Inductive sensor for lightning current measurement fitted in aircraft windows

\u3cp\u3eIn order to retrieve the lightning attachment points, 12 sensors distributed over the aircraft continuously monitor the local electric and magnetic field. The selection of the number and positions of the sensors is described in [4]. The ILDAS is triggered by sudden changes in the field strength in the aircraft. The sensors then determine the local magnetic fields, retaining pre-and post-trigger data over the time span of about 1 s. After landing, the data are compared with possible field distributions derived for a number of current path scenarios [3], and the most likely entry and exit regions are determined.\u3c/p\u3

Lecture demonstrations on transfer impedance

\u3cp\u3eIn our courses the important topic 'transfer impedance' is explained with the help of demonstrations in the class room and in lab assignments. Cables, connectors and equipment are taken as example. The influence of shape, resistance and induction is shown. Measurements in time domain cover the speed range up to several tens of nanoseconds with a conventional square wave generator and oscilloscope. The results are compared to expectations from the theory presented in the course.\u3c/p\u3

Currents and magnetic fields in hollow tubes:an in-class experiment and lab demonstrator for EMC education

\u3cp\u3eThis paper describes a very successful demonstration experiment developed for a course on electromagnetic compatibility at Masters' level at the Eindhoven University of Technology. Such demonstrator plays a big role in teaching both practical concepts and theoretical skills relevant for the topics on cabling, grounding and shielding. The success of the demonstrator relies on several factors, among which: its simplicity, its versatility, its possibility to confront measurements with actual field calculations and on the astonishing fact that these effects occur at 50 Hz. The demonstrator evidences current and magnetic field distributions in a hollow iron tube, for different connection configurations. Some key principles are evidenced, among others: skin effect, proximity effect and the principle of the path of least impedance.\u3c/p\u3

Effects of age on the prevalence of cardiac dysrhythmias in ponies

We investigate structure and evolution of long positive spark breakdown; and we study at which stage pulses of hard x-rays are emitted. Positive high-voltage pulses of standardized lightning impulse wave form of about 1 MV were applied to about 1 m of ambient air. The discharge evolution was imaged with a resolution of tens of nanoseconds with an intensified CCD camera. LaBr3(Ce+) scintillation detectors recorded the x-rays emitted during the process. The voltage and the currents on both electrodes were measured synchronously. All measurements indicate that first a large and dense corona of positive streamers emerges from the high-voltage electrode. When they approach the grounded electrode, negative counter-streamers emerge there, and the emission of hard x-rays coincides with the connection of the positive streamers with the negative counter-streamers. Leaders are seen to form only at later stages

High energy radiation from aircraft-triggered lightning and thunderstorm

In-flight Lightning Strike Damage Assessment System (ILDAS http://ildas.nlr.nl/) was developed in an EU FP6 project to provide information on threat that lightning poses to aircraft. The system contains one E-field and eight H-field sensors distributed over the fuselage. It has recently been extended to include two LaBr3 scintillation detectors. The scintillation detectors are sensitive to x-ray photons above 30 keV. The entire system is installed on an A-350 aircraft. When triggered by lightning and digitizes data synchronously with 10 ns intervals. Twelve continuously monitoring photon energy channels were implemented for X-ray detectors operating at slower rate (15 ms, pulse counting). \u3cbr/\u3eIn spring of 2014 and 2015 the aircraft flew through thunderstorm cells recording the data from the sensors. Total of 93 lightning strikes to the aircraft are recorded. Eighteen of them are also detected by WWLLN network. One strike consists of six individual strokes within 200 ms that were all synchronously identified by WWLLN. The WWLLN inter-stroke distance is much larger than the aircraft movement. Three of these strokes generated X-ray bursts. One exceptionally bright X-ray pulse of more than 8 MeV has been detected in association with another strike; it probably saturated the detector’s photomultiplier. Neither long gamma-ray glow, nor positron annihilation have been detected during the campaign. An explanation is sought in the typical altitude profile of these test flights.\u3cbr/\u3

Inductive sensor for lightning current measurement, fitted in aircraft windows - part I : analysis for a circular window

A novel sensor is described for the detection of the lightning current through the fuselage of an aircraft. The sensor relies on the penetration of the magnetic field through fuselage openings and can be embedded in a window inside the aircraft. The sensor combines good sensitivity with sufficient bandwidth to record the lightning transient current. Guidelines for the position are derived from a mathematical analysis for a circular window

Coupling of open and shielded tracks on printed circuit boards

The DM-CM-DM coupling between tracks of a PCB and the CM circuit formed with a nearby cabinet panel is discussed based on measurements. A\u3cbr/\u3enovel track shielding technique and its consequences for signal transport are presented; intentional partial shielding is discussed

Bliksembescherming voor kritische installaties

Over Nederland gemiddeld is de kans op blikseminslag Ca. 2 tot 4 per jaar per vierkante kilometer. De kans op schade door een directe inslag in een object is tamelijk klein. Veel laagbouw in steden wordt bijvoorbeeld nauwelijks voorzien van een bliksemafleider. Voor hoogbouw of afzonderlijk staande bebouwing is zo’n bescherming echter wel wenselijk. Een afleider biedt de bliksemstroom een pad om het gebouw naar de Aarde . Dit pad wordt primair ontworpen op een lage weerstand. Zo verlaagt men de dissipatie die vooral optreedt tij dens de langdurende volgstromen bij een inslag, en blijft de kans op brand klein