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A Tesla-type long-pulse generator with wide flat-top width based on a double-width pulse-forming line
Abstract
To produce pulses with good flat-top quality, pulse-forming lines (PFLs) have been widely used in the field of Tesla-type pulse generators. To shorten the physical length of the PFL, a double-width PFL (DWPFL) is proposed that doubles the output pulse width while maintaining flat-top quality. A repetitively 10 GW Tesla-type long-pulse generator producing pulses with flat-top width of about 110 ns was developed with a coaxial DWPFL to produce high-current electron beams. Electron beams of about 10 GW with flat-top widths of about 110 ns were obtained on a planar vacuum diode load. With this pulse generator and a C-band high-power microwave system, microwaves of ~2.2 GW power and full-width at half-maximum of 101 ns were generated. The experiment demonstrates the feasibility and ideal output waveform quality of the DWPFL.
... The basic features of pulse-forming lines and innovative ways of dimension reduction are analyzed. Our attention was focused on pulse extension, for which we further developed the fruitful idea of pulse width doubling [23] by using an additional, uncharged inner line. This approach The wave impedance of the PFL and the electric strength at its inner conductor (at diameter 2r1) can be written as: ρ = 60 Λ/ε 1/2 Ω, where Λ = ln(r2/r1); and ...
... Another method of increasing the matching efficiency (η up to unit) and the voltage pulse width is to insert additional uncharged lines into a PFL, such that its effective wave impedance will increase by an integer number k = 2, 3, . . . . Figure 3 shows a double-width forming line (DWFL) that comprises two seriesconnected lines L 0 , L 1 that are equal in electrical length T and wave impedance ρ [23]. At the time of switch operation, line L 0 is charged to U 0 , and line L 1 is uncharged. ...
... Another method of increasing the matching efficiency (η up to unit) and the voltage pulse width is to insert additional uncharged lines into a PFL, such that its effective wave impedance will increase by an integer number k = 2, 3, …. Figure 3 shows a double-width forming line (DWFL) that comprises two series-connected lines L0, L1 that are equal in electrical length T and wave impedance ρ [23]. At the time of switch operation, line L0 is charged to U0, and line L1 is uncharged. ...
The paper considers such modifications of an ordinary pulse-forming line (PFL) as double-width and triple-width forming lines (DWFL, TWFL) built around the PFL by nesting one and two additional uncharged lines, respectively, into its free volume inside the inner conductor of the PFL. The theoretical analysis is supported by simulation and experimental data, showing that the TWFL provides a 3-fold increase in the voltage pulse width and that it can be further increased by an arbitrary integer factor k. The results of the numerical simulations also show the electric field behavior and other features, including the edge effect in the TWFL. The proposed method opens up new opportunities for designing compact high-power microwace (HPM) sources.
... The typical generator of this kind was invented by Zhang et al., which can be found in Refs. [25][26][27] and can also be found in Ref. [28] by Rostov et al. ...
The concept of the coaxial cascade-line rectangular-pulse generator is put forward, the basic idea of which is to cascade two coaxial lines of equal impedance together and make one line turn around to let the two lines use a common middle tube. The obvious feature of this kind of generator is that it can form a rectangular pulse with a width of 4 times the electrical length of one line. Compared with the conventional single-tube generator, the total stored energy is doubled. Namely, the output pulse width of the coaxial cascade-line generator is doubled for the same output voltage, which is beneficial for miniaturization. The principle of the cascade pulse forming line is first introduced; then the coaxial cascade-line rectangular-pulse generator is suggested. The simulation results prove the feasibility of the cascade-line generators. Finally, the design of a Tesla-type generator with an output power of 20 GW and a pulse width of 40 ns is presented based on the coaxial cascade-line method.
Published by the American Physical Society 2025
... Their axial lengths were shortened by more than 50% compared with TPG1000. [17][18][19] However, there is still a gap between the practical requirements and the current status from the perspective of miniaturization and light-weight. Due to this, this article further explored the insulation properties and application technology of high-dielectric-constant energy-storage medium, employed a DPFL with higher permittivity liquid Midel 7131, significantly increasing the output pulse width and making the system more compact, optimized the design of the system structural parameters, and developed a set of light Review of Scientific Instruments ARTICLE pubs.aip.org/aip/rsi and small-size repeated-frequency pulsed power generators, such as TPG1000C, which would be introduced in this paper. ...
