Large area multi-filamentary plasma source for large volume plasma device-upgrade.

This paper discusses the salient features and plasma performance of the newly installed Large Area Multi-Filamentary Plasma Source (LAMPS) in large volume plasma device-upgrade. The plasma source is designed to exhibit a plasma electron density of ∼1018 m-3, low electron temperature (∼eV), and a uniform plasma cross section of 2.54 m2. The directly heated LAMPS emits accelerated primary energetic electrons when it is biased with a negative discharge voltage with respect to the anode. The hairpin shaped tungsten (W) filaments, each of diameter 0.5 mm and length 180 mm, are heated to a temperature of 2700 K by feeding ∼19.5A to each filament. The LAMPS consists of 162 numbers of filaments, and it has been successfully operated with a total investment of 50 kW of electrical power. The LAMPS as a laboratory plasma source is characterized by large operational life, ease of handling, better compatibility to high pressure conditions, and advantages over other contemporary plasma sources, viz., oxide coated cathodes, RF based sources, and helicon sources, when producing plasma over large cross sections and fill volumes. Pulsed argon plasma is produced with quiescence (δnene≪1%) using LAMPS for the duration of 50 ms and a reasonably good radial uniformity (Ln = 210 cm) is achieved. Good axial uniformity is also observed over the entire length of the device. Initial measurements on plasma parameters have yielded plasma density of ∼2×1017m-3 with existing set of filaments. A plasma density of ∼1018 m-3 is envisaged for larger thickness of filaments, such as 0.75 and 1.0 mm, with the existing plasma source assembly setup.

Development of electronic record-keeping software for remote participation in Large Volume Plasma Device upgrade using Angular 2 and NodeJS web technologies.

In an era of digital transformation and collaborations, the Web Information System (WIS) becomes an essential requirement for the information and data sharing of large experimental facilities among users. With the enhancement in the capabilities and performance of web technologies, sharing of experimental data using a flexible, modular, secure, and robust mechanism is feasible. In this direction, the Large Volume Plasma Device (LVPD), an experimental device dedicated for carrying out investigations for unfolding physical phenomena of relevance to Earth's magnetosphere and fusion plasmas, also adopts web-based electronic record keeping for its operation. The nature of investigations is concerned with plasma turbulence of electron scale, induced anomalous plasma transport and mitigation of energetic electrons by excited whistler turbulence that requires large scale, and simultaneous multiple point measurements from different electrostatic and electro-magnetic diagnostics. This paper discusses the WIS implementation in LVPD for the experimental configuration, information logging, and preliminary data analysis. The architecture of the system is spread over three tiers covering application, data, and presentation layers. The presentation layer is developed using the Angular 2 framework on the progressive web application architecture. The application and data layers are developed using NodeJS and PostgreSQL, respectively. The novelty of this paper lies in the integrated application development approach and applicability of the latest web technologies in the scientific and experimental domains. This paper discusses the literature survey of similar developments at other places, requirements, scopes, development artifacts, adapted tools and technologies, obtained results from actual plasma discharges of LVPD, and future enhancements.

Electro-mechanical probe positioning system for large volume plasma device.

An automated electro-mechanical system for the positioning of plasma diagnostics has been designed and implemented in a Large Volume Plasma Device (LVPD). The system consists of 12 electro-mechanical assemblies, which are orchestrated using the Modbus communication protocol on 4-wire RS485 communications to meet the experimental requirements. Each assembly has a lead screw-based mechanical structure, Wilson feed-through-based vacuum interface, bipolar stepper motor, micro-controller-based stepper drive, and optical encoder for online positioning correction of probes. The novelty of the system lies in the orchestration of multiple drives on a single interface, fabrication and installation of the system for a large experimental device like the LVPD, in-house developed software, and adopted architectural practices. The paper discusses the design, description of hardware and software interfaces, and performance results in LVPD.

Citrobacter sepsis in infants.

A study of blood cultures from 320 cases of neonatal sepsis showed 136 (42.5%) to be positive for bacterial growth; of these 82 (60.29%) isolates being gram negative bacilli. Citrobacter was the commonest gram negative bacilli isolated. Other commonly isolated gram negative organisms were Pseudomonas, Klebsiella, Salmonella typhimurium, Acinetobacter and Escherichia coli. Antibiotics susceptibility pattern revealed the isolates to be resistant to commonly used antibiotics.