Electron energy distribution functions in low-pressure inductively coupled bounded plasmas

The electron energy distribution function(EEDF) in a low-pressure inductively coupled plasma confined between two infinite plates separated by 10cm is investigated using a one-dimensional particle-in-cell simulation including Monte Carlo collisions. At low pressure, where the electron mean free path is of the order of or greater than the system length, the EEDF is close to Maxwellian, except for its tail, depleted at high energy. We give clear evidence that this depletion is mostly due to the high-energy electrons escaping to the walls. As a result of the EEDF nonlocality, the break energy, for which the depletion of the Maxwellian starts, is found to track the plasma potential. At a higher pressure, the electron mean free paths of the various elastic and inelastic collisions become shorter than the system length, resulting in a loss of nonlocality and the break energy of the distribution function moves to energies lower than the plasma potential

Analisis KAPASITAS TERMINAL PETIKEMAS PELABUHAN TENAU KUPANG

Pada saat ini, utilisasi lapangan penumpukan di Pelabuhan Tenau Kupang relatif tinggi, sementara arus pergerakan peti kemas terus meningkat dan disi lain luas lapangan penumpukan terbatas. Studi ini dimaksudkan untuk mengetahui utilisasi lapangan penumpukan Pelabuhan Tenau Kupang menggunakan metode YOR (Yard Occupancy Ratio) dan menentukan pergerakan arus peti kemas 10 tahun ke depan menggunakan metode regresi serta mengoptimalisasi utilisasi lapangan penumpukan peti kemas dengan sejumlah skenario. Hasil penelitian menujukkan bahwa nilai YOR lapangan penumpukan peti kemas Pelabuhan Tenau Kupang sebesar102,14%. Atau dengan kata lain, kinerja lapangan penumpukan sudah melebihi Standar Dirjen Perhubungan Laut sebesar 60%. Untuk mengoptimalkan utilisasi lapangan penumpukan, peneliti melakukan sejumlah skenario. Dan skenario terbaik untuk mengoptimalkan lapangan penumpukan adalah menurunkan lamanya pengendapan peti kemas di lapangan penumpukan menjadi 3 hari

Ion heating in the presheath

A one-dimensional model of a small plasma ion source (10cm long) is studied. A hybrid simulation where ions are treated as particles and electrons as a fluid obeying the Boltzmann relation is used to investigate ion heating in the plasma presheath. At low pressure (below a few mTorr), the ion velocity distribution is Maxwellian in the bulk and becomes a drifting Maxwellian distribution while transiting the presheath. The distribution remains essentially isotropic as the ions are accelerated through the presheath to satisfy the Bohm criterion. At intermediate pressures (around 10mTorr), ion-neutral collisions scatter a significant part of the ion kinetic energy from the parallel direction to the perpendicular direction, leading to a net heating of the ions. In addition, the ion velocity distribution becomes distinctly anisotropic. At higher pressure (above a few tens of mTorr), ion heating is still observed, but yields isotropic ion velocity distributions

Particle-in-cell simulation of an electron shock wave in a rapid rise time plasma immersion ion implantation process

A one-dimensional Monte Carlo collision–particle-in-cell plasma computer code was used to simulate plasma immersion ion implantation by applying a negative voltage pulse to the substrate while the reactor wall is grounded. The results presented here show the effect of short rise time pulses: for rise times shorter than the electron plasma period (typically 5ns∕kV), an electron shock wave is observed where a rapidly expanding sheath heats the electrons up to high energies. Many of these fast electrons are expelled from the plasma leading to a high plasma potential and thus to a high surface electric field on the earthed electrode which could give rise to non-negligible electron field emission

One-dimensional particle-in-cell simulation of a current-free double layer in an expanding plasma

A one-dimensional particle-in-cell code using Monte Carlo collision techniques (MCC/PIC) for both ions and electrons is used to simulate our earlier experimental results which showed that a current-free electric double layer (DL) can form in a plasma expanding along a diverging magnetic field. These results differ from previous experimental or simulation systems where the double layers are driven by a current or by imposed potential differences. Both experiment and simulation show accelerated ions with energies up to about 60 eV on the low potential side of the plasma. A new numerical method is added to the conventional PIC scheme to simulate inductive electron heating, as distinct from the more common capacitively driven simulations. A loss process is introduced along the axis of the simulation to mimic the density decrease along the axis of an expanding plasma in a diverging magnetic field. The results from the MCC/PIC presented here suggest that the expansion rate compared to the ionization frequency is a critical parameter for the existence of the DL. For the DL to be absolutely current free, the source wall has to be allowed to charge: having both ends of the simulation at the same potential always resulted in a current flow. Also, the effect of the neutral pressure and of the size of the diffusion chamber are investigated. Finally we show that this particular type of DL has electrons in Boltzmann equilibrium and that it creates a supersonic ion beam

