Relativistic magnetron of 8 mm waveband
The first experimental study of relativistic magnetron of 8 mm wavelength with diffraction microwave output
 has been produced. Data that compare experiment and simulation are considered. Проведено перші експериментальні дослідження релятивістського 8 мм магнетрону з дифракційним
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| Published in: | Вопросы атомной науки и техники |
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| Date: | 2008 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2008
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| Cite this: | Релятивистский магнетрон 8 мм диапазона / I.I.Magda, N.P. Gadetski, E.I. Kravtsova, V.D. Naumenko, S.S. Pushkaryev, S.N. Terekhin, A.S. Tishchenko // Вопросы атомной науки и техники. — 2008. — № 4. — С. 18-20. — Бібліогр.: 2 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860134017827864576 |
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| author | Magda, I.I. Gadetski, N.P. Kravtsova, E.I. Naumenko, V.D. Pushkaryev, S.S. Terekhin, S.N. Tishchenko, A.S. |
| author_facet | Magda, I.I. Gadetski, N.P. Kravtsova, E.I. Naumenko, V.D. Pushkaryev, S.S. Terekhin, S.N. Tishchenko, A.S. |
| citation_txt | Релятивистский магнетрон 8 мм диапазона / I.I.Magda, N.P. Gadetski, E.I. Kravtsova, V.D. Naumenko, S.S. Pushkaryev, S.N. Terekhin, A.S. Tishchenko // Вопросы атомной науки и техники. — 2008. — № 4. — С. 18-20. — Бібліогр.: 2 назв. — англ. |
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| container_title | Вопросы атомной науки и техники |
| description | The first experimental study of relativistic magnetron of 8 mm wavelength with diffraction microwave output
has been produced. Data that compare experiment and simulation are considered.
Проведено перші експериментальні дослідження релятивістського 8 мм магнетрону з дифракційним
виводом мікрохвильового сигналу. Запроваджено порівняння даних експерименту та чисельної моделі.
Попередні дослідження РМ вказали існування генерації у діапазоні 8 мм. Експериментальні дані збігаються
з розрахунковими значеннями для фокусуючого магнітного поля та енергії електронів, відповідно умовам
збудження коливань π/2-виду при довжині хвилі 8,4 мм, а також з результатами чисельного моделювання.
Змінення потужності 8 мм випромінювання дозволили зробити оцінку ККД РМ біля 0,4%.
Проведены первые экспериментальные исследования релятивистского 8 мм магнетрона с дифракционным выводом микроволнового сигнала. Приводится сравнение данных эксперимента и численной модели.
Предварительные исследования РМ показали наличие генерации в диапазоне 8 мм. Экспериментальные данные совпадают с расчетными значениями для фокусирующего магнитного поля и энергии электронов, соответствующими условию возбуждения колебаний π/2-вида при длине волны 8.4 мм, а также с результатами
численного 3D-моделирования. Измерение мощности 8 мм излучения позволило оценить КПД РМ около
0.4%.
|
| first_indexed | 2025-12-07T17:46:14Z |
| format | Article |
| fulltext |
RELATIVISTIC MAGNETRON OF 8 mm WAVEBAND
I.I. Magda1, N.P. Gadetski1, E.I. Kravtsova1, V.D. Naumenko2,
S.S. Pushkaryev1, S.N. Terekhin2, A.S. Tishchenko2
1National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
2Usikov Institute for Radiophysics and Electronics NASU; Kharkov, Ukraine
E-mail: magda@kipt.kharkov.ua
The first experimental study of relativistic magnetron of 8 mm wavelength with diffraction microwave output
has been produced. Data that compare experiment and simulation are considered.
PACS: 52.80.Pi
1. INTRODUCTION
To promote into the area of higher frequencies a de-
sign of relativistic magnetron (RM) should meet two in-
consistent requirements. The first is concerned to reduc-
tion of interaction space of an electron cloud and elec-
trodynamic structure (EDS) according to scaling, dCА =
1/2(dA-dC)~λ [1]. The second is caused by type of emis-
sion which is explosive for relativistic high-current elec-
tron devices. Last requirement rigidly regulates the in-
crease of dCА till the size at which the electrode plasma
expansion across the focusing magnetic field does not
impact the dynamics of parameters of diode system and
excitation conditions of EDS. For RM operating with
the pulse width of up to several hundreds of nanosec-
onds dCА should exceed 6…8 mm.
A diameter of the cathode also is the parameter cor-
responded to another pair of inconsistent conditions. It
is known, that the condition of magnetron excitation
(Buneman-Hartree) is defined by synchronism of drift
movement of an electron cloud in crossed electric and
magnetic fields, and slow electromagnetic wave of cho-
sen oscillation mode: vDR = Е0/В0 = vPH. Thus, lower ac-
celerations can be realized only at smaller electric
fields. However the electric field intensity in a coaxial
system that is great enough in RM, increases quickly
with reduction in the cathode diameter. To compensate
the drift speed increase, it is possible to increase the
magnetic field intensity (that is not always possible) or
increase the cathode diameter that leads usually to dC ≥
1 cm.
