Current Decay Rate Research Articles

Detection of inter turn fault in transformer windings by parameters of their transition processes

The proposed method of detection the inter turn fault of transformer windings relates to the area of defectoscopy and allows detecting inter turn faults in a wide range of damaged (closed) turns. Power and instrument transformers with iron-core are widely used in power networks. As the insulation ages or is damaged, the wires between various transformer sections short circuits occur, which inevitably leads to a complete damage of the transformer. Short- circuited part of the transformer forms an additional winding, the outputs of which are short- circuited. The transition process of current increasing when DC voltage is connected to the transformer outputs occurs in diverse ways in undamaged (cut-off) winding section and in the damaged (short-circuited) section. The current growth rate in the undamaged section of the winding is determined by high magnetization inductance. The inductance of the short-circuited part of the winding is much less, so, the current growth rate in the short-circuited part is significantly greater than the current growth rate in the undamaged part of the winding. The article presents observations from computer models and real measurements of the substation auxiliary power transformer, which show the possibility of determining the presence of a turn fault in regards to the transition process parameters, the rate of current increase and decay in the transformer winding. The device aimed to find the inter turn faults in the transformer windings, working according to the proposed method will be quite simple and have a high sensitivity.

A 3-3-1 model with low scale seesaw mechanisms

We construct a viable 3-3-1 model with two SU(3)_L scalar triplets, extended fermion and scalar spectrum, based on the T^{prime } family symmetry and other auxiliary cyclic symmetries, whose spontaneous breaking yields the observed pattern of SM fermion mass spectrum and fermionic mixing parameters. In our model the SM quarks lighter than the top quark, get their masses from a low scale Universal seesaw mechanism, the SM charged lepton masses are produced by a Froggatt-Nielsen mechanism and the small light active neutrino masses are generated from an inverse seesaw mechanism. The model is consistent with the low energy SM fermion flavor data and successfully accommodates the current Higgs diphoton decay rate and predicts charged lepton flavor violating decays within the reach of the forthcoming experiments.

Runaway electron beam stability and decay in COMPASS

This paper presents two scenarios used for generation of a runaway electron (RE) beam in the COMPASS tokamak with a focus on the decay phase and control of the beam. The first scenario consists of massive gas injection of argon into the current ramp-up phase, leading to a disruption accompanied by runaway plateau generation. In the second scenario, injection of a smaller amount of gas is used in order to isolate the RE beam from high-temperature plasma. The performances of current control and radial and vertical position feedback control in the second scenario were experimentally studied and analysed. The role of RE energy in the radial position stability of the RE beam seems to be crucial. A comparison of the decay phase of the RE beam in various amounts of Ar or Ne was studied using absolute extreme ultraviolet (AXUV) tomography and hard x-ray (HXR) intensity measurement. Argon clearly leads to higher HXR fluxes for the same current decay rate than neon, while radiated power based on AXUV measurements is larger for Ne in the same set of discharges.

Fast Binary Embeddings and Quantized Compressed Sensing with Structured Matrices

This paper deals with two related problems, namely distance‐preserving binary embeddings and quantization for compressed sensing. First, we propose fast methods to replace points from a subset Χ ⊂ ℝn, associated with the euclidean metric, with points in the cube {±1}m, and we associate the cube with a pseudometric that approximates euclidean distance among points in Χ. Our methods rely on quantizing fast Johnson‐Lindenstrauss embeddings based on bounded orthonormal systems and partial circulant ensembles, both of which admit fast transforms. Our quantization methods utilize noise shaping, and include sigma‐delta schemes and distributed noise‐shaping schemes. The resulting approximation errors decay polynomially and exponentially fast in m, depending on the embedding method. This dramatically outperforms the current decay rates associated with binary embeddings and Hamming distances. Additionally, it is the first such binary embedding result that applies to fast Johnson‐Lindenstrauss maps while preserving ℓ2 norms.Second, we again consider noise‐shaping schemes, albeit this time to quantize compressed sensing measurements arising from bounded orthonormal ensembles and partial circulant matrices. We show that these methods yield a reconstruction error that again decays with the number of measurements (and bits), when using convex optimization for reconstruction. Specifically, for sigma‐delta schemes, the error decays polynomially in the number of measurements, and it decays exponentially for distributed noise‐shaping schemes based on beta encoding. These results are near optimal and the first of their kind dealing with bounded orthonormal systems. © 2019 Wiley Periodicals, Inc.

