Type Of Discharge Research Articles

A Lightning Classification Method Based on Convolutional Encoding Features

At present, for business lightning positioning systems, the classification of lightning discharge types is mostly based on lightning pulse signal features, and there is still a lot of room for improvement. We propose a lightning discharge classification method based on convolutional encoding features. This method utilizes convolutional neural networks to extract encoding features, and uses random forests to classify the extracted encoding features, achieving high accuracy discrimination for various lightning discharge events. Compared with traditional multi-parameter-based methods, the new method proposed in this paper has the ability to identify multiple lightning discharge events and does not require precise detailed feature engineering to extract individual pulse parameters. The accuracy of this method for identifying lightning discharge types in intra-cloud flash (IC), cloud-to-ground flash (CG), and narrow bipolar events (NBEs) is 97%, which is higher than that of multi-parameter methods. Moreover, our method can complete the classification task of lightning signals at a faster speed. Under the same conditions, the new method only requires 28.2 µs to identify one pulse, while deep learning-based methods require 300 µs. This method has faster recognition speed and higher accuracy in identifying multiple discharge types, which can better meet the needs of real-time business positioning.

Asymmetric and symmetric dimethylarginine as markers of endothelial dysfunction in cerebrovascular disease: A prospective study

Background and aimAsymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) have been proposed as mediators of endothelial dysfunction. In this study, we aimed to investigate the diagnostic and prognostic role of ADMA and SDMA in acute cerebrovascular disease. Methods and resultsA prospective case-control study was performed, enrolling 48 patients affected by ischemic stroke with no cardioembolic origin, 20 patients affected by TIA, 40 subjects at high cardiovascular risk and 68 healthy subjects.ADMA levels were significantly lower in high-risk subjects (18.85 [11.78–22.83] μmol/L) than in patients with brain ischemic event, both transient (25.70 [13.15–40.20] μmol/L; p = 0.032) and permanent (24.50 [18.0–41.33] μmol/L; p = 0.001). SDMA levels were different not only between high-risk subjects and ischemic patients, but also between TIA and stroke patients, reaching higher levels in TIA group and lower levels in stroke group (1.15 [0.90–2.0] vs 0.68 [0.30–1.07] μmol/L; p < 0.001). SDMA was also correlated with short-term prognosis, with lower levels in case of adverse clinical course, evaluated by type of discharge (p = 0.009) and need of prolonged rehabilitation (p = 0.042). ConclusionsThe present study highlights the relationship between l-arginine, ADMA, SDMA and acute cerebrovascular events. Therefore, our results suggested a potential role of SDMA as a specific marker of transient ischemic damage and as a short-term positive prognostic marker.

Partial Discharge Detection Method of Electrical Equipment Based on UHF Method

Partial discharge is an early symptom of insulation defects. In the field application, the detection method can not accurately identify those noise signals mixed in the partial discharge signal, which limits the detection to a certain extent. Based on UHF method, a partial discharge detection method for electrical equipment is designed. When partial discharge occurs, the exchange between charges, the radiation of electromagnetic waves and the consumption of energy will occur at the discharge position, causing the change of electrode potential. For the phase distribution spectrum, the signal characteristics produced by partial discharge are extracted from three aspects: statistical information, time domain information and frequency domain information. During detection, UHF sensor is placed on the basin insulator, and then UHF signal is received. Insulation defects are identified according to various differential discharge patterns formed by the discharge characteristics of different defects. Test results show that the signal spectrum detected by UHF partial discharge roughly matches the typical discharge spectrum, and it is determined that there is partial discharge in this area. This method has high positioning accuracy and meets the detection requirements of electrical equipment.

Numerical study on dust particle charging and dynamics in continuous and pulsed radio frequency argon discharges

AbstractCharging and dynamics of a spherical dust grain injected into a continuous and pulsed radio frequency (RF) discharge have been studied using a one‐dimensional fluid model. First, the plasma characteristics of the two types of discharges are computed and compared. In the pulsed discharge, it is found that the central electron density exhibits a periodic variation while the averaged electron density is lower compared to that in the continuous discharge due to the decrease in the total ionization rate. Further, the dust charge is computed using the plasma characteristics. It is found that the dust charge negatively increases as the duty cycle ratio increases. Also, the charge in the pulsed discharge is lower in comparison to the continuous discharge due to the shorter duration of the pulsed RF discharge limiting the amount of energy transferred to electrons. On the other hand, the dust particle remains in the powered sheath region exhibiting a damped oscillation in the two discharges with higher oscillation frequency in the continuous discharge.

