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Note: A high-energy-density Tesla-type pulse generator with novel insulating oil
Review of Scientific Instruments
Abstract
A 10-GW high-energy-density Tesla-type pulse generator is developed with an improved insulating liquid based on a modified Tesla pulser—TPG700, of which the pulse forming line (PFL) is filled with novel insulating oil instead of transformer oil. Properties of insulating oil determining the stored energy density of the PFL are analyzed, and a criterion for appropriate oil is proposed. Midel 7131 is chosen as an application example. The results of insulating property experiment under tens-of-microsecond pulse charging demonstrate that the insulation capability of Midel 7131 is better than that of KI45X transformer oil. The application test in Tesla pulser TPG700 shows that the output power is increased to 10.5 GW with Midel 7131. The output energy density of TPG700 increases for about 60% with Midel 7131.
... 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. ...
... As to the parameters shown in Table II, the relative dielectric constant of Midel 7131 is about 3.2, the DC withstand voltage is greater than 70 kV, and the energy storage density is more than double. In Ref. 19, the breakdown voltage of the two insulating oils under the condition of a pulse time of 30-35 μs and an electrode spacing of 1 cm were measured. The result shows that the breakdown voltage of KI45X is 437 kV, and the breakdown voltage of Midel 7131 is 493 kV, which is 12.7% higher than KI45X. ...
... This value is conservative. According to the design and operating parameters of the SINUS-series and the TPG-series repeated-frequency pulsed power generators, 13-20 the breakdown electric field of Midel 7131 measured in the literature, 19,21 and the general requirements of the long-term reliable operation of the TPG1000C repetition frequency, the working electric field of the Midel 7131 insulating medium, Emax, should be 100 kV/cm (namely, the average working electric field of the inner conductor surface of the external line). The main electrical and structural parameters of the PFL for the design are shown in Table III. ...
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.
... For example, such a uid can be MIDEL 7131, which is a synthetic ester dielectric liquid designed to provide alternative to flammable mineral oil. Since the advent of MIDEL 7131 in the 1970s, liquid (with very low conductivity and higher permittivity ε ≈ 3.1, as well as supe oxygen and moisture stability) has gained an excellent reputation as an effective dielec not only in industrial high-voltage transformers, but also in pulsed power systems as w [14,34]. Besides the possibility of decreasing the PFL length by 17% at a specified pu width, MIDEL 7131 can provide a gain in the PFL outer dimension due to its high bre down strength Ebr and the stability of its electric parameters during long-term opera [35]. ...
... For example, such a liquid can be MIDEL 7131, which is a synthetic ester dielectric liquid designed to provide an alternative to flammable mineral oil. Since the advent of MIDEL 7131 in the 1970s, this liquid (with very low conductivity and higher permittivity ε ≈ 3.1, as well as superior oxygen and moisture stability) has gained an excellent reputation as an effective dielectric, not only in industrial high-voltage transformers, but also in pulsed power systems as well [14,34]. Besides the possibility of decreasing the PFL length by 17% at a specified pulse width, MIDEL 7131 can provide a gain in the PFL outer dimension due to its high breakdown strength E br and the stability of its electric parameters during long-term operation [35]. ...
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 transformer oil in TPG700 was replaced with Midel 7131 by the researcher from the Northwest Nuclear Research Institute, which increased the output power from 8 to 10.5 GW and increased the energy storage density by 60%. 23 Therefore, Midel 7131 was selected as the final liquid medium in this study. ...
One of the important research directions in pulse power technology is to increase power density and operational stability of compact high-power pulse transformers. In this paper, the research object is a high-power pulse transformer using combined insulation, and the operating characteristics are obtained using simulation and experiment methods. The experimental results show that the maximum output voltage of the transformer increases by 30% in the combined insulation. At the same time, the combined insulation transformers are safer and have better insulation holding capacity. Moreover, multiple breakdowns have less effect on the subsequent breakdown voltage of the combined insulation transformer. The average subsequent breakdown voltage after 30 breakdowns of combination insulated transformers is still higher than the first breakdown voltage of non-combined insulation transformers. In addition, the energy storage density of combined insulation transformers is ∼40% higher than that of non-combined insulation transformers because of the higher permittivity of Midel 7131 than transformer oil.
