Dark Discharge Research Articles

Discharge characteristics of the planar microscale gap electrodes with various geometry structures in the atmosphere environment

The discharge of microscale gaps for MEMS systems is a serious issue. To reveal the dark discharge characteristics of the microscale gap, electrodes with various gap feature sizes were prepared, and the DC current–voltage characteristics for the electrodes were implemented in atmospheric air. The results showed minor differences in dark discharge current on a nanoampere scale among electrodes with varying gap sizes of micro-protrusions. The current formation mechanism was consistent with the electron avalanche theory. Morphological characterization identified the presence of non-ideal thin-layer trailings at the electrode edges. To evaluate the effect of trailings on the dark discharge characteristics of the microscale gap structures, the electrodes with varying trailing lengths were fabricated. It showed that the current increased exponentially in the presence of long thin-layer trailing. In this case, the breakdown is most pronounced with an effective gap distance of 30 μm and a trailing length of 14.34 μm for the electrodes. For this structure, the dark discharge current was 198 nA at 36 V bias voltage, while the discharge current increased to 50 µA when the bias was increased to 37 V, and stabilized at 100 µA when the bias voltage was higher than 39 V. The rapid increase in current caused by trailing originates from the field emission as judged by the Fowler-Nordheim theory. Simulation results showed that the field strength can reach up to 3.76 × 109 V/m at a thin layer trailing length of 3.5 μm and a bias voltage of 200 V, which matches the conditions for the field emission. By calculating the effective secondary electron emission coefficient, it was found that thin-layer trailing significantly intensifies the ion-enhanced effect, further lowering the threshold for field emission and resulting in a rapid increase in microscale gap current at lower voltages.

Ruddlesden-Popper 2D Perovskite-MoS2 Hybrid Heterojunction Photocathodes for Efficient and Scalable Photo-Rechargeable Li-Ion Batteries.

Photo-rechargeable batteries (PRBs) can provide a compact solution to power autonomous smart devices located at remote sites that cannot be connected with the grid. The study reports the Ruddlesden-Popper (RP) metal halide perovskite (MHP) and molybdenum disulfide (MoS2) hybrid heterojunction-based photocathodes for Li-ion photo-rechargeable battery (Li-PRB) applications. Hybrid Lithium-ion batteries (LIBs) have demonstrated an average discharge specific capacity of 144.46 and 129.17 mAhg-1 for 50 cycles when operating at 176 and 294 mAg-1, respectively compared to the pristine LIBs which have shown specific capacity of 37.48 and 25.60 mAhg-1 under similar conditions. Hybrid Li-PRB has achieved an average dark discharge specific capacities of 128.66 mAhg-1 (capacity retention: 96.56%) which enhanced to 180.67 mAhg-1 under illumination (capacity retention: 97.39%; photo-enhancement: 40.42%) at 64 mAg-1. Excellent performance of hybrid Li-PRB is attributed to the formation of type-II heterojunction that leads to improved crystallinity and film morphology. The PRB has demonstrated a high photo conversion and storage efficiency (PC-SE) of 0.52% under standard 1 Sun illumination, which outperforms other previously reported MHP based LIBs and PRBs. This work provides a novel approach of harnessing the potential of MHPs for PRBs and offers new avenues for MHP photocathodes for various applications beyond PRBs.

The interelectrode discharge characteristics of the electrospray-type thrusters

In order to study the interelectrode discharge characteristics of the electrospray-type thrusters, an electrospray model and a test system have been established. The experiments are carried out with a variable pressure discharge of 6 × 10−3 Pa to 8 × 104 Pa at a polar spacing of 1.5–3.0 mm. The physical explanations of breakdown voltage, threshold current, breakdown voltage waveform, and frequency variation with pressure are discussed. Various electrical field behaviors between electrodes at specific pressure and voltage ranges are analyzed. The results show that the breakdown voltage characteristic curve of the polar spacing presents a typical minimum characteristic, and the breakdown voltage of the electrospray model can be significantly improved by reducing the pressure below 10−1 Pa. The emission current of the vacuum working area is larger than that of the near-atmosphere working area, and the threshold current of the failure area is very low. The breakdown voltage waveform is periodic and changes abruptly at about 20 Pa. Before the mutation, the breakdown voltage frequency is inversely related to the pressure and the polar spacing. After the mutation, it is positively linearly related to the pressure and inversely related to the polar spacing. With the reduction in air pressure, different forms of discharge occur between the electrodes. Before the breakdown, corona discharge and dark discharge occur in turn. After the breakdown, spark discharge, arc discharge, glow discharge, and vacuum spark discharge all occur in turn.