Modeling and experimental comparison of pulsed-DC driven low-pressure plasma discharge in a metal tube

High-voltage pulsed-DC can be used to deposit films on the inner surfaces of tubes and pipes. However, the characteristics of the plasma discharge in the tubes and mechanisms of film deposition are not well understood. In this study, a discharge is formed in a metal tube inserted with a coaxial anode by microsecond (μs) pulsed power to explore the influence of the pulse parameters on the plasma characteristics, including the temporal and spatial evolution near the tube walls experimentally and by simulation. The discharge waveform is monitored by a voltage-current probe to analyze the impact of the electrical characteristics on the plasma. The plasma properties are diagnosed by a Langmuir probe and numerically calculated by the fluid model. The source voltage and current jointly influence the plasma density and electron temperature, and secondary electron emission by energetic ion bombardment affects not only the distribution of electron density measured by the probe, but also the temporal distribution during the pulse-on and pulse-off time. The electron temperature varies conversely with the density from the plasma zone to the cathode suggesting the typical glow discharge in the pulsed-DC tube. Secondary electron emission is created at a higher discharge frequency, and a sustained plasma between pulse cycles appears to be produced at a higher frequency. The results impart information about the pulsed-DC driven plasma discharge at low pressure as well as the role energetic ions play on the cathode and elucidate the mechanisms of plasma deposition on the interior tube wall.

Should I stay or should I go: an assessment of criteria for safe day of surgery discharge of displaced supracondylar humerus fractures.

Immobilization type and in-hospital observation following surgical management of displaced supracondylar fractures are subject to surgeon preference and training. Our goal was to determine criteria for immediate discharge and optimal type of immobilization. Medical records of 661 patients with type III, IV or flexion-type displaced supracondylar humerus fractures treated at a level 1 pediatric trauma center from January 2013 to September 2019 were reviewed. Patients were separated into 'admission appropriate' (AA = 113) and 'discharge appropriate' (DA = 548) sub-cohorts. Neurovascular deficit at presentation (P < 0.001), post-operative physical exam deterioration (P < 0.001), age (P < 0.001) and post-operative immobilization modality (P = 0.02) were significantly different between AA and DA groups. When comparing patients who presented with neurologic deficit to those neurovascularly intact, there was a significant difference in whether circumferential immobilization was used post-operatively (P < 0.001), IV medication need (P < 0.001), discharge or admission (P < 0.001), neurologic decline (P < 0.001), return to ED (P = 0.008) and vascular compromise (P = 0.05). Twenty-four of the 56 (43%) patients who were AA and had no neurovascular finding on presentation had their immobilization adjusted (bivalved or loosened) to accommodate for swelling overnight. Only 1 was initially maintained in a splint or bivalved cast; the other 23 were initially maintained post-operatively in circumferential immobilization (P = 0.01). Our findings suggest that patients with intact neurovascular exams at presentation are candidates for early discharge, and splinting or bivalved casting may be preferable, especially in patients who are discharged.

Flexible atmospheric brush-like microplasma jet source with needle-shaped protrusion electrode for internal surface treatment

In this paper, a flexible plasma jet source with newly designed needle-shaped protrusion (NSP) electrode capable of producing flexible atmospheric brush-like microplasma jet (FBµPJ) was developed and its application for internal surface treatment was investigated. The generator could maintain flexibility while possessing a certain degree of rigidity. Simulation and experimental results indicate that FBµPJ with NSP electrode was more efficient in generating the brush-like microplasma jets compared to conventional wire electrodes. The electrical characteristics showed that the discharge of this novel plasma source was a typical dielectric barrier discharge, and diverse oxygen-containing reactive species favorable for material surface treatment were observed. The internal surface of the silicone tube would get rougher and grafted with polar oxygen-containing functional groups after plasma treatment, and the inner surface can be transformed from hydrophobic to hydrophilic. Finally, the interfacial adhesion of the silicone tubes can be effectively enhanced by FBµPJ.