Apparently, there are very rigid restrictions on re-
duction of dimensions of the cathode and EDS of RM
which are the basic distinctive feature of these devices
in comparison with their non-relativistic analogues. It is
necessary to notice that for RM of a cm wave range
these differences are not dramatic that allows to demon-
strate the highest impulse power up to tens of gigawatt.
Thus, typical RM with EDS cross-section of tens of
square centimeters has small number of resonators
(N = 6-8) that reduces the start currents and noises, and
provides generation at one frequency.
A choice of excitation conditions and oscillation
mode of EDS becomes a key problem at transition into
mm wave lengths. Since the restrictions on the cathode
and EDS dimensions remain the same as for RM of cm
wavelength, a number of resonators N ≈ πdА/λ can
achieve of several tens. In this case, there is a danger for
strong mode competition, absence of pure oscillation
spectrum and stable generation. Apparently, during the
years, the listed circumstances prevented creation and
study of RM of mm wave length. The present work ad-
dresses to creation and, as authors are considered, to the
first experimental study of such a device.
2. EXPERIMENTAL SETUP
Studied RM has rather traditional design except for a
MW energy output (Fig.1).
1
3
2 4
5
6
7
8
9
Fig.1. Schematics of 8 mm RM. 1. Return current col-
lector. 2. Anode. 3. Cathode holder. 4. Cathode. 5. Out-
put horn. 6. Solenoid. 7. Rogowski coil. 8. Shunts of an-
ode and collector currents. 9. Capacitor divider
The slow-wave system of the magnetron is presented
by 40 identical resonators of a slot type located on pe-
riphery of the ring anode (dА=28 mm, L=12 mm). The
cathode (dC=12 mm) is a continuation of the cylindrical
leg connected to the vacuum output of HV forming line.
The cathode and anode of RM are located in the middle
of a long cylindrical overdimensional waveguide
(d=80 mm, L=600 mm). The focusing magnetic field in-
duction is of 1…6 кG. To avoid breakdowns at the MW
energy output a diffraction channel with the overdimen-
sional waveguide and milar window at the end face of
the waveguide is used. At the side of the output window
the EDS is connected to the horn antenna, and at the op-
posite side the ring tuning plunge is adjusted.
The magnetron was powers by a negative voltage
pulse U0=160 kV, I=3.5…4 kА, tP=40…45 ns (Fig.2)
submitted to the cathode.
The goal of preliminary experimental study was in-
vestigation of operational regimes of RM and depen-
_______________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2008. № 4.
Серия: Плазменная электроника и новые методы ускорения (6), с.18-20.
18
mailto:magda@kipt.kharkov.ua?
dence of the 8 mm signal intensity on the focusing mag-
netic field variation, Fig.3.
Fig.2. Plots of magnetron signals. 1. Diode net current.
2. Voltage. 4. 8 mm detector. 10 ns/div
B0, kG
Р M
W
, a
.u
.
Fig.3. Dependence of intensity of 8 mm signal on focus-
ing magnetic field inductance (U0 = 160 kV)
Simultaneously, registration of microwave signal
corresponded to cm wavelength was provided. Qualita-
tive data corresponded to the wavelengths of 8 mm,
3 сm, and 10 cm were obtained with the help of crystal
detectors. Quantitative characteristics of 8 mm signal
were obtained with the help of 6D13D vacuum diode.
3. EXPERIMENTAL DATA ANALYSIS
The first tests of the magnetron had shown that MW
generation conditions were not fulfilled during a whole
current pulse (see Fig.2). It is possible to assume that
this is caused by dense plasma formation around small-
size resonators of the EDS structure that disrupted the
generation process.
More detailed study of designed RM system (see
Fig.1) that consists of the overdimensional waveguide
and RM EDS gave evidences of the presence of two
types of radiation related to the magnetron and cy-
clotron radiation mechanisms. Radiation of 8 mm wave-
band was registered only in the case of the presence of
the resonator system. Removal of the RM EDS created
conditions for realization only of the last mechanism.
4. RESULTS OF EXPERIMENT
AND SIMULATION
To differentiate the radiation mechanisms the fre-
quencies of the exited electromagnetic waves corre-
sponded to Н0N modes were estimated only for the
overdimensional coaxial waveguide. These data can be
added by the results of 3D PIC simulation of the same
system excited at the electron cyclotron frequency and
its harmonics. These data show that in the area of opera-
tional В0=2…3.5 kG excitation of the overdimensional
coaxial waveguide realized due to the cyclotron mecha-
nism is possible in the range nwсе = 6…13 GHz (Fig.4).
