Dielectric study of water/methanol mixtures for use in pulsed-power water capacitors

Abstract

Articles you may be interested inThe critical behavior of the dielectric constant in the polar + polar binary liquid mixture nitromethane + 3-pentanol: An unusual sign of its critical amplitude in the one-phase region J. Chem. Phys. 135, 024508 (2011); 10.1063/1.3607237 Temperature, concentration, and frequency dependence of the dielectric constant near the critical point of the binary liquid mixture nitrobenzene-tetradecane A ground level interpretation of the dielectric behavior of diluted alcohol-in-carbon tetrachloride mixtures Large pulsed-power systems normally use a solid capacitive primary storage and a water capacitor for secondary storage. It is shown that the electrical breakdown strength is increased and the maximum storage time is enhanced from the microsecond level to the millisecond level when the water is replaced by a water/methanol mixture. The increased time scale in the second storage enables the use of an inductive primary storage. The mixing of methanol in the water decreases the relative permittivity. However, due to the increased electrical breakdown strength, a higher energy density is nevertheless possible. Previous work with water/ethylene glycol has manifested the problem of charge injection that occurs when energy is stored for millisecond time scales at high electrical stress. Water/methanol mixtures show less tendency for charge injection and a better ability to store energy at millisecond time scales.

Water as an insulator in pulsed facilities (Review)

“…These measurements allowed the authors [59] to conclude that an H 2 O + methanol mixture is the insula-δ tan tor of choice for secondary storages charged in millisecond times. Although the maximum field E b = 125 kV/cm in this mixture is lower than E b = 160 kV/cm in the other, with allowance for the injection of a smaller number of ions into the methanol mixture, a storage unit with this insulation will be more efficient during charging and transferring the energy to the load, since the energy density A has a maximum of 74 × 10 -6 J s/cm 3 at -23°C.…”

“…The possibility of using "slower" (with a pulse duration of >300 µs) inexpensive electromechanical storages (synchronous ac generators or turbine-driven generators with forced excitation) or inductive storages (e.g., [58,59]) rather than voltage pulse generators as powerful intermediate high-voltage sources in highenergy-capacity EPFs with water insulation is often discussed in the literature. These storages have a higher stored energy density per unit volume than capacitor banks, thus allowing the dimensions and cost of an EPF to be reduced.…”

“…The electrical properties of water-methanol (CH 3 OH) mixtures were studied in [59]. The objective was to test the possibility of using this mixture as an insulator in a secondary low-impedance, high-voltage energy storage with an electrical length of ~40 ns; this allows a reduction in the energy loss during its charging for a few microseconds from an inductive storage with a superconducting coil made, in particular, from a new material, MgB 2 .…”

A Repetitive Low Impedance High Power Microwave Driver

“…They are suitable for driving high impedance (>50 Ω) HPM tubes such as the BWO [23] since the suitable for driving high impedance (>50 Ω) HPM tubes such as the BWO [23] since the oil insulated PFL has characteristic impedance in the range of dozens of ohms. For lower impedance (<20 Ω) requirements, water or aqueous based liquid mixture may be used as they have a higher dielectric constant than transformer oil [22,24]. Some other accelerators have no pulse forming lines, as they use a Marx generator or a linear transformer driver (LTD) with a very short rise time [14,15,21] or with a pulse forming network (PFN) [19,20], and the output pulse width is not limited by the geometry length of the driver.…”

Breakdown Characteristic Research on Propylene Carbonate After Nano-Modification

“…Propylene carbonate, with its great permittivity, high breakdown strength, and eco-friendly features, has a great potential in improving the compactness of pulsed power systems, while the strong polarity effect restricts further growth [13,14]. The polarity effect refers to the difference between positive and negative breakdown strengths.…”