RF system of electron injector for the race-track microtron-recuperator and results of its operation with electron beam
The RF system is a part of the 1.6 - 2 MeV injector for the Race-Track Microtron - Recuperator (RTMR) that is under construction at BINP, Novosibirsk, for the Center of Photochemistry. RF system has three 180.4 MHz cavities. Buncher cavity operates at the accelerating voltage of 100 kV and two accel...
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| Veröffentlicht in: | Вопросы атомной науки и техники |
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| Datum: | 1999 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
1999
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| Zitieren: | RF system of electron injector for the race-track microtron-recuperator and results of its operation with electron beam / V. Arbuzov, N. Fomin, E. Gorniker, E. Kenjebulatov, A. Kondakov, S. Krutikhin, I. Kuptsov, G. Kurkin, S. Nosyrev, V. Osipov, V. Petrov, P. Piminov, I. Sedlyarov, A. Tribendis, V. Veshcherevich // Вопросы атомной науки и техники. — 1999. — № 4. — С. 26-28. — Бібліогр.: 5 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860118728521285632 |
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| author | Arbuzov, V. Fomin, N. Gorniker, E. Kenjebulatov, E. Kondakov, A. Krutikhin, S. Kuptsov, I. Kurkin, G. Nosyrev, S. Osipov, V. Petrov, V. Piminov, P. Sedlyarov, I. Tribendis, A. Veshcherevich, V. |
| author_facet | Arbuzov, V. Fomin, N. Gorniker, E. Kenjebulatov, E. Kondakov, A. Krutikhin, S. Kuptsov, I. Kurkin, G. Nosyrev, S. Osipov, V. Petrov, V. Piminov, P. Sedlyarov, I. Tribendis, A. Veshcherevich, V. |
| citation_txt | RF system of electron injector for the race-track microtron-recuperator and results of its operation with electron beam / V. Arbuzov, N. Fomin, E. Gorniker, E. Kenjebulatov, A. Kondakov, S. Krutikhin, I. Kuptsov, G. Kurkin, S. Nosyrev, V. Osipov, V. Petrov, P. Piminov, I. Sedlyarov, A. Tribendis, V. Veshcherevich // Вопросы атомной науки и техники. — 1999. — № 4. — С. 26-28. — Бібліогр.: 5 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | The RF system is a part of the 1.6 - 2 MeV injector for the Race-Track Microtron - Recuperator (RTMR) that is under construction at BINP, Novosibirsk, for the Center of Photochemistry. RF system has three 180.4 MHz cavities. Buncher cavity operates at the accelerating voltage of 100 kV and two accelerating cavities operate at the gap voltage up to 800 kV. Cavities are driven by 3 power amplifiers. Maximum output power of amplifier which feeds the accelerating cavity is 130 kW. Low level electronics controls phase and amplitude of RF cavity gap voltages and generates signals for synchronization of the electron gun. Maximum current of injector (45 mA) is realized at 22.5 MHz repetition rate of electron bunches. The effects of beam – RF cavities interaction and the RF system operation results are presented.
|
| first_indexed | 2025-12-07T17:38:27Z |
| format | Article |
| fulltext |
RF SYSTEM OF ELECTRON INJECTOR FOR THE RACE-TRACK
MICROTRON-RECUPERATOR AND RESULTS OF ITS OPERATION
WITH ELECTRON BEAM
V.Arbuzov, N.Fomin, E.Gorniker, E.Kenjebulatov, A.Kondakov, S.Krutikhin, I.Kuptsov,
G.Kurkin, S.Nosyrev, V.Osipov, V. Petrov, P.Piminov, I.Sedlyarov, A.Tribendis,
V. Veshcherevich
Budker Institute of Nuclear Physics, Novosibirsk, Russia
INTRODUCTION
The RF system is a part of the 1.6 - 2 MeV
injector for the Race-Track Microtron - Recuperator
(RTMR) that is under construction at BINP,
Novosibirsk, for the Center of Photochemistry. RF
system has three 180.4 MHz cavities. Buncher cavity
operates at the accelerating voltage of 100 kV and two
accelerating cavities operate at the gap voltage up to
800 kV. Cavities are driven by 3 power amplifiers.