... Once the gas gap is switched on, both coaxial lines operate in series, doubling the pulse length and the wave impedance. The PFL was insulated with the MIDEL-7131 synthetic oil [29]. The measured duration of the voltage pulse corresponded to a permittivity of about 3.1. ...
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.
... A capacitive voltage divider is used to measure the diode voltage of an electron beam accelerator [4] in our laboratory. The sketch of the electron beam accelerator is shown in Fig. 9. ...
In this paper, a new match circuit of the capacitive divider is studied. Using the proposed match circuit, the signal measured by the capacitive divider will not be secondarily attenuated near the accelerator, and the secondary attenuation is done at the terminal end of the cable which is located in a shielding room with a good electromagnetic environment. So, the proposed circuit has a better anti-interference capability than the traditional terminal-end match circuit. The result of the theoretic analysis shows that the proposed match circuit is equivalent with the traditional terminal-end match circuit when the parameters of the circuit are well chosen. Rectangular pulse response of the proposed match circuit is tested based on an equivalent circuit. It shows that the proposed match circuit has a good pulse response characteristic for rectangular pulse with a rise time of 5 ns, and the output waveform of the match circuit has a flattop jitter less than 1%. The match circuit proposed in this paper is utilized to measure the diode voltage of the accelerator in our laboratory. It is found that the high-frequency interference on the output waveform measured by the new match circuit is much smaller than that measured by the traditional terminal-end match circuit, which proves that the match circuit proposed in this paper is an effective method for increasing the signal-to-noise ratio of capacitive divider for measurement of nanosecond-range HV pulse.
Pulsed power is a technology that is suited to drive electrical loads requiring very large power pulses in short bursts (high-peak power). Certain applications require technology that can be deployed in small spaces under stressful environments, e.g., on a ship, vehicle, or aircraft. In 2001, the U.S. Department of Defense (DoD) launched a long-range (five-year) Multidisciplinary University Research Initiative (MURI) to study fundamental issues for compact pulsed power. This research program is endeavoring to: 1) introduce new materials for use in pulsed power systems; 2) examine alternative topologies for compact pulse generation; 3) study pulsed power switches, including pseudospark switches; and 4) investigate the basic physics related to the generation of pulsed power, such as the behavior of liquid dielectrics under intense electric field conditions. Furthermore, the integration of all of these building blocks is impacted by system architecture (how things are put together). This paper reviews the advances put forth to date by the researchers in this program and will assess the potential impact for future development of compact pulsed power systems.
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.
A MHz repetitive and nanosecond pulsed power generator based on the semiconductor opening switch (SOS) is developed, in which the pulse compression unit utilizes several Radio Frequency (RF) MOSFETs and a saturable Linear Transformer Driver (LTD). The RF MOSFETs are employed to obtain the forward pumping current pulses with the duration of tens of nanoseconds; the saturable LTD is used to raise the pulse voltage, to compress the pulse width and to pump SOS reversely. The SOS assembly cuts off the reverse current in a few nanoseconds, leading to a narrow output pulse on an external load. The experimental results show that the amplitude of the output pulse on a 106 Ω resistive load is about 3.8 kV and the width is 2 ns. Due to the repetitive ability of the RF MOSFETs, the generator can operate at a repetitive frequency of higher than 4 MHz in burst mode.
The design and construction of a repetitive high-current pulsed accelerator-TPG700 is described in this paper. The accelerator consists of a Tesla transformer with 40 ohm build-in coaxial pulse forming line. The triggered high-pressure switch of TPG700 has the capability of conducting current of 17.5kA in 35ns' duration at 100 pps. The transformer was designed to operate at 1.4MV, when its primary capacitors were charged to approximately 1000V. Under the working state of 100pps, the jitter of breakdown of the switch voltages is lower than 1% on average. To enhance the overall efficiency of the pulser, resonant charging technology based on IGBTs was utilized. As the experimental results indicate, the total efficiency of the pulser, when measured on matched dummy load, is close to 75%. The experimental results indicate that in matching case, the output of 700kV, 17kA for 40Ω resistive load is obtained. Moreover, some experiments such as long lifetime cathode testing and high power microwave (HPM) generation using backward oscillator (BWO) have been conducted on TPG700.