The Tesla-type pulsed power generator based on transformer oil is limited by volume and weight, which affects its suitability for mobile platforms. In this paper, a double-width pulse forming line (PFL) based on high-energy-density liquid medium Midel 7131 was designed, and a compact, high-repetitive pulsed power generator was developed. The structural and electrical parameters of the PFL with an outer diameter of 1000 mm were optimized to achieve the highest output power with a fixed load impedance of 60 Ω. This generator employed a double-width forming line, which has an output pulse width of four times of the electrical length of its external line, significantly increasing the output pulse width and making the system more compact. The generator could be finally enveloped with a size of 4 × 1.5 × 1.5 m³ and a weight of 4.7 tons. The experiment showed that the generator could operate reliably under the conditions of 15-GW peak power, 50-ns pulse width, 50-Hz repetition rate, and <1% voltage jitter. The X-band relatively backward wave oscillator driven by this generator yielded a favorable microwave, which demonstrated the high-power driving capability of the generator.
... This setup is a Tesla-type generator that is capable of delivering a voltage pulse with 3-μs rise time and 200-kV maximum amplitude with negative polarity. [11][12][13] The test switch can be charged by the Tesla transformer. The resistor used as a matched load is 50 Ω, and the maximum amplitude of the output current pulse is 2 kA. ...
Comparative measurements with high-pressure spark gaps (gas pressure: 0.2–0.9 MPa nitrogen, gap spacing 5 mm) are presented, one with a regular Bruce-profile polished graphite cathode (diameter 25 mm, thickness 8 mm) and the other with a microarray graphite cathode of equal dimensions. By microstructuring, a V-type graphite microarray is created by purpose-developed laser treatment of a plane graphite electrode. The microarray graphite cathode brings more initial plasma and then produces more initial electrons. It is beneficial for electron emission, which improves the stability of the switch breakdown. The experimental results are achieved at a gas pressure of 0.9 MPa and a 200-kV voltage pulse applied to the switch. With these parameters, the mean breakdown voltage is 91.7 kV, the minimum is 91.4 kV, and the mean relative standard deviation in breakdown voltage of the first 100 shots is 0.4%. Compared to a plane graphite cathode, the mean breakdown voltage is about 10% lower, and the mean relative standard deviation is reduced by more than 90%. The main result can be stated that microarray graphite cathodes are a suitable choice as electrodes for low-jitter high-pressure spark gaps.
... To accommodate the rapid development and wide application of pulsed power technology, the miniaturization and lightweight of pulse generators has drawn great attention. [10][11][12][13][14] To achieve the lightweight and miniaturization of pulse generators, an effective way is to develop miniaturized, lightweight, and modular pulse forming network (PFN)/pulse forming line (PFL) units by using high energy storage density materials, such as ceramics, micas, and dielectric films. A single PFN/PFL unit can generate quasi-square pulses, and their superposition in series can elevate the output voltage. ...
The miniaturization, lightweight, and solidification of pulse forming lines (PFLs) are of prime significance during the evolution of pulsed power technology. In this paper, an all-solid-state annular pulse forming line (APFL) based on film-insulated coaxial transmission lines is developed to generate fast-rise time quasi-square pulses. First, a coiled coaxial transmission line (CCTL) comprised of multilayer polypropylene films with outstanding insulating properties is constructed. It can withstand direct current voltages up to 200 kV, with a cross section diameter of 7.4 mm. In addition, in order to turn the pulse transmission direction from circumferential to axial, a compact insulated terminal with a 90° bend structure is designed for CCTL. Although single terminal inductance can slow down the rising edge of the output pulse, their parallel connection in an APFL can weaken such an effect. The APFL, with a characteristic impedance of 2.95 Ω and a transmission time of 13 ns, is composed of three CCTLs with six terminals, which can run over 100 thousand times under the pulse voltage of 75 kV. Finally, 15 series APFL modules are employed to assemble a multi-stage PFL for the Tesla-type pulse generator. When charged to a voltage of 1 MV, the mixed PFL consisting of a coaxial line and the multi-stage PFL outputs quasi-square pulses with a voltage amplitude, rise time, and width of 510 kV, 4 ns, and 41.5 ns, respectively, and the fluctuation of the flat top is about 6%.