Investigations of the Ohmic Decay and the Soft X-Ray Emission of the High-braking-index Pulsar PSR J1640−4631

The young pulsar PSR J1640−4631 is the first pulsar reported with a high braking index, n = 3.15 ± 0.03, and has attracted extensive attention. In this work, by inputting the equation of state, we obtain two typical and feasible ranges of the electrical conductivity in the crust of PSR J1640−4631. Then, by considering the effects of general relativity, we formulate the induction equation and use it to investigate the decay of crustal magnetic fields within two scenarios: pure Ohmic decay, and the combination of Ohmic decay and Hall drift. In the former scenario, we calculate the current magnetic field decay rates as dBp/dt ∼ (0.78–1.00) × 107 G yr−1 and dBt/dt ∼ (0.82–1.05) × 108 G yr−1 for the poloidal and toroidal parts, respectively, and estimate the current magnetic energy decay rate as LB ∼ (0.95–1.22) × 1032 erg s−1. In the latter scenario, the combination of Ohmic decay and Hall drift accelerates the decay of magnetic fields, and we calculate the current magnetic field decay rates as dBp/dt ∼ (1.26–1.47) × 107 G yr−1, and dBt/dt ∼ (1.32–1.54) × 108 G yr−1 for the poloidal and toroidal parts, respectively, and estimate the current magnetic energy decay rate as LB ∼ (1.86–2.18) × 1032 erg s−1. It is found that the recalculated value of the braking index n of the star is lower than its observed value, which implies that other factors influence the spin-down evolution. The current magnetic energy decay rates calculated in both scenarios are far less than the isotropic soft X-ray luminosity obtained from Chandra+NuStar telescopes. The observed soft X-ray flux in the (2–10) keV band is FX ∼ 1.8(4) × 10−13 erg cm−2 s−1, which corresponds to a high surface temperature, T ∼ 1.54(6) × 106 K. The observed X-ray flux of the star could be caused by the decay of a multipolar magnetic field near the pole, which is strong enough to activate the slot-gap mechanism. The high surface temperature of the star is attributed either to magnetic spot formation or thermoplastic wave heating due to the decay of the toroidal field near the pole. Our results could be useful in interpreting the high soft X-ray flux from high magnetic field pulsars.

Long-Term Diabetic Microenvironment Augments the Decay Rate of Capsaicin-Induced Currents in Mouse Dorsal Root Ganglion Neurons.

Individuals with end-stage diabetic peripheral neuropathy present with decreased pain sensation. Transient receptor potential vanilloid type 1 (TRPV1) is implicated in pain signaling and resides on sensory dorsal root ganglion (DRG) neurons. We investigated the expression and functional activity of TRPV1 in DRG neurons of the Ins2+/Akita mouse at 9 months of diabetes using immunohistochemistry, live single cell calcium imaging, and whole-cell patch-clamp electrophysiology. 2′,7′-Dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescence assay was used to determine the level of Reactive Oxygen Species (ROS) in DRGs. Although TRPV1 expressing neuron percentage was increased in Ins2+/Akita DRGs at 9 months of diabetes compared to control, capsaicin-induced Ca2+ influx was smaller in isolated Ins2+/Akita DRG neurons, indicating impaired TRPV1 function. Consistently, capsaicin-induced Ca2+ influx was decreased in control DRG neurons cultured in the presence of 25 mM glucose for seven days versus those cultured with 5.5 mM glucose. The high glucose environment increased cytoplasmic ROS accumulation in cultured DRG neurons. Patch-clamp recordings revealed that capsaicin-activated currents decayed faster in isolated Ins2+/Akita DRG neurons as compared to those in control neurons. We propose that in poorly controlled diabetes, the accelerated rate of capsaicin-sensitive TRPV1 current decay in DRG neurons decreases overall TRPV1 activity and contributes to peripheral neuropathy.