Gas Insulated Switchgear Partial Discharge Type Identification Based on Frequency Division Features and Improved Long Short-Term Memory Neural Networks

In order to ensure the safe and stable operation of gas insulated switchgear (GIS), a new method for identifying the type of partial discharge in GIS is proposed. First, the GIS partial discharge experimental platform produced four partial discharge signals. Second, the energy moments are calculated at each frequency to produce the frequency division features after the four partial discharge signals have been decomposed using variational modal decomposition (VMD). Finally, the type of GIS partial discharge is determined using the LSTM model enhanced by the quantum cuckoo search (QCS) algorithm. The experimental results show that the proposed method can successfully identify four types of partial discharge in GIS with an accuracy of 99%.

Edukasi Kesehatan Tentang Fluor Albus (Keputihan) Pada Ibu Hamil Dengan Service Excellent Education Di PMB Shinta Medan Polonia Tahun 2024

Fluorus albus (vaginal discharge) is white fluid that comes out of the sexual canal in excess. Fluorus albus is a vaginal fluid, not blood. During pregnancy, vaginal discharge increases in quantity. According to the World Health Organization (WHO), recommendations in America that reproductive health problems include 31.6% of pregnant women experiencing vaginal discharge (fluor albus) caused by the fungus Candida albican. In Indonesia, the problem of vaginal discharge is increasing, with more than 75% of women experiencing vaginal discharge due to the humid temperature in Indonesia, making them easily infected. candida albicans fungus, parasites such as pinworms or germs (trichomonas vaginalis) (WHO, 2019). According to data from the 2019 North Sumatra Province Health Profile, there were 648,829 pregnant women in 2019, 1,566 cases of pregnant women experiencing vaginal discharge, in the city of Medan in 2019 there were 855,281 people and 45% had experienced vaginal discharge (North Sumatra Health Profile, 2020) . Method: This activity begins with the preparation, implementation and evaluation stages. Results: 15 participants in this activity were pregnant women who visited PMB Shinta in Medan Polonia, Medan City. In its implementation, it was explained that the genital organ problem that pregnant women often experience, especially in the third trimester, is fluoride albus (vaginal discharge). The types of vaginal discharge also need to be understood as well as the treatment and therapy that needs to be given to pregnant women in preventing and treating cases of Fluor Albus. Conclusion: The results obtained from this community service activity are an increase in knowledge about preventing vaginal discharge and the treatment that will be carried out if complications occur. Pregnant women who experience vaginal discharge will pose a risk to the health and growth and development of their fetus later. The risk of vaginal discharge before and after was an increase of 15% for the good level of knowledge, and 27% for the sufficient level, and at the level of poor knowledge it decreased by 40%. With this change in the level of knowledge and strengthening understanding of Fluor Albus, it is hoped that pregnant women will be more aware of the conditions of their pregnancy, especially in maintaining personal hygiene which will result in disruption of fetal growth and development. Conclusion: The results obtained from this community service activity are an increase in knowledge about preventing vaginal discharge and the treatment that will be carried out if complications occur. Pregnant women who experience vaginal discharge will pose a risk to the health and growth and development of their fetus later. The risk of vaginal discharge before and after was 15% increased for the good level of knowledge, and 27% for the sufficient level, and for the poor knowledge level it decreased by 40%.

Research on a Partial Discharge Expert System for the Diagnosis of Damaged Transformation Equipment

Partial discharge (PD) characteristics are very important for the diagnosis of damaged transformation equipment. If the power transmission and transformation equipment fails, it will cause large economic losses, and thus prevention is better than treatment. One of the effective methods for high-voltage insulation degradation detection is to observe the phenomenon of partial discharge of equipment, which is the earliest characteristic. Prevention can be carried out in advance, and trend observation is better than periodic inspection. Long-term observation can effectively reduce the probability of misjudgment. This project intends to develop a high-speed data-acquisition device to acquire the original discharge waveform data of partial discharge for noise suppression. In order to improve the diagnostic efficiency and accuracy of the diagnostic system, it is necessary to suppress the noise of the measurement data, so as to carry out the fault identification of the discharge type. Through this method, the actual operating data of the system can be recorded as the original discharge waveform, in order to understand the original discharge waveform conditions of the power transmission and transformation equipment in multiple partial discharge measurements, and then after noise suppression, it can be regarded as a type of partial discharge identification.