... For example, the Sinus-series [1], [9] and the Radan-series [10] generators in Russia, the Tesla-type Pulsed Generator (TPG)-series [2], [7], [8], the Chinese High Pulse (CHP)-series [11], and the compact generators [12], [13] in China. Recent developments about this open-magneticcore Tesla-type generators include: multilayer-wire secondary winding [14], [15], low-jitter switches [16], [17], doublewidth pulse forming line (PFL) [18], [19], film-rolled coaxial PFL [20], [21], and capacitor-loaded pulse forming network (PFN) [5], [22]. A 5-GW generator adopting most of these new technologies was reported in [23]. ...
A copper-titanium-composite primary winding for Tesla transformer is proposed in order to enhance its mechanical strength. This winding comprises a thin copper board and a thin titanium board which are joined by vacuum brazing welding. The copper board is specially used to conduct the current, while the titanium board is specially used to enhance the mechanical strength. A copper-titanium-composite primary winding with an axial length of 1 m, a diameter of 0.6 m, and a total thickness of 0.6 mm was designed, fabricated, assembled, and tested in an open-magnetic-core Tesla transformer, which realizes a normalized voltage boosting factor of 0.865 and an energy transfer efficiency of 0.712.
... A series of Tesla-type pulsed power generators, i.e., TPG (Tesla-pulsed generator)-series generators with magnetic cores embedded in the pulse-forming line, have been developed at our institute. [1][2][3][4][5]21,26 Their values of λ 0 are usually in the range of 0.75-0.90. The MWL secondary winding used here had 2000 turns. ...
A compact multi-wire-layered secondary winding for the Tesla transformer was proposed by Zhao et al. [Rev. Sci. Instrum. 88(5), 055112 (2017)]. The basic idea is to wind multiple layers of a metal wire around a polymeric base tube. However, the lifetime of this type of winding is only about 200 000 pulses, and thus it fails to meet the requirement of a lifetime of 1 × 10 ⁶ pulses. In this study, two methods are developed to prolong the lifetime of this winding. One method involves replacing the original three-skin wire with a polytetrafluoroethylene (PTFE) wire. The results of small-scale experiments in different conditions show that the lifetime of the PTFE-covered copper wire is at least ten times longer than that of the three-skin wire. The other method involves improving the local structure of this winding. A strong mechanical stress is concentrated at the small end of the winding, and a highly intense electric field appears in this region, where both reduce the lifetime of the winding. Improving the local structure of the winding theoretically prolongs its lifetime by a factor of 4. Both methods were applied to the original secondary winding of a Tesla transformer and extended its theoretical lifetime by a factor of 40. The modified winding had a lifetime longer than 2 × 10 ⁶ pulses without any traces of discharge. This is equivalent to a lifetime longer than that of the original winding by a factor of 10 and verifies the effectiveness of the proposed methods.
... The number 330 denotes the outer diameter (in mm) of the coaxial PFL. To lengthen the pulse, leaving the PFL length unchanged (1.3 m), the idea of a double-width PFL [28] was harnessed. In this case, the second line, having the same wave impedance as the first one and mounted inside the inner conductor, participates in the pulse formation. ...
This paper describes a recent activity in the development of a high-power microwave source based on a modified relativistic backward wave oscillator that is driven by an advanced version of a SINUS-family accelerator using a double-width pulse-forming line insulated with a modern synthetic oil. The relatively compact source of microwave pulses (0.6 GW, 20 ns, 9.4 GHz) can operate at a 100 pps repetition rate in a batch mode with batches of duration up to 15 s. The long-term stability of the oscillator performances during 106 pulses was achieved due to the improved conditions for explosive emission of the graphite cathode and the use of a titanium slow wave structure. Both factors prevented the shortening of the microwave pulses. With a proper choice of the magnetic field strength and longitudinal distribution and of the position of the resonant reflector, the pulse-to-pulse deviation of the microwave power was reduced with sacrifice in efficiency, which decreased from a simulated maximum efficiency of 44% to 40% in the simulation and to 35 ± 4% in the experiment. At an accelerating voltage of 418 kV and a magnetic induction of 0.64 T at the cathode, the standard deviation of the microwave pulsed power could be close to the voltage deviation.
... Recently, improvements have been made to the Tesla-type generator. For the Tesla transformer built in a pulse-forming line (PFL), the improvements include a multiwire-layered (MWL) secondary winding [1] and a double-width PFL [2], both of which can shorten the length of the PFL unit sharply. Improvements to the gas switch include the voltagedivision-type low-jitter self-triggered repetition-rate switch Manuscript received December 2, 2019; revised January 8, 2020; accepted January 21, 2020. ...