Experimental study on positive corona discharge characteristics in plane-single/double earthed rods air gaps under negative DC voltage

In order to analyze the corona discharge characteristics at the grounding object tip under the thundercloud electric field environment, scaled simulation test has been conducted on corona discharge in the plane-single/double earthed rods air gap. Five gap configurations with three different grounding rods were built during experiments. Factors as rod tip curvature, voltage and gap configuration have been considered in detail. Corona voltage, corona current and the number of ultraviolet photons were all recorded. The grounding rod tip curvature radius can affect corona discharge processes at grounding rod tip. With increasing applied negative DC voltage, five typical corona processes of dark discharge, burst streamer corona, periodic streamer corona, glow corona and brush discharge occurred at conical and spherical grounding rod tip (r=0.75cm), but under d=5cm and d=10cm no glow corona and brush corona appeared at spherical grounding rod tip (r=1.25cm). It is much easier for grounding rod tip with smaller curvature to form glow corona phenomenon. The mean value Iav of periodic streamer corona current pulse amplitude decreases with grounding rod tip curvature radius, while the mean corona current pulse width and pulse interval increases. For grounding rod with conical tip, there is little difference of average current pulse amplitude between periodic streamer corona and brush corona; for grounding rod with spherical tip (r=0.75cm), the mean value Iav of brush corona pulse amplitude increases to 3595.8 μA which has increased by a factor of about 36. The photon number at conical grounding rod tip is larger than that at spherical grounding rod tip at low voltage but the relation reverses as the applied voltage exceeds a critical value. The shielding effect of two grounding rods in plane-double rods air gaps increased with spherical grounding rod curvature radius and decreases with the lateral gap distance between two grounding rods.

Formation of honeycomb-Kagome hexagonal superlattice pattern with dark discharges in dielectric barrier discharge

A honeycomb-Kagome hexagonal superlattice pattern with dark discharges is observed in a dielectric barrier discharge system for the first time. The spatiotemporal structure of the honeycomb-Kagome hexagonal superlattice pattern with dark discharges is investigated by an intensified charge-coupled device and the photomultipliers show that it is an interleaving of three different sub-lattices, which are bright-spot, invisible honeycomb lattice, and Kagome lattice with invisible frameworks and dim-spots, respectively. The invisible honeycomb lattices and Kagome lattices are actually composed of dark discharges. By using the optical emission spectra method, it is found that the plasma parameters of the three different sub-lattices are different. The influence of the dark discharges on pattern formation is discussed. The results may have significance for the investigation of the dark discharges and will accelerate the development of self-organized pattern dynamics.

Photovoltage memory effect in a portable Faradaic junction solar rechargeable device

Two-electrode solar rechargeable device is one of the promising technologies to address the problem of solar energy storage in large scale. However, the mechanism of dark output voltage remains unclear and the low volumetric energy density also limits its practical applications. Herein, we report that a Si/CoOx/KBi(aq)/MnOx Faradaic junction device exhibits a photovoltage memory effect, that is, the dark output voltage can precisely record the value of the photovoltage in the device. To investigate the mechanism of the effect, we develop an open circuit potential method to real-time monitor the photo charge and dark discharge processes in the Faradaic junction device. This effect leads to minimized interface energy loss in the Faradaic junction device, which achieves much higher performances than the devices without the effect. Moreover, we realize a portable device with a record value of the dark volumetric energy density (∼1.89 mJ cm−3) among all reported two-electrode solar rechargeable devices. These results offer guidance to improve the performance of a solar rechargeable device and design other photoelectric devices for new applications.

One-body style photo-supercapacitors based on Ni(OH)2/TiO2 heterojunction array: High specific capacitance and ultra-fast charge/discharge response

In this work, a type of “one-body” photo-supercapacitors (PSs) with high specific capacitance and ultrafast response of charge/discharge is constructed, in which TiO 2 plays a role of photoelectric conversion material and Ni(OH) 2 serves as the energy storage material. The results show that the discharge specific capacitance of 22.9 mF/cm 2 and the charge and discharge response time of 40 and 30 ms in this type of PSs is prior to that in previous works. The large discharge specific capacitance and ultrafast response mainly attribute to the direct storage and release of charges in loose Ni(OH) 2 structure. This study provides a simple fabrication process of PSs with high performance for the direct storage of solar energy and offers reference for the application of other materials in PSs. • The morphology of Ni(OH) 2 on TiO 2 nanorod arrays could be regulated precisely. • TiO 2 nanorod arrays loaded with flower-like Ni(OH) 2 showed p-n junction effect. • Photo charge and dark discharge can be performed by the same working electrode. • The PSs showed ultrafast response, high specific capacitance and stability.

