Amir Izzani Mohamed

Streak Observation System for DC Pre-breakdown Using an Image Guide Scope

A light delay path and a streak camera are combined as a dc pre-breakdown optical observation system. The light delay path in this study is a 20-m-long image guide scope (IGS). The IGS will delay the pre-breakdown light for 100 ns before reaching the streak camera. During this time, the streak camera will be triggered and a streak image of pre-breakdown light can be obtained. Previously, either an image of pre-breakdown light (weak discharge light at either one of the electrode or in the bulk of liquid sample) or an image of complete breakdown light (strong discharge light bridging across the electrodes) could be obtained by using an old system (IGS and a film camera photographic observation system). The transition process from pre-breakdown to complete breakdown light was unknown. The study is dedicated to setup and clarified the combination of the streak camera and IGS system, so that it can be used to clarify the transition process.

Determination of image conversion ratio for Transient Luminous Events (TLEs) observation system

Transient Luminous Events (TLEs) is a type of lightning events occurs at the upper atmosphere or in the D region of the ionosphere during a thunderstorm. The occurring of TLEs is fast and difficult observed by human eyes. Therefore, a camera sensitive to low light condition is needed for observation of this phenomenon. In this paper, the camera is coupled with 50 mm f1.4 lens and Digital Video Recorder (DVR). A conversion of analog-to-digital between personal computer (PC) and the camera was applied to transfer the file by using DVR. This paper covers calculation of the conversion ratio between image dimension in PC monitor to a real dimension for horizontal and vertical axis. In the end of the paper, it is found that the calculated horizontal length is twice as smaller than the actual length and vertical length is 1.92 times smaller than actual length.

Development of a compact and sensitive AC magnetometer for evaluation of magnetic nanoparticles solution

A compact and sensitive AC magnetometer is developed for evaluation of magnetic nanoparticles solution. The developed AC magnetometer consists of two main parts; excitation and detection coil systems. A Helmholtz coil configuration was used as the excitation coil to ensure a high homogeneity of excitation magnetic field. To reduce AC resistance due to eddy current effect in the wire of the excitation coil at a high-frequency region, a Litz wire was used. The Litz wire was composed of 60 strands of copper wires with 0.1-mm diameter. For the detection coil, a first order axial differential coil was used so that environmental noises can be canceled. The detection coil consisted of two 1000-turn copper coils and they were connected in series. The fabricated excitation coil showed a high homogeneity along its axis with the high excitation magnetic field. The sensitivity of the developed system increased with respect to frequency. The magnetic noise of the detection unit showed a 1/f noise characteristic and a sensitivity of 10−10 Am2 at 100 Hz was showed by the developed system. To demonstrate the feasibility of the developed system, harmonics of Nickel nanowires was measured. The harmonics generation increased with the increasing amplitude of excitation field. It can be expected that an extremely sensitive characterization of MNP is possible using the developed system.

DC pre-breakdown light in hexane/low-density polyethylene (LDPE) insulation composites using a long image guide scope and a streak camera

Optical observations on pre-breakdown phenomena of hexane/low-density Polyethylene (LDPE) film insulation composites were carried out by using a system mainly consisted of a streak camera and along image guide scope. The LDPE film was placed on a sphere of point-sphere electrode, which was filled with hexane. The parameters in this study were dc voltage polarity and voltage rises speed. In most cases, under positive polarity voltage regardless of the voltage rises speed, breakdown initiated in the bulk of hexane. While, in most of the case under negative polarity voltage regardless of the voltage rises speed, breakdown initiated at the tip of needle electrode. In most cases, from the obtained streak images, pre-breakdown light developed continuously at the same place where they initiated at least for 10ns. Breakdown voltage was higher under 0.1 kV/s of voltage rises speed as compared to 1.0 kV/s, regardless of the voltage polarity.

Streak observation of DC pre-breakdown light in silicone oil / low-density polyethylene (LDPE) film composites using a long image guide scope

DC breakdown light of silicone oil and LDPE film composites between needle-sphere electrodes with the film placed on sphere electrode was observed using a streak camera. A long image guide scope (IGS) was attached to the streak camera as light delay path. This new system enables us to obtain a streak image of an initial process of the DC breakdown phenomena with a period of 10ns. Under positive polarity voltage, breakdown usually initiated from positive needle in all samples. Initiation of DC breakdown from film side was observed under negative polarity voltage condition.