Since the installation of an ITER-like wall, the JET programme has focused on the consolidation of ITER design choices and the preparation for ITER operation, with a specific emphasis given to the bulk tungsten melt experiment, which has been crucial for the final decision on the material choice for the day-one tungsten divertor in ITER. Integrated scenarios have been progressed with the re-establishment of long-pulse, high-confinement H-modes by optimizing the magnetic configuration and the use of ICRH to avoid tungsten impurity accumulation. Stationary discharges with detached divertor conditions and small edge localized modes have been demonstrated by nitrogen seeding. The differences in confinement and pedestal behaviour before and after the ITER-like wall installation have been better characterized towards the development of high fusion yield scenarios in DT. Post-mortem analyses of the plasma-facing components have confirmed the previously reported low fuel retention obtained by gas balance and shown that the pattern of deposition within the divertor has changed significantly with respect to the JET carbon wall campaigns due to the absence of thermally activated chemical erosion of beryllium in contrast to carbon. Transport to remote areas is almost absent and two orders of magnitude less material is found in the divertor.

Studies were made of accurate, total field aeromagnetic data of excellent uniformity over an area in NW. Ontario extending from 4845'N to 53N latitude and from 86W to 94W longitude. The rocks in this area are of early Precambrian age (Archaean era). The regional effects from the data were removed. The residual values were then analytically filtered to obtain the total field stripped of its near-surface, high amplitude components. Eighty-five individual anomalies were selected and analyzed to determine the horizontal dimensions and the depths to the tops and bottoms of the causative bodies and the magnitude and direction of total polarization vectors associated with the bodies. The bodies were assumed to be vertical rectangular prisms of arbitrary polarization. A brief summary of the method used is presented.The horizontal dimensions of the bodies vary from 0.8 km (.5 milez to 5.1 kms (3.2 miles). The depths to the top of the bodies in the filtered aeromagnetic map are found to be in the range 4.8 kms (3 miles) to 8 kms (5 miles) from the surface of the ground. The depths to the bottom of the bodies are between 17.7 kms (11 miles) and 24 kms (15 miles) for most of the anomalies, with a mean depth of 20 kms (12.4 miles), which is interpreted as the mean depth to the Curie point geotherm. The horizontal vectors of the polarizations are subparallel to the magnetic lineation of the filtered aeromagnetic map. An interesting and surprising result of this analysis is the detection of the presence of alternatingly normal and reverse polarization roughly in the East-West direction. The mean inclination and declination for normal polarizations are 67.6 and 258.7 respectively whereas those for reverse polarizations are -67.9 and 81.3 respectively. The consistency in the directions of magnetization in the two clusters for normal and reverse polarization indicates strongly the absence of any dominant component of magnetization parallel to the present field. On the basis that the magnetizations are permanent and the reversals are due to field or selfreversal, the calculated pole position for the rocks of Archaean era is found to be at a latitude of 31.5 N and a longitude of 136.9 W. The intensity of magnetization of the bodies lies within a wide range from. 0006 to. 349 cgs emu with the average of. 055 cgs emu.

The aeromagnetic survey operations of the Geological Survey of Canada (GSC) began in 1946, utilizing a magnetometer in a bird system towed by a Royal Canadian Air Force Anson. Subsequent early operations were carried out by the GSC-operated Canso and Aero Commander aircraft. In 1961, the GSC in-house survey team formed the nucleus of a contract surveys group set up to monitor a new program established to complete the aeromagnetic mapping of the Canadian Shield in 12 years on a cost-sharing basis with the provinces. Today, surveys are carried out under contract by light twin-engine aircraft such as the Cessna 404 and even, in some cases, single-engine aircraft that utilize compact computer-controlled data acquisition and navigation systems and inboard magnetometer installations. Early systems were capable of resolution of only a few nanoteslas (nT) compared to the current standard of 0.1 nT or less, and flight path positioning with 35 mm film and photomosaics or topographical maps was extremely challenging. Despite these limitations, the careful selection of survey parameters and attention given to quality control have resulted in a world-class aeromagnetic data base that has contributed significantly to regional geological mapping and to mineral and oil exploration in Canada. Concurrently, the GSC carried out research programs into the development of instrumentation and into processing, interpretation, and enhancement techniques. In 1968, the GSC acquired its own platform, a Beechcraft B80 Queenair, which was used to develop high-sensitivity techniques, and an inboard gradiometer system, which was transferred to private industry in 1983. The GSC, in cooperation with the Flight Research Laboratory of the National Research Council of Canada, has also conducted a program of research into magnetometry and navigation combined with aeromagnetic studies of the Arctic since 1962.

Aeromagnetic surveying within the auroral zone is complicated by the high incidence of severe magnetic disturbance. Although corrections for the time variations could be made by means of data obtained from a ground station located centrally within the survey area, the areal extent over which such corrections would be valid is not known. The paper gives magnetic‐disturbance data obtained from two simultaneously operated ground stations, placed initially 130 mi apart (209 km), and later 87 mi (140 km) apart, within the auroral zone. It is found that such corrections would be seriously in error for separations of this order between ground and air stations.

The idea of writing a historical paper is new to me. All I can hope to do is to give my own subjective slant, as I saw things develop in the period from 1938, when I first became interested in geophysics, to 1965, when I left the field to work in remote sensing (in which I have been engaged ever since). When I talk about geophysics, from which I have been away for so long, I feel like Rip Van Winkle, who fell asleep for 20 years.