Harsh Electromagnetic Environment Research Articles

Implementation and testing of the JET gamma-ray cameras neutron filters pneumatic system

Neutron filters/attenuators have been designed and constructed as an upgrade of the JET gamma-ray cameras (GRC's). This diagnostics upgrade should reduce the neutron flux at the gamma-ray detectors in a way that it would make possible gamma-ray imaging measurements in high power deuterium JET pulses, and eventually in deuterium–tritium discharges. The attenuators will be placed within the GRC diagnostics system between the vacuum vessel port and the camera collimator radiation shields in the case of both the horizontal camera and the vertical one and they have to be moved out of the detector line of sight when the neutron/gamma camera diagnostics is used for neutron measurements. The neutron filters will operate in a very harsh electromagnetic environment. It is thus recommended to avoid as much as possible the use of electrical and electronic components for the attenuator steering and control (in particular, for attenuator steering). Therefore a steering and control system based on pneumatic components was designed and constructed. The attenuators together with the steering and control system have been installed on a test stand, which is a 1–1 scale replica of the JET structures where neutron filters are to be installed and successfully tested.

The MIL-STD-1553B data bus: What does the future hold?

Numerous military platforms (land, sea and air) feature serial data bus technology based on the US MIL-STD-1553B data bus standard for integration of their digital systems. Many of these platforms have 15-20 years of operational life remaining, but the installed 1553B data buses (data networks) having only a 1Mbit/sec transfer rate are unable to meet many of the future data networking requirements. Research into new, higher performance data networks has concentrated on modern alternatives with throughput increases of two to three orders of magnitude (100Mbit/sec to 1Gbit/sec). These are generally based on modern commercial-off-the-shelf (COTS) standards, good examples being Ethernet and Fibre Channel. Some are already being employed in military platforms having been ruggedised for the harsh physical and electro-magnetic environment. However these COTS systems while being a natural choice for new platforms may not be cost effective for upgrading older platforms. This paper plots the history of MIL-STD-1553, possibly the most successful military platform standard of all time, and discusses some of the options for increasing its performance and economically extending its life into the future.

Electronic protection and routing optimization of MANETs operating in an electronic warfare environment

Domination of the electromagnetic spectrum is a crucial component of the 21st century warfare. In the harsh electromagnetic environment of the modern battlefield, it is of the utmost importance to deny the opposing force the opportunity to attack or exploit the detection/interception of friendly communications assets through the deployment of electronic protection (EP) measures in order to attain low probability of detection (LPD), low probability of interception (LPI) and anti-jam (A/J). Given that directional antennas are a suitable means to achieve both extended range and LPD/LPI, this paper proposes mechanisms to optimize the trade-off between these capabilities, minimizing the number of hops and end-to-end delay when routing packets in a multi-hop ad-hoc network, while taking into account stealth requirements. The novel scheme is based on a variant of Fisheye State Routing, coupled with a power control algorithm to guarantee a LPD/LPI beyond the zone covered by the omni-directional radiation footprint of the network. The performance of the proposed scheme is evaluated through computer simulation.

Mobile stands for multi-channel high bandwidth acquisition of transient electrical signals

Mobile stands for multi-channel recording of fast transient electrical signals are presented in this paper. The design of the mobile stands and all additionally employed equipment provides efficient shielding against electromagnetic interference and allows carrying out data acquisition in a harsh electromagnetic environment. Some examples are given of the results obtained by means of the data acquisition system based on the mobile stands.

Reconfiguration of flight control systems for actuator failures

We consider the problem of designing fault tolerant control for transient failures in the flight control system caused by harsh electromagnetic environments. We examine principles of fault tolerant design and discuss integrated local supervisory control of these systems. As an example, we present a sample design of a control mixer to achieve fault tolerance in the event of failures in the actuators.

Measurement of Arc‐root velocity of magnetically driven Arcs in switchgear

AbstractThe arc‐root velocity is an important parameter in switchgear devices using magnetically driven arcs for current interruption. Optical measurements of the arc movement may be difficult to accomplish without changing the switchgear device. A simple electrical method for determination of the arc‐root velocity is described in this paper. The arc‐root velocity is represented by the frequency of an electrical signal which makes the measurement highly unaffectable by the harsh electromagnetic environment usually found in switchgear subjected to power tests. The arc‐root velocity can be measured close to the current‐zero passage which is decisive for successful current interruption.

A source of cold molecular ions for Coulomb explosion imaging

A specialized ion source for use in the high voltage terminal of an electrostatic accelerator has been developed to produce vibrationally cold beams of molecular ions. A pulsed valve is used to produce a supersonic expansion of the source gas which is ionized by electron impact near the beginning of the free expansion. Because of the harsh electromagnetic environment in the terminal, special care has been taken to protect the electronic components related to the ion source. The effect of vibrational cooling in the supersonic expansion is demonstrated using Coulomb explosion techniques with a He2+ beam.