Runaway electron experiments at COMPASS in support of the EUROfusion ITER physics research

The role of the COMPASS tokamak in research of generation, confinement and losses of runaway electron (RE) population is presented. Recently, two major groups of experiments aimed at improved understanding and control of the REs have been pursued. First, the effects of the massive gas injection ( Ar/Ne particles) and impurity seeding ( particles) were studied systematically. The observed phenomena include generation of the post-disruption RE beam and current conversion from plasma to RE. Zero loop voltage control was implemented in order to study the decay in simplified conditions. A distinctive drop of background plasma temperature and electron density was observed following an additional deuterium injection into the RE beam. With the loop voltage control the parametric dependence of the current decay rate dI/dt can be studied systematically and possibly extrapolated to larger facilities. Second, recent results of experiments focused on the role of the magnetic field in physics of RE were analysed. In this contribution, special attention is given to the observed effects of the resonant magnetic perturbation on the RE population. The benefits of the RE experiments on COMPASS was reinforced by diagnostic enhancements (fast cameras, Cherenkov detector, vertical ECE etc) and modelling efforts (in particular, coupling of the METIS and LUKE codes).

Non-destructive evaluation of ferromagnetic material thickness using Pulsed Eddy Current sensor detector coil voltage decay rate

A ferromagnetic material thickness quantification method based on the decay rate of the Pulsed Eddy Current sensor detector coil voltage is proposed. An expression for the decay rate is derived and the relationship between the decay rate and material thickness is established. Pipe wall thickness estimation is done with a developed circular sensor incorporating the proposed method, and results are evaluated through destructive testing. The decay rate feature has a unique attribute of being lowly dependent on properties such as sensor shape and size, and lift-off, enabling the method to be usable with any detector coil-based sensor. A case study on using the proposed method with a commercial sensor is also presented to demonstrate its versatility.

Effect of partially ionized impurities and radiation on the effective critical electric field for runaway generation

We derive a formula for the effective critical electric field for runaway generation and decay that accounts for the presence of partially ionized impurities in combination with synchrotron and bremsstrahlung radiation losses. We show that the effective critical field is drastically larger than the classical Connor–Hastie field, and even exceeds the value obtained by replacing the free electron density by the total electron density (including both free and bound electrons). Using a kinetic equation solver with an inductive electric field, we show that the runaway current decay after an impurity injection is expected to be linear in time and proportional to the effective critical electric field in highly inductive tokamak devices. This is relevant for the efficacy of mitigation strategies for runaway electrons since it reduces the required amount of injected impurities to achieve a certain current decay rate.

Measurement of Persistent Current in a Gd123 Coil With a Superconducting Joint Fabricated by the CJMB Method

Recently, we have proposed the concept of a crystalline joint by melted bulk (CJMB) for making a superconducting connection between GdBa2Cu3O7− δ (Gd123)-coated conductors (wire) using a wire-bulk-wire structure. In a model experiment, a joint between a Gd123-coated conductor and large piece of Y123 bulk (wire-bulk) as one-half of a joint was demonstrated, resulting in a superconducting joint with a critical current of 10 A at 77 K, and a high tensile strength greater than 100 MPa. In this study, a joint between coated conductors in a wire-bulk-wire structure was constructed using a Yb123 sheet fabricated from bulk material. As a result of using the CJMB method, we successfully fabricated a superconducting joint over the short time of less than 1 day (including joint formation and oxygen annealing). A persistent current coil having a superconducting joint was fabricated using the CJMB method. Its resistance was estimated from the current decay rate of the coil, to have a low value not exceeding 10−10 Ω after one day following the external power cutoff.