A multifunctional, long-lifetime, compact, and coaxial high-voltage (HV) vacuum insulator for Tesla-type generators is proposed for high-power microwave (HPM) generation. This vacuum insulator has two features. First, it is multifunctional since it can not only support the two conductors of the transmission line (TL), supply a vacuum environment for load, but also can eliminate a prepulse from the main pulse, which is realized via a grounded inductor. Second, it has a long lifetime. This feature is realized by optimizing the grounded inductor on the switch side and by grooving on the vacuum side. A 50-cm 700-kV compact coaxial HV vacuum insulator of such kind was designed, which was applied to a 1-MV Tesla-type generator to drive the relativistic backward-wave oscillator (RBWO) for HPM generation. Significantly, it has operated for a lifetime longer than 3,00,000 pulses at a repetition rate of 50 Hz without failure, which verifies the design.
... The X-band high power RBWO experiment is performed at the high-voltage accelerator TPG-1000X. 18 The experimental configuration is shown in Fig. 1. An annular graphite cathode is used with a blade thickness of 0.5 mm to emit the electron beam. ...
We found that the start time in microwave generation of a relativistic backward wave oscillator (RBWO) for a slowly rising voltage pulse demonstrates a large jitter, which can be explained by the spread of explosive electron emission thresholds and plasma formation rates of the explosive emission cathode, and this large jitter is reduced greatly by a weak external RF signal. So, the effects of the emission threshold and plasma formation rate on the oscillation start time of a single RBWO and on the phase synchronization in two parallel RBWOs are investigated using particle-in-cell simulations. The 2D simulations show that a larger emission threshold and a faster plasma formation rate lead to a shorter start time due to the stronger shock excitation provided by the sharper beam current leading edge. For some special emission thresholds, the start time is abnormally long, which is due to the generation of other frequencies because of the shock excitation. The 3D simulations illustrate that with a larger emission threshold and a faster plasma formation rate, phase synchronization can be obtained in two parallel RBWOs even for a large voltage rise time. Therefore, we expect that by choosing the appropriate cathode emission threshold and plasma formation rate, it is possible to realize phase stabilization of an RBWO for a slowly rising voltage pulse even without an external RF signal.
Based on two lines, a switch, and a load, four types of pulse generators can form, which are the single-line generator, the Blumlein-line generator, the double-width-line (DWL) generator, and the cascade-line generator. All these four types of generators have the planar forms and the coaxial forms. In addition, they can be folded to halve the total length. In this article, these four types of generators are reviewed, simulated, and compared. In addition, two kinds of novel folded coaxial rectangular-pulse generators are proposed.
The scheme of a resonant relativistic backward wave oscillator (BWO) was proposed by the group of researchers from IHCE SB RASfor efficient generation of high-power microwave radiation in the S-band while maintaining relatively small structure length about 2.5 λ. As far as can being found from publications, the scheme proposed uses high-current relativistic electron beams with energies of 0.7–1.5 MeV and a strong guiding magnetic field (at least 1.5 T, typically 2–3 T). In this paper, we propose a variant of a resonant relativistic backward wave oscillator that operates at moderately relativistic beam energies (450–550 keV) and at guiding magnetic field values starting from 1.3 T. Compared to the original resonant BWO geometry, in the current investigated scheme, the length of the periodic structure is increased by 1 period. For optimization using particle-in-cell code XOOPIC, the length of the insert between the cutoff-neck and the periodic structure, as well as the profiles of two terminal corrugations (defining the reflections from boundaries of periodic structure) are varied. It is shown in the numerical simulation that for a beam energy of 500–550 keV the average radiation power in proposed RBWO reaches level of 1 GW and efficiency is up to 27–28%.
