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For reaching very high magnetic fields in fully superconducting magnets, beyond 16 T for particle accelerators dipoles and beyond 23 T for solenoids, the use of high-temperature superconductors (HTS) is unavoidable. Due to the high minimum quench energy in HTS these coils are much more difficult to protect against quenches using conventional methods, such as quench heaters or coupling loss induced quench (CLIQ). Although it is possible to use a dump resistor on a short HTS magnet, extracting the energy externally, this does not provide a solution for longer magnets or magnets operated in a string, because the extraction voltage becomes unacceptably high. Here, a method named E 3 SPreSSO (External Energy Extraction Symbiotic Protection System for Series Operation) is proposed that allows for fast energy extraction in HTS magnets. The E 3 SPreSSO comprises of units with a near-zero self-inductance superconducting circuit, connected in series with the main magnet. When the protection is triggered, these devices are turned resistive, using quench heaters, overcurrent or CLIQ, causing them to absorb the energy of the system. The units can be located outside the main magnet and do not generate magnetic field. Therefore, it is possible to use relatively cost-efficient and robust Nb-Ti or possibly MgB 2 (at higher temperatures). This paper introduces the concept and provides an analytical method weighing the different options for designing the E 3 SPreSSO units themselves.

In the framework of the high-luminosity upgrade of the large hadron collider, the U.S. LARP collaboration and CERN are jointly developing a 150-mm aperture Nb3Sn quadrupole for the Large Hadron Collider (LHC) interaction regions. Due to the large beam size and orbit displacement in the final focusing triplet, MQXF has challenging targets for field quality at nominal operation conditions. Three short model magnets have been tested and around 30 coils have been built, allowing a first analysis of the reproducibility of the coil size and turns positioning. The impact of the coil shimming on field quality is evaluated, with special emphasis on the warm magnetic measurements and the correlation to field measurements at cold and nominal field. The variability of the field harmonics along the magnet axis is studied by means of a Monte-Carlo analysis and the effects of the corrective actions implemented to suppress the low-order unallowed multipoles are discussed.

During 2016, one-quarter of the LHC main dipoles have has been powered above the 7.7 T operational field, to reach a field of 8.1 T. These tests were done to confirm the extrapolation of the training behavior based on a Gaussian tail of the quench distribution. In this paper, it is shown that a modified Gaussian distribution can be used to better model the quench distributions. We then present the data above 6.5 TeV, showing that they are compatible with the previous expectations. We present the data of retraining of sector 12, which was warmed up in 2016 to replace a magnet, and training of individual magnets that went through several thermal cycles: there is an indication that training campaigns during successive warm-ups and cool-downs could become shorter. We finally show that a significant correlation is found between the training of the installed magnet and individual test after a thermal cycle (second cool-down). On the other hand, no correlation is found with individual test under virgin conditions (first cool-down).

The large hadron collider (LHC) at CERN has been operating and generating physics experimental data since September 2008, and following its first long shut down, it has entered a second, 4-year-long physics run. It is to date the largest superconducting installation ever built, counting over 9000 magnets along its 27-km long circumference. A significant operational experience has been accumulated, including the occurrence and consequences of electrical faults at the level of the superconducting magnets, as well as their protection and instrumentation circuits. The purpose of this paper is to provide a first overview of the most common electrical faults and their frequency of occurrence in the first years of operation, and to perform a statistical analysis that can provide reference values for future productions of similar dimensions and nature.

The large hadron collider (LHC) upgrade, called high-luminosity LHC is planned for the next decade. A wide range of magnets and new technologies are currently under development. One of these systems will be a set of twin aperture beam orbit correctors positioned on the approaches to the ATLAS and CMS experiments. This twin aperture magnet system comprising 16 magnets, approximately 2 m long, with large 105-mm clear aperture coils. Each aperture will independently deliver 5-T⋅m integral field, between apertures the field vectors are rotated by 90° from each other, and individually powered. This paper presents the sequence of component developments to produce a cost-effective canted cosine theta model magnet. We describe the challenges encountered during the manufacture of the coil formers with their helical canted coil winding process which places a number of insulated wires into the 2-mm-wide 5-mm-deep slot. We describe the: pressurized impregnation process, multiple jointing to connect inner and outer sets of wires within the confines of the coil assembly, and magnet assembly into support structure and yoke. Finally, we present the quench performance and initial test results of this novel coil configuration.

