Formation of localised electron flow inside an interaction region of relativistic magnetron
For an increasing of the efficiency of relativistic magnetrons it is very important to prevent the axial drift of electrons away from an interaction region and the generation of a parasitic e-beam at the end of a cathode, which does not take part in energy exchange between electrons and waves at al...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2004
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| Назва видання: | Вопросы атомной науки и техники |
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| Цитувати: | Formation of localised electron flow inside an interaction region of relativistic magnetron / A.V. Agafonov, A.N. Lebedev, E.G.Krastelev // Вопросы атомной науки и техники. — 2004. — № 2. — С. 132-134. — Бібліогр.: 5 назв. — англ. |
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irk-123456789-793672015-04-01T03:02:16Z Formation of localised electron flow inside an interaction region of relativistic magnetron Agafonov, A.V. Lebedev, A.N. Krastelev, E.G. Динамика пучков For an increasing of the efficiency of relativistic magnetrons it is very important to prevent the axial drift of electrons away from an interaction region and the generation of a parasitic e-beam at the end of a cathode, which does not take part in energy exchange between electrons and waves at all. A special driver for double-sided powering of relativistic magnetrons and several methods of localised electron flow forming in the interaction region of relativistic magnetrons are proposed and discussed. Two experimental installations are presented and discussed. One of them is designed for laboratory research and demonstration experiments at rather low voltage. Another one is a prototype of a full-scale installation for an experimental research at relativistic levels of voltages on the microwave generation in the new integrated system consisting of a relativistic magnetron and symmetrical induction driver. Обговорюються підходи до формування локалізованого електронного потоку в області взаємодії релятивістського магнетрона з метою збільшення його ефективності. Для запобігання виносу електронного потоку з області взаємодії пропонується використовувати запропоновану раніше схему симетричного живлення і різні методи локалізації електронного потоку в області взаємодії. Приведено опис двох установок, одна з яких розрахована на проведення демонстраційних досліджень на невисокому рівні напруги, друга – являє собою прототип повномасштабної установки для проведення досліджень по генерації Свч-излучения при релятивістських напругах у пропонованій інтегрованій системі. Обсуждаются подходы к формированию локализованного электронного потока в области взаимодействия релятивистского магнетрона с целью увеличения его эффективности. Для предотвращения выноса электронного потока из области взаимодействия предлагается использовать предложенную ранее схему симметричного питания и различные методы локализации электронного потока в области взаимодействия. Приведено описание двух установок, одна из которых рассчитана на проведение демонстрационных исследований на невысоком уровне напряжения, вторая – представляет собой прототип полномасштабной установки для проведения исследований по генерации СВЧ-излучения при релятивистских напряжениях в предлагаемой интегрированной системе. 2004 Article Formation of localised electron flow inside an interaction region of relativistic magnetron / A.V. Agafonov, A.N. Lebedev, E.G.Krastelev // Вопросы атомной науки и техники. — 2004. — № 2. — С. 132-134. — Бібліогр.: 5 назв. — англ. 1562-6016 PACS: 29.25.Bx http://dspace.nbuv.gov.ua/handle/123456789/79367 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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English |
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Динамика пучков Динамика пучков |
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Динамика пучков Динамика пучков Agafonov, A.V. Lebedev, A.N. Krastelev, E.G. Formation of localised electron flow inside an interaction region of relativistic magnetron Вопросы атомной науки и техники |
| description |
For an increasing of the efficiency of relativistic magnetrons it is very important to prevent the axial drift of electrons away from an interaction region and the generation of a parasitic e-beam at the end of a cathode, which does
not take part in energy exchange between electrons and waves at all. A special driver for double-sided powering of
relativistic magnetrons and several methods of localised electron flow forming in the interaction region of relativistic magnetrons are proposed and discussed. Two experimental installations are presented and discussed. One of them
is designed for laboratory research and demonstration experiments at rather low voltage. Another one is a prototype
of a full-scale installation for an experimental research at relativistic levels of voltages on the microwave generation
