Operation of the Moskow Meson Factory linac proton injector with the pulse duration of the beam current up to 150 μs
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| Дата: | 1999 |
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| Формат: | Стаття |
| Мова: | English |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
1999
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| Назва видання: | Вопросы атомной науки и техники |
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| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Operation of the Moskow Meson Factory linac proton injector with the pulse duration of the beam current up to 150 μs / A.S. Belov, V.N. Zubets, V.I. Derbilov, S.K. Esin, E.S. Nikulin, P.N. Ostroumov, O.T. Frolov, V.P. Yakushev // Вопросы атомной науки и техники. — 1999. — № 3. — С. 28-30. — Бібліогр.: 7 назв. — англ. |
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nasplib_isofts_kiev_ua-123456789-811472025-02-10T01:23:34Z Operation of the Moskow Meson Factory linac proton injector with the pulse duration of the beam current up to 150 μs Работа протонного инжектора линейного ускорителя московской мезонной фабрики с длительностью до 150 мкс Belov, A.S. Zubets, V.N. Derbilov, V.I. Esin, S.K. Nikulin, E.S. Ostroumov, P.N. Frolov, O.T. Yakushev, V.P. 1999 Article Operation of the Moskow Meson Factory linac proton injector with the pulse duration of the beam current up to 150 μs / A.S. Belov, V.N. Zubets, V.I. Derbilov, S.K. Esin, E.S. Nikulin, P.N. Ostroumov, O.T. Frolov, V.P. Yakushev // Вопросы атомной науки и техники. — 1999. — № 3. — С. 28-30. — Бібліогр.: 7 назв. — англ. 1562-6016 https://nasplib.isofts.kiev.ua/handle/123456789/81147 en Вопросы атомной науки и техники application/pdf Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| format |
Article |
| author |
Belov, A.S. Zubets, V.N. Derbilov, V.I. Esin, S.K. Nikulin, E.S. Ostroumov, P.N. Frolov, O.T. Yakushev, V.P. |
| spellingShingle |
Belov, A.S. Zubets, V.N. Derbilov, V.I. Esin, S.K. Nikulin, E.S. Ostroumov, P.N. Frolov, O.T. Yakushev, V.P. Operation of the Moskow Meson Factory linac proton injector with the pulse duration of the beam current up to 150 μs Вопросы атомной науки и техники |
| author_facet |
Belov, A.S. Zubets, V.N. Derbilov, V.I. Esin, S.K. Nikulin, E.S. Ostroumov, P.N. Frolov, O.T. Yakushev, V.P. |
| author_sort |
Belov, A.S. |
| title |
Operation of the Moskow Meson Factory linac proton injector with the pulse duration of the beam current up to 150 μs |
| title_short |
Operation of the Moskow Meson Factory linac proton injector with the pulse duration of the beam current up to 150 μs |
| title_full |
Operation of the Moskow Meson Factory linac proton injector with the pulse duration of the beam current up to 150 μs |
| title_fullStr |
Operation of the Moskow Meson Factory linac proton injector with the pulse duration of the beam current up to 150 μs |
| title_full_unstemmed |
Operation of the Moskow Meson Factory linac proton injector with the pulse duration of the beam current up to 150 μs |
| title_sort |
operation of the moskow meson factory linac proton injector with the pulse duration of the beam current up to 150 μs |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
1999 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/81147 |
| citation_txt |
Operation of the Moskow Meson Factory linac proton injector with the pulse duration of the beam current up to 150 μs / A.S. Belov, V.N. Zubets, V.I. Derbilov, S.K. Esin, E.S. Nikulin, P.N. Ostroumov, O.T. Frolov, V.P. Yakushev // Вопросы атомной науки и техники. — 1999. — № 3. — С. 28-30. — Бібліогр.: 7 назв. — англ. |
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Вопросы атомной науки и техники |
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| fulltext |
OPERATION OF THE MOSCOW MESON FACTORY LINAC PROTON
INJECTOR WITH THE PULSE DURATION OF THE BEAM CURRENT
UP TO 150 µS
A.S.Belov, V.N.Zubetz, V.I.Derbilov, S.K.Esin, E.S.Nikulin, P.N.Ostroumov, O.T.Frolov,
V.P.Yakushev
Institute for Nuclear Research, RAS, Moscow
In the autumn of 1998 the RFQ - resonator was
installed [1] at the MMF Linac input. This installation
allowed to reduce the energy of the high-voltage
injector protons from 750 down to 400keV and to
increase the pulse duration of the beam current from 85
up to 150µs without saturation of the core of high-
voltage pulse transformer [2]. A new 50kV artificial line
(AL) was built in the pulse high-voltage generator
(PHVG). It consists of 9 coils with inductance of
1х264mH + 8х132mH and 9 cells of 0.05µF
capacitance each. Actuation of a part of the line
(1х264mH + 5х132mH and 6 cells of capacities)
provides the operational mode at U=750kV and τimp=85
µs, and actuation of the whole line provides the mode of
400kV and 150µs. The parameters of the proton injector
at 50Hz repetition rate are given in Table 1.
To increase the duration of sawtooth voltage
which compensates the sloping rise of accelerating
pulse [3], the 300Ohm resistor that was used to connect
the high-voltage capacity-diode stabilizer with "ground"
was changed for the 600Ohm resistor.
