Status of 174 Mhz RF system for BEP
The new RF system for the BEP storage ring (which is an injector of VEPP-2000 accelerating complex) will increase the particles energy in the BEP from 0.9 to 1 GeV. RF system operates at a frequency of 174 MHz and consists of an accelerating cavity, RF power generator and control system. Новая ВЧ-си...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
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| Цитувати: | Status of 174 Mhz RF system for BEP / Yu.A. Biryuchevsky, E.I. Gorniker, E.K. Kendjebulatov, S.A. Krutikhin, G.Ya. Kurkin, V.M. Petrov, A.M. Pilan // Вопросы атомной науки и техники. — 2012. — № 3. — С. 49-52. — Бібліогр.: 4 назв. — англ. |
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Biryuchevsky, Yu.A. Gorniker, E.I. Kendjebulatov, E.K. Krutikhin, S.A. Kurkin, G.Ya. Petrov, V.M. Pilan, A.M. 2016-11-13T15:32:01Z 2016-11-13T15:32:01Z 2012 Status of 174 Mhz RF system for BEP / Yu.A. Biryuchevsky, E.I. Gorniker, E.K. Kendjebulatov, S.A. Krutikhin, G.Ya. Kurkin, V.M. Petrov, A.M. Pilan // Вопросы атомной науки и техники. — 2012. — № 3. — С. 49-52. — Бібліогр.: 4 назв. — англ. 1562-6016 PACS: 29.20.db https://nasplib.isofts.kiev.ua/handle/123456789/108664 The new RF system for the BEP storage ring (which is an injector of VEPP-2000 accelerating complex) will increase the particles energy in the BEP from 0.9 to 1 GeV. RF system operates at a frequency of 174 MHz and consists of an accelerating cavity, RF power generator and control system. Новая ВЧ-система накопителя БЭП (являющегося инжектором комплекса ВЭПП-2000) позволит увеличить энергию частиц в БЭП от 0,9 до 1 ГэВ. ВЧ-система работает на частоте 174 МГц и состоит из ускоряющего резонатора, ВЧ-генератора мощности и системы управления. Нова ВЧ-система накопичувача БЕП (що є інжектором комплексу ВЕПП-2000) дозволить збільшити енергію частинок БЕП від 0,9 до 1 ГеВ. ВЧ-система працює на частоті 174 МГц і складається з прискорюючого резонатора, ВЧ-генератора потужності і системи управління. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Элементы ускорителей Status of 174 Mhz RF system for BEP ВЧ-система 174 Мгц накопителя БЭП ВЧ-система 174 Мгц накопичувача БЕП Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
Status of 174 Mhz RF system for BEP |
| spellingShingle |
Status of 174 Mhz RF system for BEP Biryuchevsky, Yu.A. Gorniker, E.I. Kendjebulatov, E.K. Krutikhin, S.A. Kurkin, G.Ya. Petrov, V.M. Pilan, A.M. Элементы ускорителей |
| title_short |
Status of 174 Mhz RF system for BEP |
| title_full |
Status of 174 Mhz RF system for BEP |
| title_fullStr |
Status of 174 Mhz RF system for BEP |
| title_full_unstemmed |
Status of 174 Mhz RF system for BEP |
| title_sort |
status of 174 mhz rf system for bep |
| author |
Biryuchevsky, Yu.A. Gorniker, E.I. Kendjebulatov, E.K. Krutikhin, S.A. Kurkin, G.Ya. Petrov, V.M. Pilan, A.M. |
| author_facet |
Biryuchevsky, Yu.A. Gorniker, E.I. Kendjebulatov, E.K. Krutikhin, S.A. Kurkin, G.Ya. Petrov, V.M. Pilan, A.M. |
| topic |
Элементы ускорителей |
| topic_facet |
Элементы ускорителей |
| publishDate |
2012 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
ВЧ-система 174 Мгц накопителя БЭП ВЧ-система 174 Мгц накопичувача БЕП |
| description |
The new RF system for the BEP storage ring (which is an injector of VEPP-2000 accelerating complex) will increase the particles energy in the BEP from 0.9 to 1 GeV. RF system operates at a frequency of 174 MHz and consists of an accelerating cavity, RF power generator and control system.
