam parameters, namely for Ver-
sion 1: P=2.5 MW, Ii=0.25 A, Ui=40 kV,
Em=9 MeV, Ea=8.1 MeV, Ib=0.14 A and for Ver-
sion 2: P=4 MW, Ii=0.68 A, Ui=40 kV,
Em=9.0 MeV, Ea=8.1 MeV, Ib=0.3 A. As an ex-
perience shows there are unaccounted power
losses subsequent upon not ideal tuning of the
units in real accelerator. In this case the klystron
power reserve will be used.
4. CALCULATION OF ACCELERATING
STRUCTURE SIZES
The computer program MICROWAVE STUDIO was
used for these calculations with method, described in [2].
The structure sizes were calculated in three main steps.
8
9
10
11
12
13
0,05 0,1 0,15 0,2 0,25 0,3
Ib, A
Ea
, M
eV
Fig.4. Beam load at injection voltage Ui=40 kV and
RF power 2.5 (♦) and 4.5 (•) MW
8
9
10
11
12
2 2,5 3 3,5 4 4,5 5
P , MW
Ea
, M
eV
Fig.5. Average energy dependence on RF power at
injection voltage Ui=40 kV and injected current Ii
0.225 (♦) and 0.5 (•) A
Step #1: calculation of frequency of accelerating and
coupling cells using model including two accelerating
half cells and coupling cell between them.
Step #2: correction of calculation of Step #1 for first
part of the structure using model, including full acceler-
ating cell #1, accelerating half cell #2 and coupling cell
between them.
Step #3: calculation of accelerating cell #19 and in-
put coupler using model including accelerating half cell
#18, full accelerating cell #19, coupling the cell between
them and the input waveguide coupled with accelerating
cell #19.
The accelerating field in the model of regular part of
accelerating structure is shown in Fig.6.
Designed value of coupling coefficient of the input
coupler is 2.1 for Version 1 and 3.4 for Version 2. The
input waveguide is coupled with the structure through
rectangular coupling window. The calculation model in-
cludes: accelerating half cell #18, full accelerating cell
#19, coupling cell between them and input waveguide
coupled with accelerating cell #19 through rectangular
window. The window width (parallel to structure axis)
is equal to 13.2 mm. The coupling coefficient β1.5 of this
model (1.5 accelerating cells) relates with coupling co-
efficient of the whole structure β19 (19 accelerating
cells) with the same coupling window by following rela-
tion:
5.1
19
195.1 L
Lββ = ,
where L19 and L1.5 are the lengths of the whole structure
and the model.
The coupling coefficient dependence on the cou-
pling window length (perpendicular to the structure
axis) is shown in Fig.7. The accelerating field distribu-
tion in input coupler is shown in Fig.8.
48
Fig.6. The accelerating field in the model of regu-
lar part of accelerating structure
1,0
1,5
2,0
2,5
3,0
3,5
4,0
26,0 26,2 26,4 26,6 26,8 27,0 27,2
Coupling window length, mm
C
ou
pl
in
g
co
ef
fic
ie
nt
Fig.7. Input coupler tuning
Fig.8. Field distribution in the input coupler
5. AVERAGE THERMAL CONDITION
A maximum average RF power is 22.5 kW. The pow-
er dissipated in the structure in this case is equal to
11.3 kW in Version 1 and 7.7 kW in Version 2. The cool-
ing of the structure is realized by the water flow through
16 channels in the cell body as this is shown in Fig.9.
Four channels are connected in parallel so that the
water flows four times through the structure in opposite
directions in turn as this is shown in Fig.10.
The thermal calculation results are: water flow is
38 dm3/min, outlet-inlet temperature difference is 0.20C,
water-copper temperature difference is 6.50C, water
speed is 2 m/sec for maximum power 11 kW dissipated
in the structure.
Fig.9. Detail of accelerating structure
Fig.10. Water channels in the accelerating structure
6. SUMMARY
The calculated parameters of the accelerator operat-
ed in two modes at maximum klystron average power
and in nominal beam power mode, corresponding to
Version 1 and Version 2, are represented in Table 4.
Table 4. Facility parameters
Parameter Version 1 Version 2
Peak RF power, MW 2.5 4.0
Average RF power (max/nom), kW 22.5/15 22.5/9
Most probable energy, MeV 9 9
Average energy, MeV 8.1 8.1
Beam current width, µsec 12 12
Frequency repetition (max/nom),
Hz
600/430 400/160
Average structure loss
(max/nom), kW
11.3/8.3 7.7/3.1
Average beam power (max/nom),
kW
7.8/4.6 11.6/4.6
Taking into account unaccounted power losses, one
may conclude, that the nominal total beam power of the
facility is up to 7.5 kW for Version 1 and up to 10 kW
for Version 2. Nominal beam power is 4.6 kW in both
Versions.
REFERENCES
1. B.V.Zverev, N.P.Sobenin, Electrodynamic Charac-
teristics of Accelerating Cavities, Moscow: Ener-
goatomizdat, 1993.
2. I.S.Kuzmin, N.P.Sobenin, A.A.Sulimov. Calcula-
tion of 3D Model of Biperiodic Accelerating Struc-
ture with Variable Phase Velocity. Proceedings of
MEPhI Science Session. 2003, p.122-124.