COMPARATIVE CHARACTERISTICS (CASE - CONTROL) OF WOMEN WITH AND WITHOUT ENDOMETRIOID DISEASE

Endometrioid disease today is ranking one of the leading positions in the structure of gynaecological diseases. The prevalence of this endometrioid disease reaches 10% among the female population and up to 70% among women of child-bearing age. Ambiguity in terms of the aetiology, pathogenesis, and predictors of the disease impedes the accurate and quick diagnosis and proper management of this disease.
 The aim of this study is to analyze and to compare symptomatic and anamnestic data presented by women who have with endometrioid disease and have no it, and to identify and analyze predictors and consequences of endometrioid disease.
 The study examined 80 women of reproductive age. The main group involved 50 women with endometrioid disease; the control group included 30 women without signs of endometrioid disease. All participants underwent clinical examination and were interviewed about symptoms, family history, menstrual function, past gynaecological, reproductive, infectious (infectious diseases, transferred in childhood), somatic diseases. The information about the presence of psychological and physical overstrain in women of both groups was obtained (subjectively from the words of women) and then assessed.
 Contributory factors or predictors in the development and progression of endometrioid disease are as follows: an increased number of occupational hazards (22.6% versus 0%, respectively, p = 0.03) among working women with endometrioid disease; regular psychological overstrain, which can result from endometrioid disease on the one hand, and, contribute to its progression, on the other (70% versus 43.3%; p = 0.03); the presence of the 0 blood type (40% versus 16.7%; p = 0.029), the presence of chronic inflammation of the uterine appendages in the past (60% versus 36.6%; p = 0.04); human papilloma virus in past or present medical history (14% versus 0%; p = 0.04).
 The possible consequences of endometrioid disease include somatic pathology prevailing in 1.3 times. Special attention should be paid to the average number of gastro-intestinal diseases in the women of main and control groups: 1.34 ± 1.3 versus 0.77 ± 1.1, respectively; p = 0.04. The prevalence of diseases of urinary system is as follows: 0.66 ± 0.68 versus 0.33 ± 0.54, respectively; p = 0.04. The menstruations are described as irregular, heaving bleedings often with dark brown discharge before menstruation, pain during menstruation. The study revealed a large percentage of infertility in patients with endometrioid disease (60% versus 33.3%, respectively; p = 0.02), reduced reproductive potential in general (the average number of pregnancies per woman in the control group is 1.9 times higher).
 It should be noted that 14 (28%) women of the main group have relapse of endometrioid disease in the form of repeated cysts after conservative and / or surgical treatment. Thus, endometrioid disease was detected for the first time in 36 (72%) women of the main group.
 The information obtained in the study can be helpful for medical practitioners as it deepens knowledge about possible predictor factors, premorbid background and the consequences of endometrioid disease, and, thus, will serve in customized management of such patients.

A Capacitor‐type Faradaic Junction for Direct Solar Energy Conversion and Storage

AbstractTwo‐electrode solar rechargeable devices trigger intense attention due to their potential applications in solar energy conversion and storage. However, interface energy barriers lead to severe loss of output voltage and negligible dark discharge current. Therefore, external biases are required for dark discharge in these devices, limiting their practical applications. Herein, we report a new two‐electrode device of Si/WO3/H2SO4(aq)/C that can work without bias. The device has the highest dark output power among all of the two‐electrode solar rechargeable devices. The device based on a Si/WO3 junction indicates photoinduced adjustable interface barrier height during charge transfer, which can overcome the energy barrier and realize dark discharge without bias. Owing to the interface characteristics, the Si/WO3 is designated as a capacitor‐type Faradaic junction.

A Capacitor-type Faradaic Junction for Direct Solar Energy Conversion and Storage.

Two-electrode solar rechargeable devices trigger intense attention due to their potential applications in solar energy conversion and storage. However, interface energy barriers lead to severe loss of output voltage and negligible dark discharge current. Therefore, external biases are required for dark discharge in these devices, limiting their practical applications. Herein, we report a new two-electrode device of Si/WO3 /H2 SO4(aq) /C that can work without bias. The device has the highest dark output power among all of the two-electrode solar rechargeable devices. The device based on a Si/WO3 junction indicates photoinduced adjustable interface barrier height during charge transfer, which can overcome the energy barrier and realize dark discharge without bias. Owing to the interface characteristics, the Si/WO3 is designated as a capacitor-type Faradaic junction.