Maximum output power of amplifier which feeds the
accelerating cavity is 130 kW. Low level electronics
controls phase and amplitude of RF cavity gap voltages
and generates signals for synchronization of the electron
gun. Maximum current of injector (45 mA) is realized at
22.5 MHz repetition rate of electron bunches. The
effects of beam – RF cavities interaction and the RF
system operation results are presented.
A 100 MeV, 45 mA CW race-track microtron-
recuperator (RTMR) is being built at Novosibirsk for a
free electron laser project [1]. The whole facility
includes a 1.6–2.0 MeV electron injector. It consists of a
300 keV electron gun, a buncher RF cavity and two
accelerating cavities. RF system has 3 separate
channels. Each of the channels includes one RF cavity,
RF power generator and a set of low-level control
electronics.
All cavities have the same operating frequency
which is equal to the frequency of the main RF system
of the RTMR (180.4 MHz). The RF voltage of the
buncher cavity is 100 kV, of each of the accelerating
cavities—800 kV.
A similar RF system was delivered by special order
to the research center KAERI, South Korea. It was
installed and tested there successfully.
CAVITY DESIGN
All cavities have a design similar to the design of
the RTMR cavities [2, 3]. The geometry of a cavity is
shown in Figure 1. Specifications of an accelerating
cavity are shown in the Table 1.
Cavities have copper clad stainless steel walls
(8 mm of copper and 7 mm of stainless steel). The
cylindrical wall and the side walls of the cavity are
joined to each other using TIG welding at stainless steel.
Good electrical connection of the walls is ensured by
copper. Parts are kept forced against each other due to
shrinkage of stainless steel in welds.
The schematic drawing of RF cavity with
insertion units is shown in Fig. 2. RF cavity is
connected to a 75 Ohm feeder line by a coupling loop.
The Al2O3 cylindrical ceramic window of the coupler
separates vacuum volume of RF cavity from
atmosphere.
Fig. 1. Geometry of RF cavity.
Table 1. Parameters of the cavity.
CW gap voltage (V) 0–950 kV
Q value 40,000
R/Q value 1 133.5 Ohm
Shunt impedance 1 5.3 MOhm
Resonance frequency 180.4 MHz
Tuning range of cavity frequency 320 kHz
Tuning rate 5 kHz/s
Wall loss P at V = 950 kV 85 kW
Maximal power flux at V = 950 kV 1.8 W/cm2
1 Shunt impedance R is defined as R = V 2/2P
There are two main tuners to control frequency
of fundamental E010 mode. Two special HOM tuners
are provided for correcting frequencies of HOMs which
may be excited by electron beam. These tuners have a
negligible effect on the fundamental mode. Resonance
frequencies of modes versus all tuner's position are
obtained from measurement of RF cavity at low power
level. Water is used to cool cavity body and insertion
units.
After completion of low level RF measurements
the cavities were closed, pumped out and baked out to a
temperature of about 300°C. A very high vacuum in the
cavity 10-8 - 10-9 Torr was obtained by means of an
effective pumping unit.
Before installation into an accelerator all cavities
were tested at a special high power test stand. The
buncher cavity was successfully tested to the
accelerating voltage of 600 kV, the accelerating cavities
were tested to the accelerating voltage of 1100 kV.
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 1999. № 4.
Серия: Ядерно-физические исследования (35), с. 26-28.
26
Fig. 2. RF cavity with insertion units.
RF POWER AMPLIFIERS
All RF power amplifiers were designed and
produced at BINP [4]. Two high power amplifiers
generate 130 kW of RF power each and drive
accelerating cavities. One low power amplifier (2 kW)
drives the buncher cavity. Each 130 kW amplifier has 3
stages. A modular design is used in the high power
output stage (Fig.3). The main module of the stage has a
tetrode tube GU-101A inside. At one side of this
assembly a tuner module is mounted. At the other side
of the assembly the load is connected through the
coupler module. A contactless design of the frequency
tuner and of the output coupler provides a high
reliability and absence of parasitic modulation. The
tuner is controlled remotely from control room.
RF power is transmitted from the stage output to
cavities through coaxial line 160/45 mm. The coupling
coefficient of the cavity coupler is adjusted so, that there
is no reflected power under maximum beam load
condition. VSWR in the line is less than 2.0 for lower
beam load.