Suppressing self-discharge of supercapacitors via electrorheological effect of liquid crystals

For electric double layer capacitors (EDLCs, or supercapacitors), self-discharge has been an inevitable issue that causes decay of cell voltage and loss of stored energy, but this problem has long been ignored in the studying of supercapacitors. Due to self-discharge, applications of supercapacitors for long-term energy storage or collecting environmental energy harvested by small power devices have been severely limited. There are three main self-discharge processes for EDLCs, including i) charge diffusion and redistribution, ii) faradaic reactions, and iii) ohmic leakage. In this work, we introduced a nematic liquid crystal 4-n-pentyl-4′-cyanobiphenyl (5CB) as an additive to the electrolyte to suppress the self-discharge of EDLCs. When the EDLCs are charged, the electric field in the double layers near the electrode surface induces alignment of 5CB molecules, causing much enhanced fluid viscosity via the so-called electrorheological (ER) effect. As a result, the diffusion of ions and redox species in the electrolyte can be impeded and the self-discharge rate can be reduced. Here, we have demonstrated that by adding 2% of 5CB in TEMABF4/acetonitrile electrolyte, the decay rate of open circuit potential and leakage current can be reduced by more than 80%. Simulation results confirmed the reduced contribution of both diffusion of ions and faradaic reactions to the overall self-discharge. Furthermore, when 5CB EDLCs were employed for storing energy harvested by a triboelectric nanogenerator (TENG) that has a characteristic of pulsed output current, much enhanced charging efficiency was attained compared to EDLCs without 5CB. Our study pointing to a feasible way for truly pushing supercapacitor for practical applications.

Effects of glutamate and ivermectin on single glutamate-gated chloride channels of the parasitic nematode H. contortus.

Ivermectin (IVM) is a widely-used anthelmintic that works by binding to and activating glutamate-gated chloride channel receptors (GluClRs) in nematodes. The resulting chloride flux inhibits the pharyngeal muscle cells and motor neurons of nematodes, causing death by paralysis or starvation. IVM resistance is an emerging problem in many pest species, necessitating the development of novel drugs. However, drug optimisation requires a quantitative understanding of GluClR activation and modulation mechanisms. Here we investigated the biophysical properties of homomeric α (avr-14b) GluClRs from the parasitic nematode, H. contortus, in the presence of glutamate and IVM. The receptor proved to be highly responsive to low nanomolar concentrations of both compounds. Analysis of single receptor activations demonstrated that the GluClR oscillates between multiple functional states upon the binding of either ligand. The G36’A mutation in the third transmembrane domain, which was previously thought to hinder access of IVM to its binding site, was found to decrease the duration of active periods and increase receptor desensitisation. On an ensemble macropatch level the mutation gave rise to enhanced current decay and desensitisation rates. Because these responses were common to both glutamate and IVM, and were observed under conditions where agonist binding sites were likely saturated, we infer that G36’A affects the intrinsic properties of the receptor with no specific effect on IVM binding mechanisms. These unexpected results provide new insights into the activation and modulatory mechanisms of the H. contortus GluClRs and provide a mechanistic framework upon which the actions of drugs can be reliably interpreted.