in the new integrated system consisting of a relativistic magnetron and symmetrical induction driver. |
| format |
Article |
| author |
Agafonov, A.V. Lebedev, A.N. Krastelev, E.G. |
| author_facet |
Agafonov, A.V. Lebedev, A.N. Krastelev, E.G. |
| author_sort |
Agafonov, A.V. |
| title |
Formation of localised electron flow inside an interaction region of relativistic magnetron |
| title_short |
Formation of localised electron flow inside an interaction region of relativistic magnetron |
| title_full |
Formation of localised electron flow inside an interaction region of relativistic magnetron |
| title_fullStr |
Formation of localised electron flow inside an interaction region of relativistic magnetron |
| title_full_unstemmed |
Formation of localised electron flow inside an interaction region of relativistic magnetron |
| title_sort |
formation of localised electron flow inside an interaction region of relativistic magnetron |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2004 |
| topic_facet |
Динамика пучков |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/79367 |
| citation_txt |
Formation of localised electron flow inside an interaction region of relativistic magnetron / A.V. Agafonov, A.N. Lebedev, E.G.Krastelev // Вопросы атомной науки и техники. — 2004. — № 2. — С. 132-134. — Бібліогр.: 5 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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AT agafonovav formationoflocalisedelectronflowinsideaninteractionregionofrelativisticmagnetron AT lebedevan formationoflocalisedelectronflowinsideaninteractionregionofrelativisticmagnetron AT krasteleveg formationoflocalisedelectronflowinsideaninteractionregionofrelativisticmagnetron |
| first_indexed |
2025-07-06T03:26:23Z |
| last_indexed |
2025-07-06T03:26:23Z |
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1836866479453110272 |
| fulltext |
FORMATION OF LOCALISED ELECTRON FLOW INSIDE AN INTER-
ACTION REGION OF RELATIVISTIC MAGNETRON
A.V. Agafonov, A.N. Lebedev
Lebedev Physical Institute, Leninsky pr. 53, V-333, Moscow, GSP-1, 119991, Russia
E-mail: agafonov@sci.lebedev.ru, lebedev@sci.lebedev.ru,
E.G.Krastelev
Russian Research Centre “Kurchatov Institute”, Kurchatov Sq., Moscow, 123182, Russia
E-mail: krastelev@nfi.kiae.ru
For an increasing of the efficiency of relativistic magnetrons it is very important to prevent the axial drift of elec-
trons away from an interaction region and the generation of a parasitic e-beam at the end of a cathode, which does
not take part in energy exchange between electrons and waves at all. A special driver for double-sided powering of
relativistic magnetrons and several methods of localised electron flow forming in the interaction region of relativist-
ic magnetrons are proposed and discussed. Two experimental installations are presented and discussed. One of them
is designed for laboratory research and demonstration experiments at rather low voltage. Another one is a prototype
of a full-scale installation for an experimental research at relativistic levels of voltages on the microwave generation
in the new integrated system consisting of a relativistic magnetron and symmetrical induction driver.
Work supported by RFBR under grant No. 03-02-17300.
PACS: 29.25.Bx
1. INTRODUCTION
The high efficiency of "ordinary" classic magnetrons
has been achieved as a result of intense experimental
and theoretical investigations [1,2]. Relativistic magnet-
rons, in spite of a 20-year history of development, are in
an "initial" stage. The main purpose of experimental in-
vestigations was the demonstration of achievement of
extremely high RF-power [3,4]. Most results were ob-
tained using high-current accelerators in existence as
drivers, but not specialised drivers.
Actually RM generators were adapted for use with
those drivers and looked like an additional part to alien
drivers. However, achieved levels of pulsed power ex-
ceeding several GW are attractive, though the efficiency
of RM is low as compared with low voltage classic
magnetrons.
It appears that one way of increasing the efficiency
of RM is symmetric powering of RM that suppresses
parasitic beam current in the longitudinal direction, i.e.,
the construction of a specialised driver for this purpose.
2. BEAM FORMATION
The main idea of symmetric powering is rather clear
and will not be discussed here. Investigations of beam dy-
namics inside a simple model of a smooth-bore RM were
carried out with 2.5-D electromagnetic PIC-code KARAT
[5]. Calculations were carried out for 2-D r-z-geometry un-
der condition of azimuthal symmetry of considered mod-
els. Usual scheme of an electron beam formation in a mag-
netically insulated diode is illustrated in Fig.1.
It is suggested that the diode is powered from the
left side. Emitted electrons form a dense cloud inside
the gap. Self-electric field of the cloud push out elec-
trons to forward and backward longitudinal directions.