A quasi-coaxial high-voltage (HV) rolled pulse forming line (rolled PFL) is researched in this paper. The PFL is rolled n circles on a support cylinder simultaneously by two layers of copper foil electrodes and two layers of insulation dielectrics. The first circle of the two electrodes are elicited in opposite directions along the axis, acting as the quasi-coaxial output structure of the PFL, and the left n − 1 circles of the PFL form a complete rolled strip line of n − 1 circles. The rolled PFL is convenient to realize HV insulation and is able to output a pulse with good quality. Characteristic parameters of the PFL are designed theoretically. Besides, the pulse discharge process of the PFL is simulated by computer simulation technology (CST) modeling, and the simulation result verifies the correctness of theory design. Furthermore, a rolled PFL with a characteristic impedance of 4.4 Ω is developed. The test characteristic impedance of the developed PFL by the incident pulse method confirms to the theory design. The discharge voltage waveform with a full width at half maximum of 57 ns of the PFL is acquired, which has a rise time of 6.8 ns. The HV test of the rolled PFL is carried out, and a discharge current pulse with an amplitude of 7 kA is acquired when the PFL is charged to 70 kV. It is calculated that the developed PFL has an energy storage density of 2.5 J/l. A Tesla generator based on 13 stages of rolled PFLs is designed, which is expected to output a 450 kV pulse with a duration of 100 ns on a 40-Ω match load. The discharge waveform of the generator is simulated by the CST software. The simulative output pulse has a rise time of 5 ns, with a flattop jitter less than 5%.
Efficient generation regime with a high power output has been experimentally realized in a klystron-like relativistic backward wave oscillator, in which a modulation cavity is inserted between the slow wave structure to decrease the energy spread of modulated beam electrons, and an extraction cavity is employed at the end of the slow wave structure to further recover energy from the electron beam. At a guiding magnetic field of 2.2 T, a microwave pulse with power of 6.5 GW, frequency of 4.26 GHz, pulse duration of 38 ns, and efficiency of 36% was generated when the diode voltage was 1.1 MV, and diode current was 16.4 kA. When the diode voltage was 820 kV, efficiency up to 47% with microwave power 4.4 GW was also realized experimentally.
This paper presents a nanosecond periodically-pulsed generator based on a spiral line charged by means of a high-coupling Tesla transformer. At repetition rate of 100 p.p.s., 130 ns, 500-700 kV pulses were produced in a 100-150 Ω load.
The advent of pulsed power technology in the 1960s has enabled the development of very high peak power sources of electromagnetic radiation in the microwave and millimeter wave bands of the electromagnetic spectrum. Such sources have applications in plasma physics, particle acceleration techniques, fusion energy research, high-power radars, and communications, to name just a few. This article describes recent ongoing activity in this field in both Russia and the United States. The overview of research in Russia focuses on high-power microwave (HPM) sources that are powered using SINUS accelerators, which were developed at the Institute of High Current Electronics. The overview of research in the United States focuses more broadly on recent accomplishments of a multidisciplinary university research initiative on HPM sources, which also involved close interactions with Department of Defense laboratories and industry. HPM sources described in this article have generated peak powers exceeding several gigawatts in pulse durations typically on the order of 100 ns in frequencies ranging from about 1 GHz to many tens of gigahertz.
The emission threshold of explosive emission cathodes (EECs) is an important factor for beam quality. It can affect the explosive emission delay time, the plasma expansion process on the cathode surface, and even the current amplitude when the current is not fully space-charge-limited. This paper researches the influence of the emission threshold of an annular EEC on the current waveform in a foilless diode when the current is measured by a Rogowski coil. The particle-in-cell simulation which is performed under some tolerable and necessary simplifications shows that the long explosive emission delay time of high-threshold cathodes may leave an apparent peak of displacement current on the rise edge of the current waveform, and this will occur only when the electron emission starts after this peak. The experimental researches, which are performed under a diode voltage of 1 MV and a repetitive frequency of 20 Hz, demonstrate that the graphite
cathode has a lower emission threshold and a longer lifetime than the stainless steel cathode according to the variation of the peak of displacement current on the rise edge of the current waveform.
The High Power Microwave (HPM) technology has advanced tremendously in the last five decades. What started out as a mere passive tool in the form of radar for detecting airborne objects during the second world war, has grown to be an active vehicle that can influence and impact its target. Progress has been made in all fronts. The peak radiated power has gone up several orders of magnitude to several gigawatts, the efficiency has grown by a wide margin, and the total energy radiated for pulsed sources has grown to several hundreds of Jules per pulse. Major obstacles still exist. The number of sources that have already achieved one gigawatt or higher is too great to cover here. In what follows, we will briefly describe the sources that have radiated one gigawatt or higher with a pulselength of 300 ns or longer, and an rms efficiency of 10% or higher. We also address the obstacles lying ahead and suggest possible means of overcoming them. The sources presented are the Relativistic Klystron
Oscillator (RKO), the Magnetically Insulated Line Oscillator (MILO), and the Tapered Magnetically Insulated Line Oscillator (TMILO).