The Impact of Tunnel FET on Heavy Ion Induced Transient Effect

The heavy ion induced response in Tunnel FET (TFET) is discussed by comparing to that in conventional MOSFET using device simulation. It was confirmed that both shorter transient current pulse and smaller collected charge were observed in TFET due to suppression of the parasitic bipolar effects. Introduction One of the detrimental problems with CMOS devices in radiation environments, such as space and around the nuclear reactors, is single event phenomena (SEP). When a high-energy particle irradiates to the device, electron-hole pairs are generated along the ion-track by ionization effect, and they can create a sufficient transient current to cause an incorrect device response (single event transient). Silicon-on-insulator (SOI) technology had been developed to reduce SEP, because the sensitive region was limited to the individual transistors isolated from the substrate. However, the reliability issue is more sensitive on a higher performance CMOS device with the small device size, thin active region and lower applying voltage1). In case of conventional n-type SOI-MOSFET, the generated electrons in channel region are drifted to drain region by applying drain bias. However, the generated holes remain in the channel region due to the source/drain-channel barrier, and they degrade the source-channel potential barrier. Therefore the electrons in source region are injected to channel, and that creates a large current between source and drain. These phenomena are known as parasitic bipolar effects2). The effects are more enhanced in smaller size devices. In this study, we focused TFET as a radiation hardened device. The TFET has been developed to improve the sub-threshold slope, and is consisted by p-i-n type, as source-channel-drain region, with applying reverse bias. So it is expected that the radiation induced electrons and holes in channel region are drifted to drain and source, respectively, and that the parasitic bipolar effects can be reduced by TFET. We evaluated the heavy-ion induced transient current and collected charge in conventional FET and TFET, and also discussed the single event transient on TFET CMOS devices. Simulation Model Figure (a) shows the cross section of the each SOI device, conventional MOSFET and TFET. We calculated heavy-ion induced transient current in these devices using a 2D device simulator. We set the heavy-ion with the LET of 10 MeVcm2/mg strikes to the center of the channel region in each OFF-state (V G = 0 V, V D = 1.5 V) device with normal incidence. In this case, the amount of radiation induced generation charge is 52 fC in the active layer (SOI region). Result Figure (b) shows the simulated results of transient current and collected charge, the time integral of the current, of each device. On the results of conventional MOSFET, the decay rate of transient current is much slower than the TEFT, and it is confirmed that the amount of collecting charge is saturated with about 500 fC, about 10 times as much as generated charges. It is considered that the phenomena are caused by the parasitic bipolar effect. On the other hand, in TFET device, the transient current reduces steeply and the collected charge is saturated with the same value of generated one. From these results, it was confirmed that the radiation induced collected charge can be reduced significantly using TFET. We also evaluated the change of band diagram in each device with time after irradiation. In the results of conventional MOSFET, the source-channel potential barrier is changed to almost zero by irradiation due to the holes stored in the channel region. In the case of TFET, it is found that the band diagram in not changed by irradiation. That indicates the generated electrons and holes can escape rapidly from the channel region due to the asymmetric source/drain doping structure in TFET. From these results, we confirmed that the parasitic bipolar effects could be eliminated using TFET. Acknowledgement This work is supported by VLSI Design and Education Center (VDEC), the University of Tokyo in collaboration with Synopsys, Inc. Reference 1) P. E. Dodd, et al.,”SEU-Sensitive volumes in Bulk and SOI SRAMs From First-Principles Calculations and Experiments” IEEE Trans. Nucl. Sci., Vol. NS-48, pp. 1893-1903. (2001) 2) V. Ferlet-Cavrois, et al., “Statistical Analysis of the Charge Collected in SOI and Bulk Devices Under Heavy lon and Proton Irradiation—Implications for Digital SETs” IEEE Trans. Nucl. Sci. Vol. 53, No. 6, pp. 3242-3252. (2006) 3) D. Kobayashi, et al., “Analytical Expression for Temporal Width Characterization of Radiation-Induced Pulse Noises in SOI CMOS Logic Gates” in proceedings of IEEE CFP09RPS-CDR 47th Annual International Reliability Physics Symposium, Montreal (2009) Figure 1

γ1-Containing GABA-A Receptors Cluster at Synapses Where they Mediate Slower Synaptic Currents than γ2-Containing GABA-A Receptors.