Two preliminary stages of the 130 kW amplifier
employ tetrodes GU-92A in the grounded grid
configuration. RF power at input of the first stage does
not exceed 100 W and comes from a transistor
amplifier. Low power 2 kW amplifier has only one
GU-92A stage.
Water and air-cooling are used in power
amplifying units.
Tetrodes GU-101A and GU-92A are produces by
“Svetlana” firm-manufacturer in St.-Petersburg, Russia
[5].
air
RF power
output
3
1
water
+8 kV
1900
2
18
80
RF power
input
Fig. 3. Schematic drawing of power output stage.
1. Tetrode tube GU-101A. 2. Capacitance tuner.
3. Capacitance output coupler.
RF SYSTEM CONTROL
The simplified block-diagram of RF system
control is shown in Fig. 4. Master oscillator and
frequency divider generate reference and driving signals
for operation of 3 RF channels. All 3 channels are made
and work in a similar way.
Output 22 MHz
to electron gun
Master
oscillator
360.8 MHz
RF reference
180.4 MHz
Interlocks
Ifeed.
Vcav.
Frequency
divider RF cavity 1
Gain
control
Phase
shifter S1
Phasemeter 1
Divider
by 8
Modulator
Servo
amplifierPhasemeter 2
RF power amplifier
Phase
shifter S2
RF channel 1
RF channel 2
RF channel 3
HOM
Tuner
Fig. 4. Block-diagram of RF system control for injector
of microtron-recuperator.
There is a feed back loop to control amplitude of
cavity gap voltage. RF signal Vcav from the cavity
sampling loop comes into linear amplitude detector
input of the Modulator. Output of the amplitude detector
is connected to one of a differential amplifier inputs.
The reference DC voltage comes to another input of the
differential amplifier from computer controlled DAC.
Output of the differential amplifier controls gain of RF
amplifier. A gain of the differential amplifier is large
enough, so the cavity gap voltage is kept proportional to
the reference DC voltage.
The other feedback loop controls a phase of
cavity voltage. Phasemeter 1 measures phase difference
between the signal from cavity sampling loop and the
RF reference signal. Output of the phasemeter controls
the Phase shifter S1. It is possible to adjust the cavity
phase for normal acceleration of beam using Phase
shifter S2.
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 1999. № 4.
Серия: Ядерно-физические исследования (35), с. 26-28.
26
The reaction time of both feedback loops is
~300 µsec. Index of parasitic phase and amplitude
modulation is lower, than 2 • 10-3.
The resonance frequency of cavity should be
tuned continuously to compensate mostly for variation
of the cooling water temperature. The Phasemeter 2
measures the phase difference between RF voltage Vcav.
from cavity sampling loop and signal Ifeed from the
sampling loop in the feeder line. Signal from the latter
loop is proportional to the RF current of the cavity
coupling loop. Output of the Phasemeter 2 controls
cavity main tuner through the Servo amplifier. Reaction
time of the servo loop is ~100 msec, the accuracy is
~ 5 degr.
PRESENT STATUS OF RF SYSTEM
Presently adjustment of the Injector is going on.
Maximum beam current of 20 mA had been achieved at
electron energy of 1.5 MeV. The accelerating cavities
were operated at 700 kV of RF gap voltage. The total
RF power of 59 kW was consumed by one cavity. 12.5
kW of this amount was being transferred to the beam.
It is required that electrons should pass the
buncher cavity at the braking phase of RF voltage. For
beam current of 23 mA the energy transferred to the
cavity electromagnetic field from the beam is equal to
the cavity wall losses, so the energy consumed from RF
generator is zero.
In order to provide stable operation of RF system
at the total beam current range, the equivalent feeder
length between planes of equivalent representation of
the cavity and the anode of RF generator tube is equal to
odd number of a quarter wavelength. In that case the
anode current has a small variation in the total beam
current range for a given cavity voltage. The anode RF
voltage phase is reversed by 180° from initial position
for a beam current higher then 23 mA, so the excess of
energy from cavity is dissipated at anode of RF
generator tube.
For stable operation of the tuner servoloop, the
Phasemeter 2 (Fig. 4) is converted into the synchronous
detector.
REFERENCES
[1] V. Arbuzov et al. RF System of the CW Race-Track
Microtron-Recuperator for FELs. Proceedings of the
1993 IEEE Particle Accelerator Conference, Vol. 2,
pp. 1226–1228. Piscataway, NJ, 1993.