Новая ВЧ-система накопителя БЭП (являющегося инжектором комплекса ВЭПП-2000) позволит увеличить энергию частиц в БЭП от 0,9 до 1 ГэВ. ВЧ-система работает на частоте 174 МГц и состоит из ускоряющего резонатора, ВЧ-генератора мощности и системы управления.
Нова ВЧ-система накопичувача БЕП (що є інжектором комплексу ВЕПП-2000) дозволить збільшити енергію частинок БЕП від 0,9 до 1 ГеВ. ВЧ-система працює на частоті 174 МГц і складається з прискорюючого резонатора, ВЧ-генератора потужності і системи управління.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/108664 |
| citation_txt |
Status of 174 Mhz RF system for BEP / Yu.A. Biryuchevsky, E.I. Gorniker, E.K. Kendjebulatov, S.A. Krutikhin, G.Ya. Kurkin, V.M. Petrov, A.M. Pilan // Вопросы атомной науки и техники. — 2012. — № 3. — С. 49-52. — Бібліогр.: 4 назв. — англ. |
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ISSN 1562-6016. ВАНТ. 2012. №3(79) 49
STATUS OF 174 MHz RF SYSTEM FOR BEP
Yu.A. Biryuchevsky, E.I. Gorniker, E.K. Kendjebulatov, S.A. Krutikhin, G.Ya. Kurkin,
V.M. Petrov, A.M. Pilan
Budker INP, Novosibirsk, Russia
E-mail: Kendjebulatov@mail.ru
The new RF system for the BEP storage ring (which is an injector of VEPP-2000 accelerating complex) will in-
crease the particles energy in the BEP from 0.9 to 1 GeV. RF system operates at a frequency of 174 MHz and
consists of an accelerating cavity, RF power generator and control system.
PACS: 29.20.db
1. INTRODUCTION
Booster storage ring BEP is a part of the injector of
VEPP-2000 accelerator [1]. BEP is used to store elec-
tron and positron beams and to accelerate them up to the
energy of 0.9 GeV, before injection into the storage ring
VEPP-2000. The BEP upgrade program requires a re-
placement of the existing RF system (operating at a fre-
quency of 26.8 MHz − second harmonic of the revolu-
tion frequency) by a new one with operating frequency
of 174.4 MHz (13th harmonic of the revolution fre-
quency). The new booster RF system consists of an ac-
celerating cavity, RF generator and control system.
A coaxial accelerating cavity with maximum voltage
of 120 kV has mechanisms for tuning the fundamental
and higher order modes (HOM). Maximum output CW
power of RF generator is 20 kW. A GU-92A tetrode is
used in its output stage. Preliminary stages of the
generator are based on transistors. The control system
controls the amplitude and phase of the accelerating
voltage and provides synchronization for filling the ring
separatrixes. Parts of the RF system are in production
now.
2. ACCELERATING CAVITY
New cavity dimensions should not exceed the di-
mensions of the existing one, because the cavity will be
installed at the same location of the storage ring. Basic
requirements to the new BEP cavity are: operating fre-
quency − 174.4 MHz, accelerating voltage − about
110 kV, maximum RF power transferred to the beam −
about 14 kW.
The cavity design is shown in Fig.1.
3
1
2
4
4
5
5
6
7
8
9
33
11
22
44
44
55
55
66
77
88
99
Fig.1. BEP cavity design: 1 - bimetallic walls; 2 - coaxial inserts; 3 - cavity input coupler; 4 - main cavity tuners;
5 - cavity HOM tuners; 6 - sampling loop; 7 - vacuum pumping port; 8 - vacuum pump; 9 - cavity stand
ISSN 1562-6016. ВАНТ. 2012. №3(79) 50
The cavity has a cylindrical body (D = 600 mm,
L = 340 mm), consisting of a copper shell and bimetal-
lic (copper/stainless steel) walls (Fig.1, pos.1). Bimetal
design of the walls increases their mechanical stability
and reduces the sensitivity of cavity geometry to atmos-
pheric pressure. Coaxial inserts (pos.2) are located
symmetrically at the cavity axis. This design allows to
lower the frequency of the operating mode and reduces
the number and influence on the beam of cavity higher
order modes (HOM). Central location, symmetry and
small size of the accelerating gap provide additional
reduction of the HOMs influence on the beam for those
HOMs with odd number of variations along the cavity
axis. Vacuum cavity wall − coaxial insert conflate-joints
contain additional copper rings that provide RF contact
between parts. Neighboring to joints areas are rounded.