Backward flow of electrons is reflected by an electro-
static mirror, which is formed by increased radius of the
cathode stem. A beam reaching an anode is formed un-
der the action of longitudinal electric field at the upper
end of the cathode and azimuthal magnetic field Bθ of a
current flowing along the stem.
Fig.1: Formation of a beam in a magnetically insulated
diode
The direction of a drift velocity of electrons (vz ∝
vrBθ) coincides with the direction of Pointing's vector.
The presence of longitudinal electric field of opposite
direction counteracts drift motion in forward directions
and can lead to formation of backward electron flow
even for one-sided powering. The situations where ac-
celerating fields exist at both edges of a cathode are
shown in Fig.2.
Fig.2: Configurations of electron flows for double sided
(below) and one-sided powering (above)
___________________________________________________________
PROBLEMS OF ATOMIC SIENCE AND TECHNOLOGY. 2004. № 2.
Series: Nuclear Physics Investigations (43), p.132-134. 132
In this figure configurations of electron flows inside a
coaxial diode with an insertion (cathode) are presented
under conditions of symmetric and non-symmetric
powering. In the latter case a TEM-wave is launched
through the left side of the diode. The diode is embed-
ded in a longitudinal magnetic field of 8 kGs. A maxim-
um voltage of 500 kV and maximum emission current
of 10 kA were taken in the calculations.
Fig.3: Configurations of electron flows for double-sided
powering with magnetic bumps (above) and electrostat-
ic bumps (below)
Fig.3 illustrates two possible methods of localising
electron flow within the interaction region: use of sym-
metric magnetic bumps or electrostatic mirrors on both
sides of the diode, under condition of symmetric power-
ing. In the latter case the electrostatic mirrors are
formed by curved coaxial electrodes embedded in a lon-
gitudinal magnetic field.
Fig.4: Phase maps (pθ, r) of electron flows for double-
sided powering with magnetic bumps (above) and elec-
trostatic bumps (below)
Variation of magnetic field distribution and/or shape
of electrodes permit to form a desirable geometry of
electron flow. Comparison of characteristics of flows in-
side diodes with magnetic and electrostatic bumps
shows that the scheme with electrostatic bumps is
preferable for RM (see Fig.4).
3. INDUCTION DRIVER
From our point of view a symmetric induction driver
corresponds to a certain extent the idea of two-sided
powering of RM. Fig.5 shows the scheme of such a
driver integrated with a magnetron. The driver consists
of two identical sections of LIA (areas 1 and 2 in Fig.5)
Fig.5: Schematic of a driver
placed symmetrically relative to the magnetron (area 3)
and connected with a magnetron by a common central
electrode - the voltage adder. Both ends of the central
electrode join to flanges, which are at ground potential.
The central part of the electrode performs as the RM
cathode. This inner electrode adds the voltages from the
inductively insulated cavities (inductors) and delivers
the power to a high voltage anode-cathode gap of a
magnetron. Inside the each of two LIA sections the
voltage is increased stepwise from zero level at the
grounded end of the electrode up to the maximum level
equal to the sum of the voltages from the all cavities of
the LIA section. The full voltage appears only across the
coaxial structure at the magnetron region. For identical
left and right LIA sections powered from one common
pulse generator, the total output voltage of the left and
right sections are the same. The power flow is also sym-
metric. A coaxial magnetron schematically shown in
Fig.5 consists of a central cylindrical cathode, multivane
resonant anode structure and insulating magnetic field
coils.
RF-power is led out through slots in resonators of
the magnetron to radial waveguides followed by short
matching sections – transformers of impedance. This
scheme has been successfully used in experiments with
pulsed high power RM [3,4].
Merits of the driver are the merits of LIA with a
voltage adder. Such schemes are broadly used in mod-
ern high-current accelerators (HERMES-III, COBRA
etc.). The inductive driver provides the high efficiency
of the energy transmission from the pulsed power gener-
ator to the load and does not contain the high voltage in-
sulator designed for full operating voltage. It is possible
___________________________________________________________
PROBLEMS OF ATOMIC SIENCE AND TECHNOLOGY. 2004. № 2.
Series: Nuclear Physics Investigations (43), p.132-134.133
to use a relatively low voltage per cavity and con-
sequently low voltage pulsed generators with low
voltage transmission lines between the generator and the
cavities. Furthermore, the symmetrical inductive driver
generates symmetric power flow in the magnetron re-
gion provided by powering of all inductive cavities from
one common pulsed power generator or in pairs - one
cavity of the left side LIA section and second one of the
right side section connected to the one of the set of sev-
eral pulsed power generators. Some of the cavities of
the LIA sections and some of the generators may be
used for the rough and the fine correction of the shape
and the amplitude of the resulting high voltage pulse
across a magnetron.