Breakdown effects in water, observed predominantly in the 2-10-microsec time domain for applied electrical fields in the range 200-500 kV/cm are reported. The test apparatus built explicitly for water breakdown research is described. It is shown that Martin's relation is a good gross measure of breakdown in this time region.
The breakdown strength of a water dielectric capacitor system is significantly increased by moderate pressurization. Substantially increased breakdown stresses were also noted at longer charging times. The highest stresses observed correspond to stored energy densities over 1 megajoule per cubic meter. In addition, preliminary results of the operation of a low impedance coaxial pressurized water capacitor are discussed.
This paper discusses the applicability of statistics to a wide field of problems. Examples of simple and complex distributions are given.
Insulating oils can be used as dielectric materials in a wide range of high voltage applications. Most notable amongst these liquids are naphthenic mineral oils, which are used in elements of pulsed power systems, such as switches and capacitors. Dielectric liquids are also used as energy storage media in pulsed power systems. In this application the use of liquids with higher dielectric permittivities will allow high-density energy storage systems to be developed. A dielectric oil with an unusually high, static relative permittivity of ~15, THESO oil, has been recently developed by Tetra Corp. This paper compares the measured dielectric properties of three types of insulating liquids: Diala D (Shell Ltd), ester liquid MIDEL 7131 and the high permittivity oil THESO. The study includes measurements of their relative permittivities, their electrical conductivities and their impulse dielectric strength. The data obtained on the dielectric characteristics of these liquids will be important for the optimisation of their applications in high voltage and pulsed power systems.
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.
The insulator strength of the oil-immersed equipment is usually limited by surface flashover across the oil-solid surface. At the same time, the distributions of failure strengths have some statistical characteristics. In this paper, the flashover voltage electric strengths of several PMMA test samples are measured in transformer oil under nanosecond pulse voltage. Normal distribution is introduced to describe the statistical characteristics of the experimental data. The plot of the flashover dielectric strength on Weibull paper can also demonstrates the two-parameter Weibull distribution. The parameters of the distributions are presented and the more favorable distribution is discussed with the view of obtaining consistent results for the surface dielectric strength
This article is of a somewhat unusual nature, being a slightly edited version of an original unpublished note written in 1970. This was some 11 years after work started on modern short pulse power technology at Atomic Weapons Research Establishment (AWRE). Sandia found out about us in early 1964 and Tom Martin had built Hermes II before this note was written. I cannot remember why I wrote the note, but some of the general potentiality of the technology was becoming apparent. Most of the defense applications were clear after two or three years work. The note was designed as an overview to help general workers build small to medium-sized pulse power machines, so they could join in the fun. The note covers in broad outline the approaches then available and provides formulae and breakdown data of an adequate nature to do this. Great accuracy was not the aim since any builder would use safety factors. Since I understand that the invitation to publish this article is both technical and historical, the temptation to rewrite it from the point of view of the best available present data has been resisted. Consequently, while the breakdown data, etc., have not been modernized, the values given are still believed to be adequate for design purposes. However, better data and relations do exist and a very good summary of these, useful formulae, etc., is provided in, “Pulse Power Formulary,” by R.J. Adler [15].
A repetitive high-current pulsed accelerator-TPG700
- X Song
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The newest R&D progress of transformer oil with petroleum cycloparaffin base in china
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cycloparaffin base in china," Electr. Equip. 6(1), 1-11 (2005) (in Chinese).
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Y. Ushakov, Impulse Breakdown of Liquids (Springer, Tomsk, 2006).
Test method for dielectric breakdown voltage of insulating oils of petroleum origin using VDE electrodes
- Astm Standard