Recent experimental results of three kinds of long-pulse high-power microwave (HPM) sources operating in S-, C-, and X-bands are reported. The difficulties in producing a long-pulse HPM for the O-type Cerenkov HPM source were analyzed theoretically. In S- and C-bands, single-mode relativistic backward-wave oscillators were designed to achieve long-pulse HPM outputs; in X-band, because of its shorter wavelength, an O-type Cerenkov HPM source with overmoded slow-wave systems (D/λ ≈ 3) was designed to increase power capacity. In experi- ments, driven by a repetitive long-pulse accelerator, both S- and C-band sources generated HPMs with power of about 2 GW and pulse duration of about 100 ns in single-shot mode, and the S-band source operated stably with output power of 1.2 GW in 20-Hz repetition mode. The X-band source generated 2 GW microwaves power with pulse duration of 80 ns in the single-shot mode and 1.2 GW microwave power with pulse duration of about 100 ns in the 20-Hz repetition mode. The experiments show good per- formances of the O-type Cerenkov HPM source in generating repetitive long-pulse HPMs, especially in S- and C-bands. It was suggested that explosive emissions on surfaces of designed eletrodynamic structures restrained pulse duration and operation stability.
The pulse forming line (PFL) is the key part of the intense electron-beam accelerators (IEBA), which determines the quality and characteristic of the output beam current of the IEBA. Compared with the accelerator with traditional Blumlein line, an IEBA based on strip spiral Blumlein line (SSBL) can increase the duration of the output pulse in the same geometrical dimension. But the disadvantage of the SSBL is that the output voltage waveform at the matched load may be distorted, which influences the electron beam quality. In this paper, according to the electromagnetic theory, formulas for calculating the main electric parameters of SSBL (inductance, capacitance, transmission time, and characteristic impedance) are deduced. The effect of the geometric parameters of SSBL on the slowing coefficient is analyzed. The designed condition of SSBL for the output ideal voltage pulse in the matched load is obtained by theoretical analysis. Furthermore, the Karat code is used to simulate the output voltage waveform of SSBL on the matched load for different spiral angels. At last, a couple of contrastive experiments are performed on an electron-beam accelerator based on the SSBL with water dielectric. The experimental results agree with the theoretical and simulated results.
This article describes the principles of operation and the
parameters of the SINUS setups designed at the Institute of
High-Current Electronics, Siberian Division, Russian Academy
of Science, over the period from 1990 to 2002. A characteristic
feature of accelerators of the SINUS type is the use of coaxial
forming lines (in particular, with a spiral central conductor)
which are charged by a built-in Tesla transformer to produce
the accelerating high-voltage pulses. This ensures a reasonable
compactness and long lifetime of the setups.
Tesla transformers are widely used in short pulse, repetition pulsed power generators. In this paper, a high repetitive rate intense electron beam accelerator (IEBA) based on high coupling (~1) Tesla transformer, which consists of a primary charging system, coaxial pulse forming line (PFL) charged by Tesla transformer and gas spark switch is described, especially stressed on the high coupling Tesla transformer. By introducing magnetic core to enhance the coupling factor between the primary and secondary windings, the transformer is capable of producing high voltage pulse up to 1.4 MV in approximately 45 µs. A coaxial pulse forming line is closely attached to the transformer that the outer and inner magnetic cores are parts of the PFL's outer and inner conductors respectively. In addition, the parameters of the Tesla transformer and PFL are calculated, including the dimension of the PFL and Tesla transformer. Some experiment results showed that the IEBA is capable of producing electron beams of 300–700 kV/7–13 kA at repetitive rate 100 Hz, with the pulse width 35 ns. The maximal energy efficiency of the Tesla transformer is 83%.