In 2015, the 1232 Nb-Ti dipole magnets in the Large Hadron Collider (LHC) have been commissioned to 7.8 T operational field, with 172 quenches. More than 80% of these quenches occurred in the magnets of one of the three cold mass assemblers (3000 series), confirming what was already observed in 2008. In this paper, the recent analysis carried out on the quench performance of the Large Hadron Collider dipole magnets is reported, including the individual reception tests and the 2008 and 2015 commissioning campaigns, to better understand the above-mentioned anomaly and give an outlook for future operation and possible increase of the operational field. The lower part of the quench probability spectrum is compatible with Gaussian distributions; therefore, the training curve can be fit through error functions. An essential ingredient in this analysis is the estimate of the error to be associated with the training data due to sampling of rare events, allowing to test different hypothesis. Using this approach, an estimate of the number of quenches required to reach 8.3 T (corresponding to the 7 TeV nominal energy) is given, and we propose to have two LHC sectors trained toward this target before the next warm up of the LHC.

As part of the Large Hadron Collider Luminosity upgrade (HiLumi-LHC) program, the US LARP collaboration and CERN are working together to design and build a 150 mm aperture Nb$_{3}$Sn quadrupole for the LHC interaction regions. A first series of 1.5 m long coils were fabricated and assembled in a first short model. A detailed visual inspection of the coils was carried out to investigate cable dimensional changes during heat treatment and the position of the windings in the coil straight section and in the end region. The analyses allow identifying a set of design changes which, combined with a fine tune of the cable geometry and a field quality optimization, were implemented in a new, second-generation, coil design. In this paper we review the main characteristics of the first generation coils, describe the modification in coil lay-out, and discuss their impact on parts design and magnet analysis. As part of the Large Hadron Collider (LHC) Luminosity upgrade program, the U.S.-LHC Accelerator Research Program collaboration and CERN are working together to design and build a 150-mm aperture Nb_3Sn quadrupole for the LHC interaction regions. A first series of 1.5-m-long coils was fabricated and assembled in a first short model. A detailed visual inspection of the coils was carried out to investigate cable dimensional changes during heat treatment and the position of the windings in the coil straight section and in the end region. The analyses allow identifying a set of design changes which, combined with a fine tune of the cable geometry and a field quality optimization, were implemented in a new second-generation coil design. In this paper, we review the main characteristics of the first generation coils, describe the modification in coil layout and discuss their impact on parts design and magnet analysis.

By combining a wide range of systems and technologies, Kongsberg has recently produced a complete, integrated turnkey solution for very high resolution wide-swath real-time acoustic imaging and bathymetry. Named Cassandra, the system is suitable for platforms such as towed systems, large ROVs and other submersibles. Core components include modular sonar receiver arrays; a high-resolution multibeam echo sounder as a gap filler; an aided inertial navigation system; a real-time synthetic aperture sonar (SAS) processing engine for imagery and bathymetry; as well as an integrated control and visualization system. Full-swath high-resolution real-time SAS bathymetry has been developed as part of the project. The method is based on cross-correlation of motion-compensated wavenumber-domain SAS imagery from two vertically separated receiver arrays.

The Large Hadron Collider (LHC) contains eight main dipole circuits, each of them with 154 dipole magnets powered in series. These 15-m-long magnets are wound from Nb-Ti superconducting Rutherford cables, and have active quench detection triggering heaters to quickly force the transition of the coil to the normal conducting state in case of a quench, and hence reduce the hot spot temperature. During the reception tests in 2002-2007, all these magnets have been trained up to at least 12 kA, corresponding to a beam energy of 7.1 TeV. After installation in the accelerator, the circuits have been operated at reduced currents of up to 6.8 kA, from 2010 to 2013, corresponding to a beam energy of 4 TeV. After the first long shutdown of 2013-2014, the LHC runs at 6.5 TeV, requiring a dipole magnet current of 11.0 kA. A significant number of training quenches were needed to bring the 1232 magnets up to this current. In this paper, the circuit behavior in case of a quench is presented, as well as the quench training as compared to the initial training during the reception tests of the individual magnets.