This corresponds to the harmonic number n ≤ 2-3. It is
interesting to note that MW radiation which could meet
for higher n was not observed experimentally.
a)
b)
Fig.4. Frequency spectrums of Er (a) and Eθ (b) compo-
nents of Н0N modes excited in overdimensional coaxial
waveguide, d=12 mm, D=80 mm by means of electron
cyclotron oscillations. Results are produced with the use
of 3D simulation model based on CST Particle Studio [2]
A question of the excited oscillation modes still re-
mains without full enough experimental acknowledge-
ment. Nevertheless, a range of the magnetic field values
related to RM generation (see Fig.3) is in good corre-
spondence with estimated operational parameters which
meet for the conditions of excitation of π/2 oscillation
mode at λ = 8.4 mm.
Preliminary answer can be obtained at simulation of
electron trajectories and dynamics of electromagnetic
fields in RM using 3D electromagnetic PIC code [2].
The particle trajectories for the case U0 = 100 kV,
B0 =2…3.5 kG testify that the dense electron cloud
takes part in drift movement near the slow-wave struc-
ture, and bidirectional axial electron flow creates intense
losses of beam current. The electric field distribution of
the slow wave traveling around the EDS testifies to for-
mation of competing π/2 and π/3 modes that has not
complete correspondence to chosen conditions of exci-
tation of π/2 modes in the real system for U0 = 160 kV
and B0 = 2…3.5 kG.
The electron beam current distribution in studied
system plays important role in the magnetron operation.
Measurements of currents were carried out by a number
of probes, Fig.1. The net, anode and axial currents were
registered, accordingly, by the Rogowski coil 7, and
shunts established on periphery of the anode and collec-
tor flanges 8. Their values usually are of 3.5…4 kА,
50…100 A, and 600…1000 A, accordingly, that testi-
fies of significant beam current losses before the anode
block. Thus, one and the most significant loss channels
is geared to an axial return beam current which is inter-
cepted from one side by the return current collector 1.
The current losses of minor intensity (by a factor of
_______________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2008. № 4.
Серия: Плазменная электроника и новые методы ускорения (6), с.18-20.
19
~4 obtained experimentally) correspond to an axial
leakage of beam electrons as it is shown in Fig.5.
Fig.5. Electron trajectories in electrodynamic structure
of RM and overdimensional output waveguide
Measurements of intensity of the output radiation in
millimeter wave range was made with the help of horn
reception system and calibrated vacuum detector estab-
lished along an axis of the overdimensional waveguide
at different distances from the waveguide window. Con-
ditions of the detector calibration defined its tuning to
the wavelength of 8.26 mm. Ignoring possible differ-
ence in the wavelengths of calibrating and radiating sig-
nals it is possible to count, that the impulse power of
RM in preliminary experiments did not exceed
PMW = 48…52 kW.
The MW power efficiency of RM can be estimated
as a relation between measured MW power PMW, and
beam impulse power obtained from experimental data
of the anode current, PB = U0IА. For typical regimes
IА = 75 А, and PB = 12 MW, that gives the MW power
efficiency of RM of ~0.4%.
CONCLUSIONS
Preliminary study of first experimental variant of
RM demonstrated MW emission in 8 mm wave range.
Experimental data coincides with estimated ones for the
focusing magnetic field and electron energies that corre-
spond to the conditions of π/2 mode excitation at
λ = 8.4 mm and also in part to the results of 3D simula-
tion.
Measurement of the impulse power of MW emission
at 8 mm wavelength gives the efficiency of RM on pow-
er of ~0.4%. Further investigations of RM will be fo-
cused on improving the radiation efficiency by means of
eliminating the beam current losses in vacuum chamber.
REFERENCES
1. J. Benford, J. Swegle. High-Power Microwaves.
Artech House Inc, Boston, London. 1992, Ch.5,
412p.
2. CST Particle Studio. CST Studio Suite 2006. Com-
puter Simulation Technology, CST GmbH, Darm-
stadt, Germany.
Статья поступила в редакцию 30.05.2008 г.
РЕЛЯТИВИСТСКИЙ МАГНЕТРОН 8 мм ДИАПАЗОНА
И.И. Магда, Н.П. Гадецкий, Е.И. Кравцова, В.Д. Науменко, С.С. Пушкарев, С.Н. Терехин, А.С. Тищенко
Проведены первые экспериментальные исследования релятивистского 8 мм магнетрона с дифракцион-
ным выводом микроволнового сигнала. Приводится сравнение данных эксперимента и численной модели.