As shown by power numerical simulation [2], these
roundings reduce the probability of multipactor dis-
charge in these parts.
Cavity operating frequency is tuned by two movable
plungers with gear boxes. These tuners are identical to
those used for the race-track microtron-recuperator cav-
ity [3]. They are located diametrically opposite (pos.4).
Maximum tuner immersion into the cavity is 20 mm.
Simulations show that at such tuner stroke and cavity
voltage not exceeding 120 kV, multipactor discharge at
this area does not build up. Maximum possible operat-
ing frequency tuning range is 1.2 MHz. This wide range
allows obtaining the desired range of operational tuning
(± 130 kHz) for various combinations of the plungers
positions and thus to make some preliminary detuning
of HOMs.
Additional HOM detuning is produced by the cavity
HOM tuners (pos.5). These elements are completely
identical to those used in the race-track microtron-
recuperator cavity also. Their locations provide maxi-
mum frequency shift of several first HOMs.
Cavity input coupler (pos. 3) is designed to transfer
to the cavity about 20 kW of RF power. Input coupler
loop sizes provide matching of fully beam loaded cavity
with 75-Ohm feeding line.
Table 1
BEP cavity parameters
Harmonic number 13
RF frequency (MHz) 174.3755
RF frequency tuning (kHz) ±130
Rτ2
cavity (MOhm) 1.4
Total current (A) 0.2
Beam energy (MeV) 1000
Energy loss/turn (keV) 69.2
RF voltage (kV) 112
Radiation power (kW) 13.8
Cavity RF losses (kW) 4.5
Total RF power (kW) 18.3
Preliminary baking of the cavity at a temperature of
150°C, and ion-getter vacuum pump PVIG-250 (250 l/s)
should provide cavity vacuum not worse than 10-7 Torr.
Cavity parameters are given in Table 1. At the mo-
ment cavity design is completed. Input coupler and cav-
ity body are being produced at BINP workshop.
3. RF GENERATOR FOR BEP STORAGE
RING
3.1. GENERAL PARAMETERS
OF THE RF GENERATOR
The required RF power of 20 kW for driving the RF
cavity in CW regime at a frequency of 174 MHz is pro-
vided by an RF generator. It consists of an output stage
with vacuum tube and a solid state preamplifier. The
design of the output stage with vacuum tube is based on
the design that is widely used at BINP in all generators
at frequencies of 180 MHz. The preamplifier can yield
output power up to 2 kW. The output stage is directly
connected to RF cavity through a 75 Ohm coaxial
feeder. Cavity gap voltage is changed by adjusting the
drive signal at preamplifier input from 0 to 5 W. The
electric power for the generator is supplied from three-
phase network 380 V, it doesn’t exceed 50 kW.
In the output stage a water- and forced-air cooled
tetrode GU-92A is employed. The stage is made on
common-greed scheme. The tetrode works in a B class
with a cutoff angle about 100º. This decreases the effi-
ciency compared to the C class operation but improves
gain linearity at low input signal power level. For effec-
tive operation of automatic gain control system it is
necessary to eliminate any abrupt gain changes within
full range of the input signal levels.
Preamplifier is equipped with water cooling, and is
mounted inside a separate case which is fixed on a sup-
port of the output stage. DC power supplies for the out-
put stage and preamplifier are situated in separate cabi-
nets together with control, interlock, monitor and pro-
tection systems.
Basic requirements to DC power supplies and cool-
ing systems are summarized in Table 2.
Table 2
Basic requirements to DC power supplies and cooling
systems
Output RF power кВт 20
Anode DC voltage кВ 8
Anode DC current А 5
Screen grid voltage В +900
Screen grid current А 0,2
Bias voltage at 1-st grid В -(80…150)
1-st grid current А 0,1
Filament voltage (decreased) В 8,0
Filament current A 120
Cooling water flow rate l/min 40
Water pressure drop Bar 2.5
Cooling air flow rate m3/hour 400
At present time the output stage is assembled and
undergoes RF parameter measurements. Power supplies,
control, interlock, monitor and protection systems are
being prepared for switch on.