The Norwegian Coastal Administration (NCA) is responsible for monitoring the environmental risk created by shipwrecks in Norwegian waters. If the risk is found to be unacceptable, corrective measures will be recommended to the Norwegian Ministry of Fisheries and Coastal Affaires. Approval and funding of such corrective measures will be decided by the Ministry.The NCA has been tasked to execute a program to find the shipwrecks that constitute the highest environmental risk from substances other than oil. The NCA’s Wreck Data Base (2,300 wrecks) is the basis for the study.The emphasis of this article is on activities connected to ships loaded with chemical weapons (CWs) dumped in the Skagerrak. The article gives information on the surveys carried out by the Norwegian Defense Research Establishment (FFI) in 1989 and 2002. A number of the wrecks containing CWs are unaccounted for. FFI recommended in the 2002 report that an effort should be made to find the remaining CW wrecks. To find and possibly identify the missing CW wrecks in Skagerrak, a search program will be developed. The NCA is testing a new concept this autumn: is it possible to identify a sunken ship by class or name based on information from an underwater vehicle? The test of FFI’s HUGIN 1000 HUS autonomous underwater vehicle is expected to provide information on the suitability of the vehicle in providing data for wreck location and identification.

The field strength and homogeneity of all the LHC superconducting magnets were measured as a part of the production control and qualification process that has taken place during the past four years. In addition to field measurements at room temperature performed on the integral of the production, a significant part of the magnets has been subjected to extensive magnetic measurements at cold. The measurements at cryogenic temperatures, generally performed up to excitation currents of 12 kA corresponding to the ultimate LHC energy of 7.6 TeV, were mainly based on static and dynamic field integral and harmonic measurements. This allowed us to study in detail the DC effects from persistent current magnetization and long-term decay during constant current excitation. These effects are all expected to be of relevance for the field setting and error compensation in the LHC. This paper reports the main results obtained during these tests executed at operating conditions. The integrated field quality is discussed in terms of distribution (average and spread) of the field strength and low-order harmonics as obtained for all the main ring magnet families (dipoles, main and matching quadrupoles). The dependence of field quality on coil geometry, magnet and cable manufacturer is analyzed. A projection of the field quality expected for the critical components in the machine is presented., peer-reviewed

The current generations of the HUGIN autonomous underwater vehicles (AUVs) have been used in a number of Rapid Environmental Assessment (REA) missions over the past few years, including participation in several national and international military exercises and operations. This article discusses some of the main advantages and limitations of using AUVs in REA operations. This is followed by examples from actual operations that illustrate the choices and trade-offs that must be made. The article aims to demonstrate that AUVs are mature enough for many types of REA operations.

In August 2006, about 95 % of the production of the 1232 LHC superconducting dipole cold masses, whose coils are wound with Cu/Nb-Ti cables, is completed. One of the 3 manufacturers, having produced one third of the required magnets, completed its production in the end of 2005. The acceptance of the magnets takes place after the 1.9 K performance tests and has been issued for more then 1000 magnets so far. More then half of the dipole magnets are already installed in the tunnel. The paper reviews the main features of the dipoles, the most important steps of the manufacturing and the most critical operations. The quality control and the critical nonconformities that have led, for instance, to a swift campaign of investigations and repairs of few subcomponents (diode assembly, cold bore tube to welding flare fillet weld) are discussed. The status of the production and the performance of the tested dipoles will be presented. Finally the expected schedule for the completion of the production will be shown.