An approach for producing a long pulse up to 100 ns is presented. The generator based on this approach consists of a Tesla transformer and a set of pulse-forming networks (PFNs). The Tesla transformer is used to charge pulse-forming lines (PFLs) and PFNs which are in parallel. When the voltage increases to a certain value, the main switch will close, and the PFLs and PFNs will discharge rapidly to the load. Therefore, a high-voltage long pulse is formed on the load. The amplitude of this pulse is dependent only on the charging voltage and the matching state between the load and the PFL (PFN). The pulsewidth is determined by the transmission time of the PFL and PFN. The rise time is determined by the working state of the main switch and the impedance of the PFL and is independent of the parameters of the PFN. The PFN is multistage and assembled in series. The single-stage PFN is formed with ceramic capacitors placed between two unclosed annular plates. The total series impedance is equal to the sum of every single-stage PFN's impedance. A nine-stage PFN is used in the generator, and the total impedance is 40 Omega. Experimental results show that a high voltage of an amplitude of 300 kV, current of 6.9 kA, and duration of 110 ns is obtained at a repetition rate of 10 Hz, with a rise time of approximately 7 ns.
Electrical Engineering High-Power Microwave Sources and Technologies A volume in the IEEE Press Series on RF and Microwave Technology Roger D. Pollard and Richard Booton, Series Editors Written by a prolific group of leading researchers, High-Power Microwave Sources and Technologies focuses primarily on the high-power microwave (HPM) technology most appropriate for military applications. It highlights the advances achieved from 1995 to 2000 as the result of a US Department of Defense (DoD) funded, $15 million Multidisciplinary University Research Initiative (MURI) program. The grant created a synergy between researchers in the DoD laboratories and the academic community, and established links with the microwave vacuum electronics industry, which has led to unprecedented collaborations that transcend laboratory and disciplinary boundaries. This essential reference provides the history, state-of-the-art, and possible future of HPM source research and technologies. The first alternative to the multiplicity of detailed applications-based HPM books and journal articles, this book familiarizes the reader with recent advances in this rapidly changing field. It presents a compendium of valuable information on HPM sources, representing significant enabling technologies, including beam and rf control, cathodes, windows, and computational techniques. The era of utilizing computational techniques to electronically design an HPM source prior to actually building the hardware has arrived. Gain insight into proven techniques and solutions that will enhance your source design. High-Power Microwave Sources and Technologies is an invaluable resource to researchers active in the field, faculty, graduate and post-graduate students. Special Note: All royalties realized from the sale of this book will fund the future research and publications activities of graduate students in the HPM field.
One of the major issues in high-power microwave device operation is pulse shortening, which often limits microwave pulses to less than 100 ns. This has been the focus of many studies on the long-pulse backward-wave oscillator (BWO) at the University of New Mexico. Previous diagnostics have indicated that significant plasma is produced by a graphite knife-edge or "cookie cutter" geometry cathode. This plasma caused the beam to expand radially to match the dimensions of the cutoff neck upon entrance into the slow-wave structure. This effect led to an impedance collapse at which point the microwave production ceased. In recent studies by Loza and colleagues, they have produced intense annular relativistic electron beams that maintain a stable cross section for 1-μs duration utilizing a disk cathode. Whereas the beams produced by Loza and colleagues were not used in microwave sources, we have incorporated such a disk cathode in a long-pulse relativistic BWO to study its effort on pulse shortening. This simple solution has led to an increase in pulselength and radiated microwave power up to a factor of two as compared to the "cookie cutter" cathode.
A repetitive X-band relativistic backward-wave oscillator (BWO) driven by a SINUS-881 accelerator is described. Relativistic electron beams with peak current of 5.4 kA and voltage of 610 kV at a repetition rate of 100 Hz were generated by the SINUS-881 and then guided through the corrugated waveguide by an axial magnetic field of 3.0 T produced by a superconducting magnet. An electron collector was used to collect the electron beams in order to mitigate the effect of secondary emission electrons and to prevent ionization and breakdown near the electron beam dump. This BWO produces a microwave pulse power of 1.1 GW at a 100-Hz repetition rate, a frequency of 9.38 GHz, a pulse duration of 23 ns, and a power transforming efficiency of 33%.
Thermionic valve circuits: United States
- A D Blumlein
Development of 20GW/100 Hz repetitive pulsed accelerator
- Peng
Repetitively pulsed high-current accelerators with transformer charging of forming lines
- G A Mesyats
- Korovin
- Sd
- A V Gunin
- Gubanov
- Vp
- Stepchenko
- P I Alekseenko
b) Development of 20GW/100 Hz repetitive pulsed accelerator
- J C Peng
- J C Su
- Zhang
- Xb
- L M Wang
- Pan
- Yf
- Guo
- Wh
- Fang
- Jp
- X Sun
- L Zhao
- Li
- Y Wang