Prediction of operating state of hydrocyclones using vibrometry and 1D convolutional neural networks

Due to high processing capacity requirements and constraints on industrial water utilization, operation of hydrocyclones at higher feed solid concentration is often unavoidable. Hydrocyclone operation at such higher feed solid concentrations is accompanied by the risk of onset of rope discharge, adversely affecting both the size separation and thickening performance of the hydrocyclone. Numerous condition monitoring efforts have been reported in the literature regarding the development of online techniques for detection of roping in hydrocyclones. However, detection of roping, post its commencement, only ever allows for corrective maintenance in the form of measures taken for shifting the discharge back to the desired spray profile. This study focuses on the characterization and online detection of a transition discharge state which precedes the onset of roping, thereby making the prevention of onset of roping, possible. The transition discharge state was delineated from the conventional spray and rope discharge types based upon the observed differences in the decay rates of underflow discharge spray angles with increasing feed solid concentrations. A binary classification model (spray – rope) and a ternary classification model (spray – transition – rope) were developed with a 1D Convolutional neural network architecture capable of taking 5 secs of tri-axial (3-channel) vibration signal data as input, and outputting the predicted discharge type labels with an accuracy of 97.31 % and 94.94 %, respectively.

Simulation of deuterium pellet ablation and deposition in the EAST tokamak with HPI2 code

Pellet injection is a primary method for fueling the plasma in magnetic confinement devices. For that goal the knowledges of pellet ablation and deposition profiles are critical. In the present study, the pellet fueling code HPI2 was used to predict the ablation and deposition profiles of deuterium pellets injected into a typical H-mode discharge on the EAST tokamak. Pellet ablation and deposition profiles were evaluated for various pellet injection locations, with the aim at optimizing the pellet injection to obtain a deep fueling depth. In this study, we investigate the effect of the injection angle on the deposition depth of the pellet at different velocities and sizes. The ablation and deposition of the injected pellet are mainly studied at each injection position for three different injection angles: 0°, 45°, and 60°. The pellet injection on the high field side (HFS) can achieve a more ideal deposition depth than on the low field side (LFS). Among these angles, horizontal injection on the middle plane is relatively better on either the HFS or the LFS. When the injection location is 0.468 m below the middle plane on the HFS or 0.40 m above the middle plane of the LFS, it can achieve a similar deposition depth to the one of its corresponding side. When the pre-cooling effect is taken into account, the deposition depth is predicted to increase only slightly when the pellet is launched from the HFS. The findings of this study will serve as a reference for the update of pellet injection systems for the EAST tokamak.

Plasma synthetic jet actuator array driven by a programmable triggered Marx high-voltage generator

A plasma synthetic jet (PSJ) actuator array driven by a self-triggered Marx high-voltage generator can simultaneously actuate multichannel PSJ actuators to form jet arrays; however, the discharge frequency cannot be controlled by programmable electrical signals. To address this, programmable high-voltage pulses are used to trigger a Marx high-voltage generator and regulate the discharge frequency of the PSJ actuator array. The electrode gap range for achieving a programmable triggered discharge is determined, and typical discharge images and basic discharge characteristics are obtained. The effects of trigger frequency and voltage amplitude on the discharge frequency are studied. The high-speed Schlieren technique is used to obtain flow-field characteristics of five-channel PSJ actuators under a programmable triggered state. The programmable triggered Marx high-voltage generator can achieve programmable control of the discharge frequency with an approximate linear control range of 10–30 Hz and a nonlinear saturation range of 30–100 Hz. In the approximate linear control range, the discharge frequency increases almost linearly with trigger frequency under different trigger voltage amplitudes. One of the channels of the five-channel synthetic jet actuators achieves the highest jet height and speed of 70 m/s, while those of the others are similar but slightly lower. There is no significant decrease in the jet height or speed of the five-channel PSJ actuators with the increase in the trigger frequency, which is beneficial for flow-control applications.