The main issues concerning the field quality in the main quadrupoles of the Large Hadron Collider are presented. We show the trend plots for the focusing strength and multipoles at room temperature covering more than 2/3 of the production. We describe the correction of the coil layout to improve b6 at injection field level. A non-negligible fraction of the quadrupoles has been manufactured with collars featuring a magnetic permeability somewhat higher than the specified limits. We show plots for this anomaly. Field quality correlations to measurements in operational conditions are discussed. The dependence of field quality on cable manufacturer is analysed

By the end of August 2005 about 320 of the 400 main LHC quadrupole magnets have been fabricated and about 220 of them assembled into their cold masses, together with corrector magnets. About 130 of them have been cold tested in their cryostats and most of the quadrupoles exceeded their nominal excitation, i.e. 12,000 A, after no more than two training quenches. During this series fabrication, the quality of the magnets and cold masses was thoroughly monitored by means of warm magnetic field measurements, of strict geometrical checking, and of various electrical verifications. A number of modifications were introduced in order to improve the magnet fabrication, mainly correction of the coil geometry for achieving the specified field quality and measures for avoiding coil insulation problems. Further changes concern the electrical connectivity and insulation of instrumentation, and of the corrector magnets inside the cold masses. The contact resistances for the bus-bar connections to the quench protection diodes and the elimination of insulation problems of the main bus-bars required special attention. To this must be added actions for solving of interface problems to the neighbouring magnets in the machine and to the cryogenic feed line.

More than two thirds of the dipoles of the Large Hadron Collider have been manufactured and their magnetic field has been measured at room temperature. In this paper we make a review of the trends that have been observed during the production. In some cases, the trends were traced back to displacements of conductors with respect to the nominal lay-out. The analysis allows detecting the most critical zones in the superconducting coil as far as field quality is concerned. The second part of the paper makes the point of the observed differences in field quality between the three manufacturers. The analysis allows evaluating which multipoles are more affected, what magnitudes of displacements are necessary to explain these differences (the manufacturers all producing the same baseline), and what could be the origin of such differences

An autonomous underwater vehicle for mine reconnaissance is currently being developed by the Norwegian Defence Research Establishment. The system will detect and accurately locate mine-like objects through a systematic, autonomous survey of an area of interest. Multibeam echo sounder data from various dummy mine objects have been collected during several sea trials with HUGIN and other platforms. These real sensor data have been used for evaluation of sensor performance and for developing algorithms for automatic object enhancement and detection. The mine reconnaissance concept will be demonstrated early 2001 with a HUGIN vehicle carrying a minimal mine detection sensor configuration consisting of a side-scan sonar and a multibeam echo sounder. The sensor suite, together with the level of adaptive behaviour, will be upgraded in later versions.

This paper presents an integrated INS (Inertial Navigation System) and camera-based navigation system. The camera-based navigation system provides position measurement aiding to the INS. This is an alternative to the more conventional GPS (Global Positioning System) aided INS. The system is intended for UAVs (Unmanned Aerial Vehicles) and long-range missiles. The basic principles of camera-based navigation are presented. The Kalman filter based integration of INS and camera-based navigation is discussed. Total system simulation results are shown together with INS simulations for comparison. Finally, a brief overview of factors that improve the navigation accuracy is presented.

After two years of shutdown, the Large Hadron Collider (LHC) operated in 2015 at an energy of 6.5 TeV. In this paper, we give the first outlook of the behavior of the LHC magnets operating at this field level, corresponding to 8-T peak field in the main dipoles. The main magnetic features are reconstructed through the beam measurements, mainly the tune (quadrupolar components) and the chromaticity (sextupolar components). The decay and snapback at injection and the start of the ramp are expected to increase by 50% due to the higher operational current. The behavior at high field will be affected by the saturation components, which were barely visible in one magnet family in the 4-TeV runs and totally invisible in the rest. Although the initial plan aims at a rather conservative value of β*, during the squeeze, the triplet and matching section quadrupole will become important. Beam measurements will provide interesting information about the magnetic behavior of these quadrupoles; in particular, through beta beating, we will estimate the absolute precision of the knowledge of the quadrupole strength. The statistics of the beam measurements will be rather limited in the first stages of commissioning, but should already reveal the main features of the 6.5-TeV operation.