Photo electric properties during streamer-to-leader transition in a long positive sphere–plane gap

In this work, a combined photoelectric detecting system is established using devices such as a photomultiplier, an electric field sensor based on optoelectronic integration, and a high-speed camera. The system is used to measure the instantaneous optical power, spatial electric field strength, and optical image during discharge of a 3-m-long sphere–plane gap under standard switching surge voltage of positive polarity. The test results show that the initial streamer of the 3-m-long sphere–plane gap can be divided into strong and weak ionization according to the rate of rise of optical power and electric field strength. Within the dark discharge period in the sphere–plane air gap, the intensity of the spatial electric field slightly jumps when the streamer-to-leader transition is completed, with an increase of about 162.59 kV/m. It is proposed to take the time when the intensity of the spatial electric field jumps in the dark discharge period as the criterion for the streamer-to-leader transition. The measured duration ta of the streamer-to-leader transition is calculated according to instantaneous optical power and spatial electric field strength. Based on the thermodynamic equilibrium equation, a Gallimberti simulation model for this streamer-to-leader transition is established. The duration ts for completing the streamer-to-leader transition is obtained according to the quantity Q of injected electric charges. By comparing the measured duration ta with the calculated duration ts of the streamer-to-leader transition, the rationality of the criterion is verified. The research results provide a basis for establishing an improved model for the inception of a leader in a long air gap.

Investigation of the initial phases of nanosecond discharges in liquid water

In this work, we examine initial phases of micro-discharges produced in deionised water by high-voltage (HV) pulses of nanosecond duration. We apply opto-electrical diagnostics with extremely high temporal (down to 30 ps) as well as spatial (down to 1 μm) resolution. Frozen interferometric and shadowgraph images show three distinct events. The first, the subcritical (no-discharge) event, is characterised by periodic perturbations of the index of refraction which depart from the anode surface and are pulled away at the speed of sound as an expanding envelope defined by the shape of the anode tip. One-dimensional hydrodynamic modelling of the subcritical phase under conditions mimicking curvatures of real anode tips reveals basic characteristics of perturbations caused by dynamic balance between the hydrostatic and electrostrictive pressures consistent with experimental observations. The second, the dark or non-luminous discharge event, is characterised by the onset of a few isolated very tiny tree-like structures growing from the anode tip. Depending on the HV amplitude, the initial structures occur with a delay of ∼2–3 ns after onset of the HV pulse and subsequently expand with average velocity of ∼1 × 105–2 × 105 m s−1, creating very dense bush-like structures made of thin hair-like filaments in a few nanoseconds. The third, the luminous discharge event, follows (nearly simultaneously) the dark discharge event and unveils much simpler tree-like morphology determined by the extension of non-luminous bush-like structures. Characteristic dimensions of observed events range from about 1 μm (typical diameter of non-luminous filaments) to tens of micrometres (characteristic diameters of luminous filaments). Furthermore, we address a possible role of microbubbles developing in the anode region due to the periodic HV pulses and verify that the UV-vis-NIR spectrometric signatures of the luminous phase notably change when replacing non-degassed deionised water with degassed.

The Genome of Caenorhabditis bovis.

The free-living nematode Caenorhabditis elegans is akey laboratory model for metazoan biology. C.elegans has also become a model for parasitic nematodes despite being only distantly related to most parasitic species. All of the ∼65 Caenorhabditis species currently in culture are free-living, with most having been isolated from decaying plant or fungal matter. Caenorhabditis bovis is a particularly unusual species that has been isolated several times from the inflamed ears of Zebu cattle in Eastern Africa, where it is associated with thedisease bovine parasitic otitis. C.bovis is therefore of particular interest to researchers interested in the evolution of nematode parasitism. However, as C.bovis is not in laboratory culture, it remains little studied. Here, by sampling livestock markets and slaughterhouses in Western Kenya, we successfully reisolated C.bovis from the ear of adult female Zebu. We sequenced the genome of C.bovis using the Oxford Nanopore MinION platform in a nearby field laboratory and used the data to generate a chromosome-scaledraft genome sequence. We exploited this draft genome sequence to reconstruct the phylogenetic relationships of C.bovis to other Caenorhabditis species and reveal the changes in genome size and content that have occurred during its evolution. We also identified expansions in several gene families that have been implicated in parasitism in other nematode species. The high-quality draft genome and our analyses thereof represent a significant advancement in our understanding of this unusual Caenorhabditis species.