Table 1
Parameter Unit Acceleration
Voltage (kV)
750 400
PHVG
The AL rectifier voltage kV 22 12
1-st modulator rectifier voltage kV 12 6.5
Average current of rectifiers A 0.75 0.95
Delay time of the AL thyratron
(2-nd modulator)
µs 55 55
Delay time of the short-circuit
thyratron (3-rd modulator)
µs 140 215
Ion source (IS)
Arc-drop voltage V 120 125
Discharge current A 24 36
Current in the magnet A 0.40 0.62
Extraction voltage kV 14.5 9
Focusing voltage kV 32 26
Injector output beam current mA 135 120
In the IS discharge modulator the AL was
modified to increase the pulse duration of the injector
beam current up to 150µs.
At 400kV voltage the beam from the accelerating
tube (AT) with the electrode geometry for 750 keV
proton energy has a greater size, thus, current
transmission is worse. For this reason it is necessary to
use a more intensive IS operation mode with values of
the magnet current and discharge current increased by
30%.
The particles from a beam halo with oversize,
falling upon the walls of the AT, disturb more strongly
the distribution of accelerating voltage along the AT,
which is made with the help of the water divider. In the
long beam session at 400kV with the large resistance
AT divider the poor stability of the beam forming
caused by above-stated circumstance was marked [4].
Thus the resistance of the water divider at one "flat
electrode – isolator - flat electrode " gap was 200kOhm,
and at the last 18 gaps, which control voltage on the
second accelerating interval of the AT, it was
3600kOhm. The instability means that "the negative
resistance of the beam" become comparable with this
value. For example, 10-kV reduction of voltage at the
second interval invokes the increase of the current on
the electrode by 104V /3,6x106Ohm = 3мА (because of
the hit of particles from the beam halo on the electrode
and much greater current, caused by secondary
electrons). The 2.5 times reduction of the water divider
resistance made the beam forming more stable when
regulating IS extraction and focusing voltages. But for
this purpose it was necessary to make the off-line
system of water supply for the AT divider.
Besides, 8 of 30 "flat electrode - isolator - flat
electrode " gaps were shorted at the grounded end of the
AT in order to have a greater size of the beam crossover
before the low energy beam transport (LEBT) channel
input and, accordingly, the smaller divergence.
In Fig. 1 the beam envelopes in the AT and in the
drift space up to the first solenoid of the LEBT channel
are compared for acceleration modes with energies of
protons 750 and 400keV and initial value of a slope
angle of an envelope r0’=0.2rad. The calculations are
based on the Kapchinskij-Vladimirskij
"microcanonical" beam model [5,7]. It is obvious that
the particles from the beam halo with the energy of
400keV fall more often on the AT electrodes.
750kV=300kV+450kV
35
25
5
15
25
35
0 500 1000 1500 2000 2500 3000
Z
r
28
400kV=220kV+180kV
25
35
15
25
35
45
55
0 500 1000 1500 2000 2500 3000
Z
r
400kV=160kV+240kV
25
35
10
20
30
40
50
60
0 500 1000 1500 2000 2500 3000
Z
r
Fig.1
- the main body of the beam, Ib=120mA,
En=0.25π⋅cm⋅mrad;
- the beam with a halo, Ib=150mA, En=0.5π⋅
cm⋅mrad
The oscillograms of the beam current,
accelerating voltage and its upper part are shown in
Fig. 2. The stability of accelerating voltage from pulse
to pulse in 400kV mode is better than in 750kV mode
because of the greater stability towards high-voltage
sparks and breakdowns in the AT and other high-
voltage equipment [3]. The value of voltage instability
from pulse to pulse is less than ±0.018%, instability of
voltage during the pulse is up to ±0.31%.
The pulse beam current at the injector output is
120-125мА, normalized emittance measured at the end
of the second (out of the three) segment of the LEBT
channel [6] has the value of 0,35π⋅cm⋅mrad for 90% of
65-70mA beam current with 85µs duration.
Beam current pulse
0
20
40
60
80
100
120
140
0 50 100 150 200
t, mcsec
I (mA)
Accelerating voltage pulse
0
50
100
150
200
250
300
350
400
450
0 50 100 150 200 250 300 350 400 450
t (mcsec)
U (kV)
Аccelerating voltage
pulse top
0
5
10
15
20
0 50 100 150 200 250
t (mсsec)
U (kV)
Fig. 2
In 1999 the injector in two long beam sessions
operated for approximately 1100 hours. The
breakdowns connected with high voltage problems were
not observed.
REFERENCES
1. V.A.Andreev et al. Development of RFQ
Accelerator for the MMF Linac. Proceedings of
The 1991 PAC, San-Francisco, 1991.
2. A.S.Belov et al. Proceedings of The ХII
International Conference on Electrostatic
Accelerators (Obninsk, November 25 - 28,
1997), Obninsk, 1999, page 199-206.
29
3. V.N.Zubetz et al. The Stabilization System of 400-
750kV Pulsed Accelerating Voltage. // Problems
of Atomic Science and Techn. 1999. v. 3. Issue:
Nuclear Physics Researches. (34), p. .
4. V.P.Yakushev, A.N.Serbinov, PTE, N1, 1970,
page 241.
5. I.M.Kapchinskij. Dinamika chastic v linejnih
resonansnih uskoritelyah, Moskva, Atomizdat,
1966 (in Russian).
6. V.I.Derbilov et al. Proceedings of the ХV
Conference on Particle Accelerators (Protvino,
1996), volume 2, page 66-69.
7. V.N.Zubetz et al. Analysis and Synthesis of
Electrostatic Focusing and Accelerating Devices
with the Help of Kapchinskij-Vladimirskij
"Microcanonical" Beam Model. // Problems of
Atomic Science and Techn. 1999. v. 3. Issue:
Nuclear Physics Researches. (34), p. .
30
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