Предварительные исследования РМ показали наличие генерации в диапазоне 8 мм. Экспериментальные дан-
ные совпадают с расчетными значениями для фокусирующего магнитного поля и энергии электронов, соот-
ветствующими условию возбуждения колебаний π/2-вида при длине волны 8.4 мм, а также с результатами
численного 3D-моделирования. Измерение мощности 8 мм излучения позволило оценить КПД РМ около
0.4%.
РЕЛЯТИВІСТСЬКИЙ МАГНЕТРОН 8 мм ДІАПАЗОНУ
І.І. Магда, М.П. Гадецький, О.І. Кравцова, В.Д. Науменко, С.С. Пушкарьов, С.М. Терьохін, А.С. Тіщенко
Проведено перші експериментальні дослідження релятивістського 8 мм магнетрону з дифракційним
виводом мікрохвильового сигналу. Запроваджено порівняння даних експерименту та чисельної моделі.
Попередні дослідження РМ вказали існування генерації у діапазоні 8 мм. Експериментальні дані збігаються
з розрахунковими значеннями для фокусуючого магнітного поля та енергії електронів, відповідно умовам
збудження коливань π/2-виду при довжині хвилі 8,4 мм, а також з результатами чисельного моделювання.
Змінення потужності 8 мм випромінювання дозволили зробити оцінку ККД РМ біля 0,4%.
___________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2008. № 4.
Серия: Плазменная электроника и новые методы ускорения (6), с.
20
Output Waveguide
EDS
Drifting Electron Flow
Axial E-
Beam
|
| id | nasplib_isofts_kiev_ua-123456789-110283 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T17:46:14Z |
| publishDate | 2008 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Magda, I.I. Gadetski, N.P. Kravtsova, E.I. Naumenko, V.D. Pushkaryev, S.S. Terekhin, S.N. Tishchenko, A.S. 2017-01-02T21:31:50Z 2017-01-02T21:31:50Z 2008 Релятивистский магнетрон 8 мм диапазона / I.I.Magda, N.P. Gadetski, E.I. Kravtsova, V.D. Naumenko, S.S. Pushkaryev, S.N. Terekhin, A.S. Tishchenko // Вопросы атомной науки и техники. — 2008. — № 4. — С. 18-20. — Бібліогр.: 2 назв. — англ. 1562-6016 PACS: 52.80.Pi https://nasplib.isofts.kiev.ua/handle/123456789/110283 The first experimental study of relativistic magnetron of 8 mm wavelength with diffraction microwave output
 has been produced. Data that compare experiment and simulation are considered. Проведено перші експериментальні дослідження релятивістського 8 мм магнетрону з дифракційним
 виводом мікрохвильового сигналу. Запроваджено порівняння даних експерименту та чисельної моделі.
 Попередні дослідження РМ вказали існування генерації у діапазоні 8 мм. Експериментальні дані збігаються
 з розрахунковими значеннями для фокусуючого магнітного поля та енергії електронів, відповідно умовам
 збудження коливань π/2-виду при довжині хвилі 8,4 мм, а також з результатами чисельного моделювання.
 Змінення потужності 8 мм випромінювання дозволили зробити оцінку ККД РМ біля 0,4%. Проведены первые экспериментальные исследования релятивистского 8 мм магнетрона с дифракционным выводом микроволнового сигнала. Приводится сравнение данных эксперимента и численной модели.
 Предварительные исследования РМ показали наличие генерации в диапазоне 8 мм. Экспериментальные данные совпадают с расчетными значениями для фокусирующего магнитного поля и энергии электронов, соответствующими условию возбуждения колебаний π/2-вида при длине волны 8.4 мм, а также с результатами
 численного 3D-моделирования. Измерение мощности 8 мм излучения позволило оценить КПД РМ около
 0.4%. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Сильноточная релятивистская электроника Relativistic magnetron of 8 mm waveband Релятивістський магнетрон 8 мм діапазону Релятивистский магнетрон 8 мм диапазона Article published earlier |
| spellingShingle | Relativistic magnetron of 8 mm waveband Magda, I.I. Gadetski, N.P. Kravtsova, E.I. Naumenko, V.D. Pushkaryev, S.S. Terekhin, S.N. Tishchenko, A.S. Сильноточная релятивистская электроника |
| title | Relativistic magnetron of 8 mm waveband |
| title_alt | Релятивістський магнетрон 8 мм діапазону Релятивистский магнетрон 8 мм диапазона |
| title_full | Relativistic magnetron of 8 mm waveband |
| title_fullStr | Relativistic magnetron of 8 mm waveband |
| title_full_unstemmed | Relativistic magnetron of 8 mm waveband |
| title_short | Relativistic magnetron of 8 mm waveband |
| title_sort | relativistic magnetron of 8 mm waveband |
| topic | Сильноточная релятивистская электроника |
| topic_facet | Сильноточная релятивистская электроника |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/110283 |
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