УСКОРЯЮЩАЯ СТРУКТУРА ЛИНЕЙНОГО ЭЛЕКТРОННОГО УСКОРИТЕЛЯ НА ЭНЕРГИЮ 10 МэВ
А.А. Завадцев, А.А. Краснов, И.С. Кузьмин, Н.П. Собенин, А.И. Фадин
Приведены результаты расчета бипериодической ускоряющей структуры электронного ускорителя на энергию
10 МэВ со связью по оси. Метровая структура имеет 19 ускоряющих ячеек, две из которых группирующие. Рассмотрены
два варианта ВЧ-питания ускоряющей структуры мощностью 2,5 и 4,5 МВт. Амплитудные значения тока для этих вари-
антов равны 0.14 и 0.3 А, что обеспечивает захват в процесс ускорения 44…49% электронов. Структура с апертурой
8 мм имеет эффективное шунтовое сопротивление 74 МОм/м.
ПРИСКОРЮЮЧА СТРУКТУРА ЛІНІЙНОГО ЕЛЕКТРОННОГО ПРИСКОРЮВАЧА НА ЕНЕРГІЮ 10 МеВ
А.А. Завадцев, А.А. Краснов, И.С. Кузьмін, Н.П. Собенин, А.И. Фадин
Приведено результати розрахунку біперіодичної структури електронного прискорювача на енергію 10 МеВ зі
зв'язком по осі. Метрова структура має 19 прискорюючих осередків, два з яких такі, що групують. Розглянуто два
варіанти ВЧ-живлення структури потужністю 2,5 і 4,5 МВт. Амплітудне значення струму для цих варіантів дорівнюють
___________________________________________________________
PROBLEMS OF ATOMIC SIENCE AND TECHNOLOGY. 2004. № 2.
Series: Nuclear Physics Investigations (43), p.47-49. 49
0.14 і 0.3 А, що забезпечує захоплення в процес прискорення 44...49% електронів. Структура з апертурою 8 мм має
ефективний шунтовий опір 74 МОм/м.
50
Fig.7. Input coupler tuning
Fig.8. Field distribution in the input coupler
REFERENCES
А.А. Завадцев, А.А. Краснов, И.С. Кузьмін, Н.П. Собенин, А.И. Фадин
|
| id | nasplib_isofts_kiev_ua-123456789-79326 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T16:11:52Z |
| publishDate | 2004 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Zavadtsev, A.A. Krasnov, A.A. Kuzmin, I.S. Sobenin, N.P. Fadin, A.I. 2015-03-31T09:07:52Z 2015-03-31T09:07:52Z 2004 Accelerating structure of 10 MEV electron linac / A.A. Zavadtsev, A.A. Krasnov, I.S. Kuzmin, N.P. Sobenin, A.I. Fadin // Вопросы атомной науки и техники. — 2004. — № 2. — С. 47-49. — Бібліогр.: 2 назв. — англ. 1562-6016 PACS: 27.17.+w https://nasplib.isofts.kiev.ua/handle/123456789/79326 The calculation of the on-axis coupled the biperiodic 10 MeV electron accelerating structure is represented. The one-meter structure includes 19 accelerating cells, two of which are bunching cells. Two versions of RF feeding of accelerating structure 2.5 and 4.5 MW are considered. The peak beam current is 0.14 and 0.3 A for these versions. 44…49% of the injected current is accelerated. Shunt impedance is 74 MOhm/m with the 8 mm aperture diameter. Приведено результати розрахунку біперіодичної структури електронного прискорювача на енергію 10 МеВ зі зв'язком по осі. Метрова структура має 19 прискорюючих осередків, два з яких такі, що групують. Розглянуто два варіанти ВЧ-живлення структури потужністю 2,5 і 4,5 МВт. Амплітудне значення струму для цих варіантів дорівнюють 0.14 і 0.3 А, що забезпечує захоплення в процес прискорення 44...49% електронів. Структура з апертурою 8 мм має ефективний шунтовий опір 74 МОм/м. Приведены результаты расчета бипериодической ускоряющей структуры электронного ускорителя на энергию 10 МэВ со связью по оси. Метровая структура имеет 19 ускоряющих ячеек, две из которых группирующие. Рассмотрены два варианта ВЧ-питания ускоряющей структуры мощностью 2,5 и 4,5 МВт. Амплитудные значения тока для этих вариантов равны 0.14 и 0.3 А, что обеспечивает захват в процесс ускорения 44…49% электронов. Структура с апертурой 8 мм имеет эффективное шунтовое сопротивление 74 МОм/м. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Элементы ускорителей Accelerating structure of 10 MEV electron linac Прискорююча структура лінійного електронного прискорювача на енергію 10 МеВ Ускоряющая структура линейного электронного ускорителя на энергию 10 МэВ Article published earlier |
| spellingShingle | Accelerating structure of 10 MEV electron linac Zavadtsev, A.A. Krasnov, A.A. Kuzmin, I.S. Sobenin, N.P. Fadin, A.I. Элементы ускорителей |
| title | Accelerating structure of 10 MEV electron linac |
| title_alt | Прискорююча структура лінійного електронного прискорювача на енергію 10 МеВ Ускоряющая структура линейного электронного ускорителя на энергию 10 МэВ |
| title_full | Accelerating structure of 10 MEV electron linac |
| title_fullStr | Accelerating structure of 10 MEV electron linac |
| title_full_unstemmed | Accelerating structure of 10 MEV electron linac |
| title_short | Accelerating structure of 10 MEV electron linac |
| title_sort | accelerating structure of 10 mev electron linac |
| topic | Элементы ускорителей |
| topic_facet | Элементы ускорителей |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/79326 |
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