Symmetric induction driver consists of double the
number of inductive cavities compared with current in-
ductive drivers for the same output voltage. The larger
number of cavities leads to a larger driver, which needs
a more powerful pulsed power generator or generators
to compensate the energy lost in the second set of the
cavities. But all these disadvantages may be negligible
compared with the advantages of the higher efficiency
of a symmetric RM.
4. CONCLUSIONS
To realise the idea of two-sided powering of RM
we have developed two experimental installations. One
of them is designed for laboratory research and demon-
stration experiments at rather low voltage. Another one
is a prototype of a full-scale installation for an experi-
mental research at relativistic levels of voltages on the
microwave generation in the new integrated system con-
sisting of a relativistic magnetron and symmetrical in-
duction driver.
The choice is based on our wishes to construct a fa-
cility consisting of several modules with flexible trans-
mission lines between a pulsed generator and the induc-
tion cavities made from standard low-voltage coaxial
cables. The number of the cavities, type and parameters
of the pulsed power generator may be easily changed
depending on the current experimental programme.
REFERENCES
1. E.Okress (ed.). Crossed-field microwave devices.
Academic Press. N.Y., 1961.
2. W.Manheimer AIP Conference Proceedings No.
249. The physics of particle accelerators. (Eds. M.
Month, M. Dienes)// AIP 1992. v.2, p.1795.
3. J.Benford, H.Sze, D.Bromley, B.Harteneck Pro-
ceedings of the 6th International //Conference on
High-Power Particle Beams, Japan. 1986, v.2,
p.577.
4. J.Benford, H.Sze, W.Woo, R.R.Smith, B.Harteneck
Proceedings of the 7th International //Conference
on High-Power Particle Beams, German. 1988, v.2,
p.1359.
5. P.V.Kotetashwily, P.V.Rybak, V.P.Tarakanov, In-
stitute of General Physics: Preprint, 1991, Moscow,
Russia No.44.
ФОРМИРОВАНИЕ ЛОКАЛИЗОВАННОГО ЭЛЕКТРОННОГО ПОТОКА В ОБЛАСТИ
ВЗАИМОДЕЙСТВИЯ РЕЛЯТИВИСТСКОГО МАГНЕТРОНА
А.В. Агафонов, А.Н. Лебедев, Е.Г. Крастелев
Обсуждаются подходы к формированию локализованного электронного потока в области взаимодей-
ствия релятивистского магнетрона с целью увеличения его эффективности. Для предотвращения выноса
электронного потока из области взаимодействия предлагается использовать предложенную ранее схему
симметричного питания и различные методы локализации электронного потока в области взаимодействия.
Приведено описание двух установок, одна из которых рассчитана на проведение демонстрационных иссле-
дований на невысоком уровне напряжения, вторая – представляет собой прототип полномасштабной уста-
новки для проведения исследований по генерации СВЧ-излучения при релятивистских напряжениях в
предлагаемой интегрированной системе.
Работа выполнена при поддержке гранта РФФИ 03-02-17300.
ФОРМУВАННЯ ЛОКАЛІЗОВАНОГО ЕЛЕКТРОННОГО ПОТОКУ В ОБЛАСТІ ВЗАЄМОДІЇ
РЕЛЯТИВІСТСЬКОГО МАГНЕТРОНА
А.В. Агафонов, А.Н. Лебедєв, Е.Г. Крастелев
Обговорюються підходи до формування локалізованого електронного потоку в області взаємодії
релятивістського магнетрона з метою збільшення його ефективності. Для запобігання виносу електронного
потоку з області взаємодії пропонується використовувати запропоновану раніше схему симетричного
живлення і різні методи локалізації електронного потоку в області взаємодії. Приведено опис двох
установок, одна з яких розрахована на проведення демонстраційних досліджень на невисокому рівні
напруги, друга – являє собою прототип повномасштабної установки для проведення досліджень по генерації
Свч-излучения при релятивістських напругах у пропонованій інтегрованій системі.
Робота виконана за підтримкою гранта РФФИ 03-02-17300.
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