In situ dual-interface layer enabling lower resistance of Ta-doped Li7La3Zr2O12-based thermal battery

Application of Ta-doped Li7La3Zr2O12 (LLZTO) to thermal battery could solve overflow safety hazards caused by molten salt electrolytes. However, the capacity of large current discharge is obstructed by the large interfacial resistance originating from poor solid–solid contact between LLZTO and cathode. In this work, an in-situ dual-interface layer with favorable conductivity and multi-ionic diffusion between LLZTO and cathode is constructed by introducing connection layer in a simple way. The Ni(BrxCl2-x) layer with favorable conductivity would be established at high temperature during discharge for the reaction between the connection layer and NiCl2 cathode; the ionic (Br-,Cl-,O2–) diffusion layer with significant diffused direction among the connection layer, LLZTO layer and cathode layer occurs simultaneously at high temperature during discharge. Besides, the left connection layer with low melting point could form wettable interface as well. Consequently, the internal resistance of the single cell modified by in-situ dual-interface layer is reduced from 3.72 Ω to 1.70 Ω, accompanying with larger discharge current density (from 25 to 100 mA cm−2) and higher specific energy (from 444 to 1050 Wh kg−1) at 500 °C. Comparing with the typical discharge current of LLZTO which is less than 1 mA cm−2, this report provides a new insight to improve the interfacial resistance for the solid–solid contact at ambient temperature and the application for LLZTO on high-temperature battery.

Veterans Treatment Courts: A Nationwide Review of Enacting and Eligibility State Statutes

ABSTRACT Veterans Treatment Court (VTC) is the fastest growing type of treatment court in the United States with over 600 VTCs in operation today. Despite this recent proliferation, minimal scholarship has been conducted investigating how the state-level statutory landscape influences VTCs. The current study begins to address this gap by comprehensively reviewing and analyzing state legislation that governs the enactment, operation, and eligibility requirements of VTCs nationwide. Our initial search reveals that 70% of states currently operating VTCs are statutorily authorized at the state-level, of which nearly two-thirds also enumerates operational and eligibility criteria, such as military status and branch, mental health diagnosis, the “nexus,” criminal history, military discharge status, offense severity and type, and more. Our analysis indicates considerable variation and nuance across states but coalesced into several unifying themes. The results provide insights on one of the many important powers involved in shaping the operational and eligibility elements of VTCs – state legislatures – and can serve as a catalyst for future research on the myriad factors involved in determining how we conceptualize VTCs are and who is included in them.

Partial Discharge Type Identification of SF6 Gas Insulation Based on Crossover Features and Transformer Models

Abstract In order to effectively identify the type of partial discharge of SF6 gas-insulated switchgear combinations and then to ensure the safe and stable operation of the equipment, a method for identifying the type of SF6 gas-insulated partial discharge based on crossover frequency features and the transformer model is proposed. First, four types of SF6 gas-insulated partial discharge signals are gathered. These are then broken down into their modal components using variational modal decomposition. The energy moments of each crossover signal are then calculated to find the crossover frequency characteristics. Finally, the Transformer model is used to identify the types of SF6 gas-insulated partial discharge signals. The experimental results show that the proposed method can effectively recognize different partial discharge types of SF6 gas insulation, and the recognition accuracy is as high as 99%, which verifies the validity and superiority of the proposed method of recognizing partial discharge types of SF6 gas insulation.

Validation study of obstetric hospitalization data held on the Brazilian National Health System Hospital Information System for maternal morbidity surveillance: Brazil, 2021-2022.

To validate the Brazilian National Health System Hospital Information System (SIH/SUS) for maternal morbidity surveillance. This was a cross-sectional study conducted in 2021/2022, taking as its reference a national study on maternal morbidity (MMG) conducted in 50 public and 28 private hospitals; we compared SIH/SUS and MMG data for hospitalization frequency, reason and type of discharge and calculated sensitivity, specificity, positive and negative likelihood ratios for seven diagnoses and four procedures. Hospitalizations identified on SIH/SUS (32,212) corresponded to 95.1% of hospitalizations assessed by MMG (33,867), with lower recording on SIH/SUS (85.5%) for private hospitals [10,036 (SIH/SUS)]; 11,742 (MMG)]; compared to MMG, SIH/SUS had a lower proportion of hospitalizations due to "complications during pregnancy" (9.7% versus 16.5%) as well as under-recording of all diagnoses and procedures assessed, except "ectopic pregnancy". Better recording of diagnoses and procedures on SIH/SUS is essential for its use in maternal morbidity surveillance.