We present a comparison between the electromagnetic model of the main LHC magnets and the magnetic measurements carried out during production. The goal of this study is to test the validity range of the model and to uncover discrepancies between models and reality. We de-compose the field computation into several parts: geometry (coils, collars, and yoke), persistent currents in the superconducting cables, and saturation of the iron yoke. For each component we give the agreement between model and measurements. This gives an indication about the precision one can expect to obtain from a simulation code - this information is particularly relevant for future upgrades of the LHC

Like traditional side scan sonars, synthetic aperture sonar (SAS) systems have a coverage gap in an area directly underneath the sensor. Range resolution projected onto the seafloor deteriorates near the vertical, and objects do not cast shadows. Furthermore, to limit multipath in shallow water, some SAS systems do not transmit or receive at all near the vertical. It is difficult to come up with a sensor that can match the performance of a good SAS for the area around nadir - at least without increasing the cost and complexity of the system substantially, or imposing strict limits on operation. This paper investigates four possible technologies as gap fillers for SAS; acoustic as well as optical systems.

Underwater vehicles are used in a wide range of tasks in various sectors. Cost-effective and accurate seabed surveying and mapping using autonomous underwater vehicles (AUVs) have been carried out for years in the offshore oil and gas sector. Much of the experience gained is now being benefited upon in new and challenging applications. One of the emerging AUV applications is hydrographic surveying (e.g. for creating nautical charts), particularly in waters shallower than 100 m. Key factors for mission-success include obtainable accuracy and resolution of the final digital terrain model (DTM), as well as the feature detection capability of the integrated system. This paper gives an in-depth discussion and analysis of the horizontal mapping accuracy achievable by integrated, state-of-the-art hydrographic AUV systems. The HUGIN 1000 AUV fitted with interferometric synthetic aperture sonar (SAS) is used as a case study, and the system accuracy as assessed in detail – starting from surface navigation, going all the way down to the acoustic seabed footprint. A discussion is given at the end on the feasibility of AUVs in terms of the minimum standards proposed by the International Hydrographic Organization (IHO).

Accurate and reliable inspection of subsea pipelines traditionally requires the use of multiple sensors, which again have different requirements for range and geometry. This makes pipeline inspection a time consuming and costly process. The use of high resolution synthetic aperture sonar (SAS) can potentially change this substantially. Current state of the art interferometric SAS systems offer very high resolution imagery and bathymetry over a very wide swath. Mounted on an autonomous underwater vehicle (AUV), such a system can provide highly detailed data sets of a pipeline with just one or two passes - either fully autonomously, or with operator supervision as desired. In June 2009, a Kongsberg Maritime HUGIN 1000-MR AUV equipped with a HISAS 1030 interferometric SAS performed such a pipeline inspection mission in Western Norway. The paper will show examples of the data recorded during the above mission.

Optics stability during all phases of operation is crucial for the LHC. Tools and procedures have been developed for rapid checks of beta beating, dispersion, and linear coupling, as well as for prompt optics corrections. Important optics errors during the different phases of the beam commissioning were observed and locally corrected using the segment-by-segment technique. The most relevant corrections at injection have been corroborated with dedicated magnetic measurements.

Navigation of underwater vehicles has been and remains a substantial challenge to all platforms. The need for improved accuracy and robustness, sustainability, and de-risking develops with the emergence of new applications, and with the growing acceptance of autonomous underwater vehicles (AUVs) in both military and civilian institutions. One of the main driving factors is the ability to carry out long-duration missions fully autonomous and without supervision from a surface ship. Combined with inertial navigation, the use of one or several transponders on the seabed is an accurate and cost-effective approach toward solving several of these challenges. The principle discussed in this paper is called underwater transponder positioning (UTP), and requires only one transponder due to tight coupling with the inertial navigation system (INS). For many scenarios UTP may be a better alternative than using a long baseline (LBL) system. This paper reports in-situ and post-processed navigation results obtained with a state-of-the-art UTP aided INS, onboard a HUGIN 1000 AUV. The results demonstrate the feasibility of UTP in large-scale autonomous operations. Excellent realtime navigation is achieved, and the accuracy obtained in postprocessing is shown to be close to that obtained when aiding the INS with an ultra-short baseline (USBL) positioning system.