GABA-A receptors (GABAARs) are pentameric ligand-gated ion channels that are assembled mainly from α (α1–6), β (β1–3) and γ (γ1–3) subunits. Although GABAARs containing γ2L subunits mediate most of the inhibitory neurotransmission in the brain, significant expression of γ1 subunits is seen in the amygdala, pallidum and substantia nigra. However, the location and function of γ1-containing GABAARs in these regions remains unclear. In “artificial” synapses, where the subunit composition of postsynaptic receptors is specifically controlled, γ1 incorporation slows the synaptic current decay rate without affecting channel deactivation, suggesting that γ1-containing receptors are not clustered and therefore activated by diffuse neurotransmitter. However, we show that γ1-containing receptors are localized at neuronal synapses and form clusters in both synaptic and extrasynaptic regions. In addition, they exhibit rapid membrane diffusion and a higher frequency of exchange between synaptic and perisynaptic populations compared to γ2L-containing GABAARs. A point mutation in the large intracellular domain and a pharmacological analysis reveal that when a single non-conserved γ2L residue is mutated to its γ1 counterpart (T349L), the synaptic current decay is slowed from γ2L- to γ1-like without changing the clustering or diffusion properties of the receptors. In addition, previous fast perfusion and single channel kinetic experiments revealed no difference in the intrinsic closing rates of γ2L- and γ1-containing receptors when expressed in HEK293 cells. These observations together with Monte Carlo simulations of synaptic function confirm that decreased clustering does not control γ1-containing GABAAR kinetics. Rather, they suggest that γ1- and γ2L-containing receptors exhibit differential synaptic current decay rates due to differential gating dynamics when localized at the synapse.

Slow Current Discharges and Quenching of the MSU Superconducting Cyclotron Gas-Stopper Magnet

The Michigan State University cyclotron gas-stopper magnet generates a strong focusing cyclotron magnetic field that permits an ion beam of up to 100 MeV/u to enter the magnet and have most of its energy reduced by low-pressure helium gas. The magnet has two superconducting coil cryostats mounted within warm iron poles and a warm split iron return yoke. The coils are connected in series using room temperature cables. The peak magnet stored energy is 3.5 MJ. The magnet has been tested to its full operating current of 180 A. During tests, the magnet discharged inadvertently three times. Two low-current discharges caused the magnet current to decay through the power supply system. A discharge at 180 A quenched the magnet, because the quench protection system caused the magnet to discharge across a 1.25-Ω resistor. This fired the cold quench protection diodes within the cryostat, quenching both coils. The magnetic field in the gap was measured as the magnet discharged. For the two low-current discharges, the magnetic field followed the current in the external magnet circuit. During a quench, the magnetic field decay rate was much slower than the external circuit current decay rate.

RESEARCH OF SUCCESSIVE EXCITATION ELECTRIC MOTOR DYNAMIC MODES WITH PULSED SCHEMES OF THE ELECTRIC DRIVE REGULATION

Purpose: The purpose of the work is to research the dynamics of DC motor of series excitation with pulse speed control and determine the possibility of the drive circuit simplification. Research methods: With the help of simulation and analytical methods of calculation techniques developed a simulation model, identified the advantages of using a modernized impulse control scheme. The obtained results: The modernized scheme of series excitation DC current motor pulse control is designed. For the proposed and existing pulse regulation schemes the models are developed; they help to investigate the electromechanical processes of electric drive in these schemes and to perform the comparative analysis. The results of the modernized DC motor speed impulse control scheme investigation in the acceleration mode, overrun and electro-dynamic braking are given. Scientific novelty: Developed advanced pulse regulating sequential excitation DC motor scheme. For existing and proposed schemes impulse regulation developed models that allow study of electromechanical processes in electric drive for existing and proposed impulse control schemes. The practical significance: It is shown that the addition of a shunt field winding diode to pulsed regulator scheme reducing the rate of current decay in the winding. It is determined that the proposed upgrade allows to use electro-dynamic braking mode at the motor self-excitation. The proposed scheme design avoids the use of additional independent power sources and simplify the technical implementation and reduce costs.