Characterization of Psychiatric Inpatients: The Role of Gender Differences in Clinical and Pharmacological Patterns.

Severe mental disorders that require hospitalization are disabling conditions that contribute to the burden of mental diseases. They pose increased clinical challenges and highlight the need to thoroughly explore variables emerging from daily clinical practice. In this study, we assessed to what extent gender differences may characterize a large population of psychiatric inpatients. We conducted a cross-sectional study in 2 Italian teaching medical centers, which included 2358 patients who were consecutively admitted to the psychiatric emergency units. We explored and characterized gender differences for variables such as prevalence of psychiatric diagnosis, presence of suicidal ideation, suicide attempts, age at onset of psychiatric illness, presence of substance or alcohol abuse, length of stay, number of hospitalizations, presence of involuntary admission, type of discharge from the hospital, and pharmacological treatment at discharge. Female patients were primarily diagnosed with bipolar disorder or personality disorders. Female patients had a significantly higher prevalence of lifetime suicide attempts (23.1% vs. 16.5%, P<0.001) and a longer length of hospitalization (11.43±10.73d vs. 10.52±10.37d, t=-2.099, gl=2356, P=0.036) compared with male patients. Male patients had more involuntary admissions (25.1% vs. 19.7%, χ2=9.616, gl=1, P=0.002), more use of illicit substances (34.1% vs. 20.9%, χ2=51.084, gl=1, P<0.001), and higher rates of alcohol abuse (21.3% vs. 14.7%, χ2=17.182, gl=1, P<0.001) compared with female patients. Finally, antidepressants and lithium were prescribed more frequently to the female patients, whereas other mood stabilizers were more often prescribed to the male patients. Our real-world results highlighted gender differences among patients with severe mental disorders admitted to psychiatric units, and suggest further investigations that may help in understanding trajectories accompanying disabling clinical conditions.

Influence of electron temperature anisotropy on the &lt;i&gt;m&lt;/i&gt; = 1 helicon mode power deposition characteristic

As a core phenomenon in helicon discharge, the plasma temperature anisotropy may play a crucial role in helicon wave power deposition. Under radially inhomogeneous plasma circumstances, by employing the warm plasma dielectric tensor model and considering the finite Larmor radius (FLR) effect and plasma temperature anisotropy effect, under the typical helicon discharge parameter conditions, the helicon wave and Trivelpiece-Gould (TG) wave mode coupling characteristic and influence of electron temperature anisotropy on the helicon wave power deposition induced by collisional and Landau damping mechanism are theoretically investigated. Detailed analysis shows that for typical helicon plasma electron temperature &lt;i&gt;T&lt;/i&gt;&lt;sub&gt;e &lt;/sub&gt;= 3 eV and low magnetic field &lt;i&gt;B&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt; = 48 G, the electron FLR effect should be considered, while the ion FLR effect can be ignored due to its large inertia effect; compared with the &lt;inline-formula&gt;&lt;tex-math id="Z-20240326171950"&gt;\begin{document}$| n | &lt; 2 $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="7-20231759_Z-20240326171950.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="7-20231759_Z-20240326171950.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; cyclotron harmonics, the contribution of the &lt;inline-formula&gt;&lt;tex-math id="Z-20240326171926"&gt;\begin{document}$| n | &gt; 1 $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="7-20231759_Z-20240326171926.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="7-20231759_Z-20240326171926.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; harmonics in the calculation of plasma dielectric tensor elements can be ignored due to low magnetic field conditions. For the propagation constant, detailed investigation indicates that the phase constant has a maximum value at a certain radial position, near the same position mode coupling between helicon wave and TG wave happens. Full analysis shows that the power deposition of the &lt;i&gt;m&lt;/i&gt; = 1 helicon mode peaks at a certain radial position and increases gradually with the increase of the axial electron temperature. Besides, compared with the Landau damping, the collisional damping plays a dominant role in the power deposition under current parameter conditions; importantly, the electron temperature anisotropy exerts a significant influence on the power deposition characteristic, both the increase and decrease of electron temperature anisotropy factor (&lt;i&gt;χ&lt;/i&gt; = &lt;i&gt;T&lt;/i&gt;&lt;sub&gt;e&lt;i&gt;,&lt;/i&gt;⊥&lt;/sub&gt;/&lt;i&gt;T&lt;/i&gt;&lt;sub&gt;e,&lt;i&gt;z&lt;/i&gt;&lt;/sub&gt;) can lead the power deposition intensity to change drastically. All these conclusions are very important for us to understand the discharge mechanism of helicon plasma.