Synthetic aperture sonar (SAS) has been proven to work by a variety of groups — first on towed vehicles, later on AUVs — but still faces substantial scepticism among potential users, especially regarding the robustness of the technology. This is at least partially due to a number of inherently non-robust systems that have been fielded over the past decade. SAS systems have failed to reach their target performance for reasons ranging from the design, capabilities and configuration of the sonar, via the processing chain, to characteristics of the host platform such as motion instability, and the navigation system employed. This article attempts to systematize and describe the most common pitfalls, and how they can be avoided.

Synthetic aperture sonar (SAS) can produce images with centimetre-level resolution and area coverage of better than one square kilometer per hour. This makes SAS an ideal sensor for detection and classification of small targets over large areas. Fully automated target analysis allows improved autonomy when using autonomous underwater vehicles (AUVs) and saves a tedious manual analysis in post-mission analysis. Recognition of small targets in sonar imagery is, however, a difficult task. SAS imagery preserves wavenumber information. This gives the possibility for extra products in addition to high resolution imagery. We propose a two-stage processing where regions of interest are generated from reduced resolution SAS imagery and subsequently post processed images are used to generate relevant target analysis information. In this paper, we concentrate on the types of information available and their significance rather than the choice of intermediate resolution and initial detection methods. The extra processing products discussed in this paper are target-enhanced images by autofocus, shadow-enhanced images by fixed focusing, multi-aspect images, frequency-selective information and 3D shape from interferometry. We show examples of each of the additional products using data collected by the HISAS 1030 interferometric SAS carried by the HUGIN 1000-MR vehicle.

Autonomous underwater vehicles are gaining acceptance in a number of applications and countries, as a safe, cost-effective and reliable alternative to manned or remotely controlled systems. However, the actual autonomy of these vehicles is limited in many ways, restricting their potential uses. Further advances in AUV autonomy will enable new operations, such as very long endurance missions (weeks), and operations in unknown areas. While some experimentation is already taking place with e.g. under ice operations, the chance of failure is unacceptably high for many potential users. De-risking of long- endurance autonomous operations in unknown areas is thus an important goal for the AUV community. This paper gives an overview of the AUV research being carried out towards this end at the Norwegian Defence Research Establishment.

This article presents the formulae and some "rules of thumb" for computing basic performance parameters of synthetic aperture sonar (SAS) systems, with references to relevant literature. Comparisons with traditional side scan sonar (SSS) are given where appropriate. The article then discusses SAS survey patterns and area coverage rate, and presents arguments for and against the addition of a gap filler sensor. Emphasis is placed on multi-element, high-resolution SAS for autonomous underwater vehicles (AUVs), but the principles are in general transferable to other sensors and platforms.

The Norwegian Defence Research Establishment (FFI) and Kongsberg Maritime AS have an ongoing program to develop synthetic aperture sonar (SAS) technology for the HUGIN autonomous underwater vehicle (AUV). This includes the development of a high-resolution multi-aspect interferometric SAS, named SENSOTEK, which has been installed on HUGIN I. During this project, FFI has developed a full suite of software for postprocessing of SAS data, named "FOCUS Synthetic Aperture Sonar Signal Processing Toolbox". The toolbox includes integrated DPCA and INS navigation, beamforming both in time and wavenumber domain, autofocusing by map drift and contrast optimization, and seafloor height estimation by cross correlation techniques and interferometry.