3.2. DESIGN OF THE OUTPUT STAGE
WITH GU-92А TETRODE
The equivalent circuit of the output stage is given in
Fig.2 at the left. On this scheme all locations of block-
ing capacitors С1-С14 are shown for reference; designa-
tions: F1, F2 – filament connections; C1, C2 – connec-
ISSN 1562-6016. ВАНТ. 2012. №3(79) 51
tions of the 1-st and 2-nd grids; Anode – anode output;
А-RF, C-RF – sensors of RF voltages on input and out-
put circuits; DC1 – directional coupler.
On the right part of Fig.2 there is a sketch of the
output stage design.
Common grid scheme is realized by RF shortening of
both grids via ceramic capacitors (5), and then by RF
shortening of screen grid current to the hull via ceramic
capacitors (18). Blocking ceramic capacitors (15) shorten
the anode circuit RF current to the hull of the stage.
Generator tetrode GU-92A (6) with water cooling
jacket (9) is designed as a quick-detachable unit.
Mounting and demounting of this unit is accomplished
by lever lift device (12).
The tuning of resonance frequency of anode circuit
is accomplished by air capacitor (7), the movable plate
of which is actuated by drive (8). Tuning range of the
anode circuit is 6 MHz.
The variable air capacitor (17) changes coupling co-
efficient between anode circuit and output coaxial
feeder going to the accelerating RF cavity. The coupling
may be adjusted by changing the gap by the drive (16).
Input circuit of the stage does not need operational
tuning. The required values of resonant frequency and
coupling coefficient with input coaxial 50-Ohm cable.
(19) are adjusted once during the first tuning by chang-
ing gaps of air capacitors – 23 and 20 correspondingly.
Fig.2. The equivalent circuit and design of the output stage
Resistor 200 W, 50 Ohm (21) is used for shunting
numerous resonant modes of the input circuit and pre-
amplifier in order to prevent self-excitation of the gen-
erator at frequencies much lower and much higher the
operational one (the experience shows that Q-factor
must be decreased to 10…100 in the frequency range of
20…1000 MHz).
Filament voltage is applied to the tube via connec-
tors (2) and elements of the input circuit (3). Two stages
of RF filters (1) weaken RF radiation from the generator
to an acceptable level. DC voltage is applied to screen
and control grids via RF filters (22). DC anode voltage
is supplied via RF filter (13) installed inside the support
of the output stage. Cooling water flows in and out
through pipes (10) made of insulating material.
4. CONTROL SYSTEM
The control system controls the amplitude and phase
of the 174 MHz cavity accelerating voltage. This system
is similar to the one currently in operation (Fig.3). The
system has three feedback loops. One of them controls
the cavity gap voltage amplitude by the cavity sampling
loop signal. To do this, the detected RF signal from the
loop is compared to the reference constant voltage (Vref)
by the error amplifier (EA). EA output signal regulates
the controlled amplifier (CA) transfer factor. The ampli-
tude of the RF cavity voltage is maintained proportional
to the reference voltage. Instability of the cavity RF
voltage amplitude does not exceed 0.3·10-3.
For the cavity frequency self-tuning the RF signal
from the cavity sampling loop and the signal from the
feeder sampling loop (which is proportional to the cur-
rent of the cavity input coupler loop) are fed to Phase
meter #2 (PM #2) input. The Phase meter output signal
controls the servo amplifier (SA), which is connected to
the cavity frequency tuning mechanism. A fixed phase
shift may be set by adjusting the external reference volt-
age. Phase control error does not exceed 5 degrees.
The third feedback loop provides a rigid binding of
the cavity RF voltage phase to the reference voltage
from the master generator. The Phase meter #1 (PM #1)
receives the cavity sampling loop signal and the refer-
ISSN 1562-6016. ВАНТ. 2012. №3(79) 52
ence RF voltage signal. The Phase meter output signal
controls the electronic phase shifter PS #1. Cavity RF
voltage phase instability does not exceed 0.5 deg rela-
tive to the reference RF signal. The phase shifters PS #2
and PS #3 are based on the commutated strip-lines and
used for the phase meters initial setup.