Improved electro-mechanical model and energy conversion efficiency analysis of pulsed plasma thrusters

The primary electro-mechanical model is developed for the acceleration kinetics of electromagnetic railguns. Pulsed plasma thrusters (PPTs), whose operation principle is similar to that of electromagnetic railguns, generate thrust via electromagnetic acceleration of plasma. Therefore, the electro-mechanical model serves as a valuable analytical tool to explore the mechanisms of energy conversion and thrust generation of PPTs. In fact, a PPT initiates discharge at its propellant surface and then ejects the discharged channel away to form accelerated plume. During the acceleration, the plasma channel assumes a curved shape, which is different from the flat sheet shape. The curved geometric shape of PPT discharge channel makes the flat current sheet model currently used in the electro-mechanical models inherently flawed. In this paper, a two-dimensional (2D) curved current sheet model is proposed to improve the PPT electro-mechanical model, by referring to the curved morphology of PPT discharge plasma channels. &lt;xref ref-type="fig" rid="Figure1"&gt;Figure 1&lt;/xref&gt; shows the schematic of a typical PPT discharge circuit and the curved PPT discharge plasma channel that is indicated as the pink curve &lt;inline-formula&gt;&lt;tex-math id="M1"&gt;\begin{document}$ \widehat{ab} $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; according to the curved thin current sheet model. Also in &lt;xref ref-type="fig" rid="Figure1"&gt;Fig. 1&lt;/xref&gt; a current element &lt;inline-formula&gt;&lt;tex-math id="M2"&gt;\begin{document}$ {\mathrm{d}}\boldsymbol{l} $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;of the discharge channel is taken arbitrarily to display its instant velocity &lt;inline-formula&gt;&lt;tex-math id="M3"&gt;\begin{document}$ \boldsymbol{v} $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; and the Ampere force element &lt;inline-formula&gt;&lt;tex-math id="M4"&gt;\begin{document}$ {\mathrm{d}}\boldsymbol{F} $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; exerted by the magnetic field induced by the PPT current circuit. The pink dashed curve &lt;inline-formula&gt;&lt;tex-math id="M5"&gt;\begin{document}$ \widehat{cd} $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; represents the position of the current sheet just after time d&lt;i&gt;t&lt;/i&gt; . Using the 2D curved current sheet model and according to the detail shown in &lt;xref ref-type="fig" rid="Figure1"&gt;Fig. 1&lt;/xref&gt;, the Ampere force on discharge plasma channels and corresponding kinetics can be derived to obtain final kinetic energy of discharge plasma channels. As a result, the relation between the kinetic energy and the inductance of PPT discharge circuit is obtained and expressed as &lt;inline-formula&gt;&lt;tex-math id="M6"&gt;\begin{document}$ {E}_{{\mathrm{k}}}=\displaystyle\int _{0}^{{t}_{{\mathrm{e}}{\mathrm{n}}{\mathrm{d}}}}{i\left(t\right)}^{2}\frac{{\mathrm{d}}{L}_{{\mathrm{e}}{\mathrm{q}}}\left(t\right)}{{\mathrm{d}}t}{\mathrm{d}}t $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;. To determine the inductance as a temporal function, an algorithm for the inductance is proposed in which time-segment fitting of PPT discharge waveforms is adopted. Moreover, based on the temporal function of the inductance, PPT discharge waveforms can be simulated by using the ODE45 solver of MATLAB with high fitting goodness. So far, a calculation scheme for the kinetic energy of PPT plumes and simulation code for PPT discharge waveforms have set up based on the improved electro-mechanical model. To verify the improved model and the corresponding calculation scheme, the PPT prototype is used to evaluate its energy conversion efficiency. The results show that the model enables elucidating the low PPT electro-mechanical efficiency, which is attributed to the partition limitation of PPT energy to electromagnetic acceleration process. Accordingly, a possible exploration routine for elevating PPT electro-mechanical efficiency is suggested.