Since 2001, the Royal Norwegian Navy (RNoN) Mine Warfare Flotilla have used HUGIN AUVs in a number of military operations around Europe. A dedicated military system, HUGIN 1000, was delivered to the Flotilla in January 2004. The AUV is operated from an RNoN mine hunter, and has been deployed in NATOs Immediate Reaction Force MCMFORNORTH from October 2004. Various types of operations have been performed, ranging from route surveys to covert mine reconnaissance and rapid environmental assessment (REA) missions. Equipped with side scan or synthetic aperture sonar, multibeam echo sounder, and a state of the art integrated inertial navigation system, the HUGIN AUVs provide high quality, high resolution imagery and bathymetry with excellent position accuracy. A proven launch and recovery system allows safe and efficient operation in high sea states. In parallel with the use of the HUGIN 1000 system in the RNoN, a new version with further improved capability is being developed. Lessons learned during four years of operational military use of HUGIN vehicles will help form the next generation, called HUGIN 1000-MR. Purchase of this system has been approved by the Norwegian Ministry of Defence, and delivery is expected in 2006.

A flexible and extensible payload system has been developed for the HUGIN family of autonomous underwater vehicles (AUVs). An important feature of the system is that it allows the HUGIN developers, the payload developers, or a third party, to develop interface software for each payload. The software is integrated in such a way that the vehicle operators can then mix and match payloads integrated by different parties. The HUGIN payload system has been used extensively in commercial missions over the last years, and the number of supported payloads is steadily growing. This paper explains the design of the subsea and topside segments of the payload system, and describes some of the important aspects of payload system integration in an AUV.

The HUGIN untethered underwater vehicle (UUV) system is the result of a highly focused development program to provide a cost-effective tool for the offshore industry for high performance topographical seabed mapping and imaging. HUGIN is presently operated on a regular basis, providing commercial survey services to the off shore and scientific communities. The technology also holds great promise in future resource management and naval operations, being a hydrodynamically stable untethered platform that can carry a multitude of sensor systems and be operated ahead of or completely independent of surface ships. This paper describes the basic features of the HUGIN system and gives examples of practical results obtained from survey operations, maritime science data gathering, and deep water mine hunting research.

In January 2003, the Royal Norwegian Navy (RNoN) directed the Norwegian Defence Research Establishment (FFI) to deliver a prototype AUV suitable for various military applications by the end of the year. The vehicle, developed by FFI and Kongsberg Simrad AS, will be the first of the new HUGIN 1000 AUV class, and builds extensively on technologies and solutions from the larger HUGIN 3000 vehicle class. Primary applications for HUGIN 1000 include mine reconnaissance, depth independent mine detection, classification and localisation, MCM route survey, as well as overt and covert rapid environmental assessment (REA). HUGIN 1000 is highly modular, and in its standard configuration will have an endurance of approximately 24 hours. A substantially similar version will also be available for civilian customers.

As part of the HUGIN AUV/UUV development program, the Norwegian Defence Research Establishment (FFI) has developed a suite of computer programs for mission planning, control and supervision. The software has been used on thousands of HUGIN missions for more than 5 years. The feedback from the development, scientific and commercial HUGIN operators has been and continues to be used for continuous refinement and extension of the software.

The eight papers in this special issue focus on synthetic aperture sonar. The focus is on signal processing and performance characterization for synthetic aperture imaging sonars, with emphasis on systems that operate in stripmap mode--a monostatic approach utilizing broadside beams, and which represents the majority of designs currently seeing practical application.

The design and construction of a 120-mm wide-aperture, Nb-Ti superconducting quadrupole magnet for the Large Hadron Collider (LHC) insertion region is part of a study towards a luminosity upgrade of the LHC at CERN, envisaged for 2020-22. The main challenges for this accelerator quality magnet are to operate reliably with the high heat and radiation loads that are predicted in the insertion magnet regions. Calculations give approximately 500 Watts over the 30-m-long string of insertion magnets, while today LHC is operating for a nominal heat load of 12 Watts. To extract this heat, the model magnets incorporate new features: Open cable insulation, open ground insulation, open magnet structure, and a quench heater that has open channels to help extract the steady state heat load. This paper presents results from tests at room temperature and 1.8 K for the initial model magnet. We report magnet training, transfer function and field quality measurements, quench heater performance, and heat extraction studies using imbedded heaters to simulate the deposited beam heating profile.