Channel-like 360° Isthmocele Treatment with a 16F Mini-Resectoscope: A Step-by-step Technique

To show the technique of hysteroscopic channel-like 360° repair of a cesarean scar defect performed with a Gubbini 16F miniresectoscope (GUBBINI system; Tontarra Medizintechnik, Tuttlingen, Germany). A step-by-step demonstration of the surgical technique using slides, pictures, and a video (an instructive video [Video 1]). A university hospital (Bologna University Hospital, Sant'Orsola-Malpighi Polyclinic, Bologna, Italy). A 35-year-old woman with a history of a previous cesarean section complaining of pelvic pain and postmenstrual spotting. With the vaginoscopic approach, the isthmocele was localized; a high-frequency 90° angled circular loop electrode and pure cutting current of 100 W were used to resect the fibrotic tissue of the proximal (step 1) and distal (step 2) part of the niche. We performed resection not only of the fibrotic tissue underneath the niche but also of the inflamed tissue placed around the niche and on the opposite site (the so-called channel-like 360° endocervical ablation). A high-frequency angled ball electrode was used to obtain focused coagulation of all residual inflamed tissue still present on the niche surface and on the cervical canal walls (step 3); the aim of this step is to facilitate the re-epithelialization of the cervical canal walls by the paraphysiological endocervical epithelium. The procedure was ended by controlling any bleeding of the endocervical vessels by reducing the inflow and pressure of the distending medium and by focused electrocauterization with a ball electrode (step 4). The operative time was 14 minutes. The small diameter of a 16F resectoscope and the use of a miniaturized loop without cervical dilation allow the operative procedures to be performed without cervical dilation and without anatomic distortion of the defect, reducing the risk of complications. The small diameter of the sheaths also makes the surgical gesture faster with an easier and faster approach to the niche compared with isthmocele hysteroscopic standard surgery. The presence of a uterine scar defect is usually asymptomatic or refers to postmenstrual spotting with dark red or brown discharge, dysmenorrhea, dyspareunia, chronic pelvic pain, infertility, or a dull sensation after menstruation. Several factors may play a role in isthmocele development such as a low uterine incision, a deficient suturing technique of the uterine incision, and patient-related factors that impair wound healing or increase inflammation or adhesion formation. Different techniques were used as reconstructive therapies of the cesarean scar defect including laparoscopic or robot-assisted laparoscopic excision, vaginal repair, or hysteroscopic treatment. All of these procedures remove or ablate the niche fibrotic tissue with the aim of relieving symptoms. Asymptomatic cases should not be treated. According to the most recent literature, hysteroscopic repair of a cesarean scar represents an effective and safe surgical option in cases of a symptomatic isthmocele. The persistence of symptoms has been reported in up to 18% of cases, so adequate counseling should be performed before the procedure.

Triangular lattice pattern with invisible Kagome lattice in dielectric barrier discharge system

We present the triangular lattice pattern with the invisible Kagome lattice in the dielectric barrier discharge system with two water electrodes for the first time. The spatio-temporal dynamics studied by an intensified charge-coupled device (ICCD) show that the complex pattern is composed of four different sublattices: Kagome lattice, halos, and big and small spots (B and S). The invisible Kagome lattice is similar to the dark discharge because of its spatio-temporal randomness. Based on the novel discharges (B and S) occurring at the falling edge of applied voltage, the dynamics of surface charges is investigated and demonstrated with a high speed video camera and photomultiplier tubes. Furthermore, the formation of restricted random structures is considered to be the effect of previous discharges which rearrange the surface charges.