From BEP Master Oscillator
PS #1 CA
PM #1
PS #2
EA
PM #2 SAPS #3
RF amplifier
RF cavity
Vref.
Fig.3. Simplified block-diagram of RF system BEP
It is assumed in the new RF system, that the particles
will be injected into BEP from the cooling storage-ring
(CSR). This ring is a part of the injection complex VEPP-
5 [4], currently being commissioned. The CSR ring revo-
lution frequency is equal to 10.94 MHz. Before the injec-
tion, BEP revolution frequency will be tuned by the
phase-locked loop circuit (PLL) so that accelerators revo-
lution frequencies ratio is equal to FBEP / FCSR = 352/287.
Under this condition the bunch positions in both storage
rings are repeated with the frequency of greatest com-
mon divisor of their revolution frequencies − 38.1 kHz.
CSR deflector kickers and BEP inflector start from one
of the pulses that follow with this frequency. By adjust-
ing the delay of the BEP revolution frequency signal at
the PLL input, one can choose the number of the BEP
separatrix filled.
After filling of the BEP separatrix its revolution fre-
quency is controlled independently by a computer. Fur-
ther rise of the BEP particles energy follows. Before
injection of the particles into VEPP-2000, the revolution
frequencies of the rings are synchronizated by the
scheme which is similar to the one described above.
BEP revolution frequency is tuned again. The revolution
frequencies ratio is FBEP/FVEPP-2000 = 299/274. In order to
not excite the electron bunch phase oscillations in the
BEP, a provision has been made for correction of the
transient processes in the PLL circuit. In both cases,
after PLL circuits is switched on, BEP particles orbit
deviation from the optimal one is less than a few tenths
of a millimeter, which is quite acceptable.
Resolution and accuracy of injection into BEP and
VEPP-2000 is not worse than 50 ps. The control system
will partly use the old electronics. New modules are
being manufactured and tuned.
REFERENCES
1. Yu.M. Shatunov, et al. Project of a new electron-
positron collider VEPP-2000 // Proc. of EPAC 2000,
Vienna, Austria, 2000.
2. A.V. Grudiev, et al. Simulation of Multipacting in
RF Cavities and Periodical Structures // Proc. of
PAC 97, Vancouver, B.C., Canada, 1997.
3. N. Gavrilov, et al. RF Cavity for the Novosibirsk
Race-Track Microtron-Recuperator: Preprint Bud-
kerINP 94-92, Novosibirsk, 1994.
4. M.S. Avilov, et al. Status of VEPP-5 injection com-
plex // Proceedings of RuPAC XIX, Dubna, 2004.
Статья поступила в редакцию 23.09.2011 г.
ВЧ-СИСТЕМА 174 МГц НАКОПИТЕЛЯ БЭП
Ю.А. Бирючевский, Э.И. Горникер, Е.К. Кенжебулатов, С.А. Крутихин, Г.Я. Куркин,
В.М. Петров, А.М. Пилан
Новая ВЧ-система накопителя БЭП (являющегося инжектором комплекса ВЭПП-2000) позволит увели-
чить энергию частиц в БЭП от 0,9 до 1 ГэВ. ВЧ-система работает на частоте 174 МГц и состоит из уско-
ряющего резонатора, ВЧ-генератора мощности и системы управления.
ВЧ-СИСТЕМА 174 МГц НАКОПИЧУВАЧА БЕП
Ю.А. Бірючевський, Є.І. Горнікєр, Є.К. Кєнжебулатов, С.А. Крутіхін, Г.Я. Куркін,
В.М. Петров, А.М. Пілан
Нова ВЧ-система накопичувача БЕП (що є інжектором комплексу ВЕПП-2000) дозволить збільшити ене-
ргію частинок БЕП від 0,9 до 1 ГеВ. ВЧ-система працює на частоті 174 МГц і складається з прискорюючого
резонатора, ВЧ-генератора потужності і системи управління.
|