The ion velocity distribution function in a current-free double layer

A portable, low-power, diode laser-based laser-induced fluorescence(LIF)diagnostic incorporating a heated iodine cell for absolute wavelength reference was installed on the Chi-Kung helicon source [K. K. Chi, T. E. Sheridan, and R. W. Boswell, Plasma Sources Sci. Technol.8, 421 (1999)] to measure the ion velocity distribution function of argon ions as they transited a current-free double layer (DL) created where the solenoidal magnetic field diverges at the junction of the plasma source and the diffusion chamber. Based on LIFmeasurements of the transiting ion beam energy, the strength of the potential drop across the DL increases with decreasing neutral pressure and increasing magnetic field strength in the source. The location of the double layer also moves further downstream of the helicon source with increasing pressure. LIFmeasurements of the ion beam energy were found to be in good agreement with measurements obtained with a retarding field energy analyzer and also with numerical predictions.This work was supported by NSF Grant PHY-0315356, and the NSF EAPSI program in cooperation with Australian Academy of Science. A.M.K. was also supported by the DOE Fusion Energy Science Fellowship program

Variants in MME are associated with autosomal-recessive distal hereditary motor neuropathy

© 2019 The Authors. Annals of Clinical and Translational Neurology published by Wiley Periodicals, Inc on behalf of American Neurological Association. Objective: To identify a new genetic cause in patients segregating distal hereditary motor neuropathy (dHMN) with an autosomal recessive pattern. Methods: Whole-exome sequencing was conducted in two siblings and was combined with segregation analysis. Additionally, 83 unrelated dHMN patients with unknown genetic cause were screened. RNA analysis was performed using blood lymphocytes and HEK293 cells transfected with mutant plasmids. Immunohistochemistry and Western blot analysis was applied to the nerve tissue. The enzymatic activities of mutant proteins were measured in the cultured cells to verify the pathogenicity of variants. Results: The clinical features of the patients showed late-onset phenotype of distal motor neuropathy without sensory involvement. We identified that compound heterozygous variants of c.1342C\u27T and c.2071_2072delGCinsTT in the membrane metalloendopeptidase (MME) gene co-segregated with the phenotype in a dHMN family. In an additional group of 83 patients with dHMN, compound heterozygous variants of c.1416+2T\u27C and c.2027C\u27T in MME were identified in one patient. The splice site variant c.1416+2T\u27C results in skipping of exon 13. The stop variant c.1342C\u27T induces mRNA degradation via nonsense-mediated mRNA decay. Transcript levels of MME in the lymphocytes showed no significant differences between the patients and controls. We also identified that MME variants were associated with mild decrease in protein expression in the sural nerve and significant impairments of enzymatic activity. Interpretation: Variants in the MME gene were associated with not only a Charcot-Marie-Tooth neuropathy phenotype but also with an autosomal-recessive dHMN phenotype. Loss of function may play a role in the pathogenesis of dHMN

Travellers' profile, travel patterns and vaccine practices—a 10-year prospective study in a Swiss Travel Clinic

The travel clinic in Lausanne serves a catchment area of 700 000 of inhabitants and provides pre- and post-travel consultations. This study describes the profile of attendees before departure, their travel patterns and the travel clinic practices in terms of vaccination over time.; We included all pre-travel first consultation data recorded between November 2002 and December 2012 by a custom-made program DIAMM/G. We analysed client profiles, travel characteristics and vaccinations prescribed over time.; Sixty-five thousand and forty-six client-trips were recorded. Fifty-one percent clients were female. Mean age was 32 years. In total, 0.1% were aged <1 year and 0.2% ≥80 years. Forty-six percent of travellers had pre-existing medical conditions. Forty-six percent were travelling to Africa, 35% to Asia, 20% to Latin America and 1% (each) to Oceania and Europe; 19% visited more than one country. India was the most common destination (9.6% of travellers) followed by Thailand (8.6%) and Kenya (6.4%). Seventy-three percent of travellers were planning to travel for ≤ 4 weeks. The main reasons for travel were tourism (75%) and visiting friends and relatives (18%). Sixteen percent were backpackers. Pre-travel advice were sought a median of 29 days before departure. Ninety-nine percent received vaccine(s). The most frequently administered vaccines were hepatitis A (53%), tetanus-diphtheria (46%), yellow fever (39%), poliomyelitis (38%) and typhoid fever (30%).; The profile of travel clinic attendees was younger than the general Swiss population. A significant proportion of travellers received vaccinations that are recommended in the routine national programme. These findings highlight the important role of travel clinics to (i) take care of an age group that has little contact with general practitioners and (ii) update vaccination status. The most commonly prescribed travel-related vaccines were for hepatitis A and yellow fever. The question remains to know whether clients do attend travel clinics because of compulsory vaccinations or because of real travel health concern or both

Towards testing of a second-generation bladed receiver

A bladed receiver design concept is presented which offers a >2% increase in overall receiver efficiency after considering spillage, reflection, emission and convection losses, based on an integrated optical-thermal model, for a design where the working fluid is conventional molten salt operating in the standard 290–565°C temperature range. A novel testing methodology is described, using air and water to test the receiver when molten salt facilities are not available. Technoeconomic analysis shows that the receiver could achieve a 4 AUD/MWhe saving in levelised cost of energy, but only if the bladed receiver design can be implemented at no additional cost.The authors gratefully acknowledge the support of the Australian Renewable Energy Agency, 2014/RND010