Boerhaave syndrome in emergency abdominal surgery

Aim. To present a case of spontaneous rupture of esophagus taking into account its rarity, diversity of clinical manifestations, complexity of making a diagnosis and treatment of this disease.Methods. Over the past three years in Kazan City Clinical Hospital №7 three cases of the esophageal damage were registered. The age of the patients ranged from 48 to 67 years, including 2 females and 1 male with spontaneous rupture of esophagus.Results. A 48-year old patient was admitted to the hospital complaining of vomiting with blood followed by appearance of retrosternal pain which appeared immediately after the holiday and nutritional stress. Emergency fibrogastroduodenoscopy (FEGDS) was performed. Endoscopy revealed signs suggestive of diaphragmatic hernia, and 2 ruptures of esophageal mucous membrane up to 3 cm on the left wall of esophagus above the cardiac sphincter. The diagnosis of Mallory-Weiss syndrome complicated with bleeding was made. Surgery: laparotomy, abdominal revision. The abdominal cavity had dark hemorrhagic discharge, inflamed peritoneum and signs of diffuse peritonitis. Diaphragmatic crurotomy was performed. Revision of abdominal esophagus revealed two longitudinal ruptures of the left esophageal wall 1.5 and 3 cm long 8 cm up from the cardiac sphincter. The ruptures were sutured by discontinuous atraumatic encircling stitch. Lower mediastinum was drained with two double-lumen tubes, the gastric probe was installed through the nose. During the follow up CT scan and ultrasound of thoracic cavity were performed. Liquid nutrition through the probe lasted up to 20 days. The mediastinum was lavaged through double-lumen tube with an aqueous solution of chlorhexidine and chymotrypsin up to 32 days. The patient was discharged on day 34 in a satisfactory condition.Conclusion. One of the etiologic factors of spontaneous esophageal rupture may be diaphragmatic hernia of the esophagus with increased intraesophageal pressure; early surgical intervention, suturing of esophageal rupture, mediastinal drainage and lavage in the postoperative period are fundamental steps in the treatment of esophageal rupture.

A Case of Dystocia Induced by Misuse of Oxytocin in a Boerboel Bitch

A two year old boerboel bitch with dark greenish vaginal discharge and history of over 24 hours of difficult labor was presented to the Veterinary Teaching Hospital University of Ibadan for clinical examination and treatment. The owner had wrongfully given oxytocin after observation of signs of parturition. Following careful physical and clinical examinations of the bitch by Veterinary doctors, dystocia due to obstruction of maternal birth canal by a dead fetus was diagnosed. Treatment regimen was by digital manipulation which stimulated cervical dilatation and careful delivery of dead fetus via the vagina. Thereafter, oxytocin was administered to augment the bitch’s weak uterine contraction. Four weak puppies were delivered out of which three survived following adequate treatment.

Criticality of External Circuit in Simulating Atmospheric Pressure Direct Current Microglow Discharge

The effects of the external circuit on discharge conditions are not explicitly considered in most numerical simulations of nonthermal plasma discharges. The effects of including and excluding the external circuit on the simulation of atmospheric pressure reactive microglow discharges are addressed. 2-D simulations of direct-current (dc) atmospheric pressure H 2 /CH 4 microglow discharges were conducted using a hybrid model. The external circuit consisted of a ballast resistance (in series) and a parasitic capacitance (in parallel) connected to the discharge electrodes. Simulations were conducted over a broad discharge current range (by varying ballast resistance). The parasitic capacitance values were also varied to examine the effects on discharge behavior. Depending on the value of the ballast resistance, the discharge operated in the subnormal (large ballast resistance) and normal glow (small ballast resistance) regimes. When the external circuit is not considered, the discharge was found to operate in the Townsend like regime as a dark discharge. The simulations further indicated that for higher values of the parasitic capacitance, the discharge (even with a dc power supply) was self-oscillatory, indicating an unstable regime. The oscillations were found to arise as a result of comparable time scales between the ion transit time (τ ion ) within the interelectrode separation and the circuit response time (τ RC ). The predicted results were found to be in agreement with experimental observations.

Photoinduced and Dark Discharge of Overcoated High-Gamma Photoreceptors

A single-layer organic photoreceptor for electrophotography with relatively low concentrations of phthalocyanine pigments dispersed in a suitable insulating binder polymer, which exhibits the induction effect, is generally referred to as a high-gamma photoreceptor. Surface charges from corona ions can be injected into the photoconductive layer through chemicals adsorbed on the free surface generated by corona discharge. It has been confirmed experimentally and theoretically that an overcoat layer is effective in protecting the surface of the high-gamma photoreceptor from surface-charge injection. In this study, a high-gamma photoreceptor with X-type metal-free phthalocyanine pigment dispersed in polyester binder polymer is overcoated with isocyanate. The theoretical model, which takes into account the distributed structural-trap depth, demonstrates well the photoreceptor’s photoinduced-discharge and dark-discharge characteristics.

Photoinduced and Dark Discharge of Overcoated High Gamma Photoreceptors

Photoinduced and Dark Discharge of Overcoated High Gamma Photoreceptors