[2] N. Gavrilov et al. RF Cavity for the Novosibirsk
Race-Track Microtron-Recuperator. Preprint 94–92,
BINP, Novosibirsk, 1994. 24 p.
[3] V. Veshcherevich et al. RF Measurements and
Control of Higher Order Modes in Accelerating
Cavities. In: Proceedings of the 1995 Particle
Accelerator Conference, Vol. 3, pp. 1678–1680.
IEEE, Inc., Piscataway, NJ, 1996.
[4] E. Gorniker et al., RF System of VEPP-4M
Electron-Positron Collider. Proc. of the 1995
Particle Accelerator Conf., PAC–95, Vol. 3, p. 1681.
[5] Svetlana Corp., 194156 St. Petersburg, Russia.
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 1999. № 4.
Серия: Ядерно-физические исследования (35), с. 26-28.
26
|
| id | nasplib_isofts_kiev_ua-123456789-81519 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T17:38:27Z |
| publishDate | 1999 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Arbuzov, V. Fomin, N. Gorniker, E. Kenjebulatov, E. Kondakov, A. Krutikhin, S. Kuptsov, I. Kurkin, G. Nosyrev, S. Osipov, V. Petrov, V. Piminov, P. Sedlyarov, I. Tribendis, A. Veshcherevich, V. 2015-05-17T16:23:05Z 2015-05-17T16:23:05Z 1999 RF system of electron injector for the race-track microtron-recuperator and results of its operation with electron beam / V. Arbuzov, N. Fomin, E. Gorniker, E. Kenjebulatov, A. Kondakov, S. Krutikhin, I. Kuptsov, G. Kurkin, S. Nosyrev, V. Osipov, V. Petrov, P. Piminov, I. Sedlyarov, A. Tribendis, V. Veshcherevich // Вопросы атомной науки и техники. — 1999. — № 4. — С. 26-28. — Бібліогр.: 5 назв. — англ. 1562-6016 https://nasplib.isofts.kiev.ua/handle/123456789/81519 The RF system is a part of the 1.6 - 2 MeV injector for the Race-Track Microtron - Recuperator (RTMR) that is under construction at BINP, Novosibirsk, for the Center of Photochemistry. RF system has three 180.4 MHz cavities. Buncher cavity operates at the accelerating voltage of 100 kV and two accelerating cavities operate at the gap voltage up to 800 kV. Cavities are driven by 3 power amplifiers. Maximum output power of amplifier which feeds the accelerating cavity is 130 kW. Low level electronics controls phase and amplitude of RF cavity gap voltages and generates signals for synchronization of the electron gun. Maximum current of injector (45 mA) is realized at 22.5 MHz repetition rate of electron bunches. The effects of beam – RF cavities interaction and the RF system operation results are presented. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники RF system of electron injector for the race-track microtron-recuperator and results of its operation with electron beam ВЧ системы инжектора электронов разрезного микротрона-рекуператора и результаты его работы с электронным пучком Article published earlier |
| spellingShingle | RF system of electron injector for the race-track microtron-recuperator and results of its operation with electron beam Arbuzov, V. Fomin, N. Gorniker, E. Kenjebulatov, E. Kondakov, A. Krutikhin, S. Kuptsov, I. Kurkin, G. Nosyrev, S. Osipov, V. Petrov, V. Piminov, P. Sedlyarov, I. Tribendis, A. Veshcherevich, V. |
| title | RF system of electron injector for the race-track microtron-recuperator and results of its operation with electron beam |
| title_alt | ВЧ системы инжектора электронов разрезного микротрона-рекуператора и результаты его работы с электронным пучком |
| title_full | RF system of electron injector for the race-track microtron-recuperator and results of its operation with electron beam |
| title_fullStr | RF system of electron injector for the race-track microtron-recuperator and results of its operation with electron beam |
| title_full_unstemmed | RF system of electron injector for the race-track microtron-recuperator and results of its operation with electron beam |
| title_short | RF system of electron injector for the race-track microtron-recuperator and results of its operation with electron beam |
| title_sort | rf system of electron injector for the race-track microtron-recuperator and results of its operation with electron beam |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/81519 |
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