Angular dependence of direct current decay in a closed YBCO double-pancake coil under external AC magnetic field and reduction by magnetic shielding

High Tc superconducting (HTS) coils are ideal candidates in the use of high field magnets. HTS coils carrying a direct current, however, suffer a non-negligible loss when they are exposed to an external AC magnetic field. Although this phenomenon is well known, no study concerning AC magnetic field angular dependence of direct current decay has ever been shown. In this work, we experimentally investigate the direct current decay characteristics in a closed double pancake coil made of a YBCO coated conductor under external AC field. AC field of different angles with respect to the coil plane is applied. Results show that the current decay rate presents a strong angular dependence. The fastest decay occurs when the field is parallel to the coil plane, in which case the surface of the tape in the outermost layer experiences most flux variation. To reduce the decay rate, we propose wrapping superconducting tapes around the outermost layer of the coil to shield external AC field. This method significantly reduces direct current decay rate under parallel field, without affecting the perpendicular self-field of the coil.

The modelling of an SF6 arc in a supersonic nozzle: II. Current zero behaviour of the nozzle arc

The present work (part II) forms the second part of an investigation into the behaviour of SF6 nozzle arc. It is concerned with the aerodynamic and electrical behaviour of a transient nozzle arc under a current ramp specified by a rate of current decay (di/dt) before current zero and a voltage ramp (dV/dt) after current zero. The five flow models used in part I [] for cold gas flow and DC nozzle arcs have been applied to study the transient arc at three stagnation pressures (P0) and two values of di/dt for the current ramp, representing a wide range of arcing conditions. An analysis of the physical mechanisms encompassed in each flow model is given with an emphasis on the adequacy of a particular model in describing the rapidly varying arc around current zero. The critical rate of rise of recovery voltage (RRRV) is found computationally and compared with test results of Benenson et al []. For transient nozzle arcs, the RRRV is proportional to the square of P0, rather than to the square root of P0 for DC nozzle arcs. The physical mechanisms responsible for the strong dependence of RRRV on P0 have been investigated. The relative merits of the flow models employed are discussed.

Pulsed positive streamer discharges in air at high temperatures

Atmospheric-pressure air pulsed positive streamer discharges are generated in a 13 mm point-plane gap in the temperature range of 293 K–1136 K, and the effect of temperature on the streamer discharges is studied. When the temperature is increased, the product of applied voltage and temperature VT proportional to the reduced electric field can be used as a primary parameter that determines some discharge parameters regardless of temperature. For a given VT, the transferred charge per pulse, streamer diameter, product of discharge energy and temperature, and length of secondary streamer are almost constant regardless of T, whereas the streamer velocity decreases with increasing T and the decay rate of the discharge current is proportional to 1/T. The N2(C) emission intensity is approximately determined by the discharge energy independent of T. These results are useful to predict the streamer discharge and its reactive species production when the ambient temperature is increased.

Making Better Use of Monitoring Data

This paper addresses the knowledge gap that exists in relation to understanding and quantifying the sensitivity of organic-rich archaeological deposits with respect to changes in the soil environment. Based on two case studies we demonstrate that it is possible to quantify the current decay rate in unsaturated archaeological deposits by combining decay rates measured in the laboratory with on-site monitoring data in a simple decay model. The decay of organic archaeological deposits is highly sensitive to variations in soil temperatures and soil water content. Measurements of soil water content cannot always stand alone as a representative measurement of oxygen availability; which suggests that in situ measurements of oxygen content or redox potential are needed in order to understand the preservation conditions at a site. The results of this study emphasize the advantage of combining monitoring data with laboratory studies, in order to document in more detail where and when degradation takes place.