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Tension leg oil field platforms are a relatively recent concept for oil rigs in that they are made to float (by means of inflatable pontoons) rather than stand on the [...]

We have investigated the influence of an additional bismuth flux during growth on the properties of GaN films prepared by plasma‐assisted molecular beam epitaxy. A wide range of bismuth fluxes have been used, at the highest Bi flux this was larger than the flux of Ga. X‐ray and photoluminescence studies demonstrate that the structural quality and optical properties of the GaN films grown at ∼800 °C are practically unchanged. X‐ray and Auger studies indicated that the concentration of Bi in the bulk of the films grown at ∼800 °C is rather small. We have demonstrated that it is possible to grow conductive metallic Bi films epitaxially onto GaN films in‐situ after epitaxy by reducing the deposition temperature. Bismuth may thus potentially be a new material for in‐situ contacts to GaN layers and device structures.

We have investigated the influence of the growth conditions on the intensity of the blue emission from arsenic doped GaN films grown by plasma-assisted molecular beam epitaxy. We have demonstrated, that for fixed Ga, N and As fluxes there is an optimum growth temperature, at which the highest blue emission intensity is observed. Possible models explaining this effect were discussed.

We have studied the vortex-related phase transition in a number of YBCO thin films that have in-plane anisotropy due to the c-axis lying at an angle to the substrate normal. The critical parameters Tt, z, and ν have been extracted from the scaling of dc I-V measurements made along the two principal transport directions in magnetic fields up to 1 tesla. The dependence of Ttupon the direction of the transport current in some classes of film and the very high z values cast doubt upon the established interpretation based simply upon a vortex liquid–vortex glass phase transition.

When elastomers are exposed to gas at high pressures, the gas enters the elastomers by solution and diffusion processes. If the pressure is removed rapidly, the system becomes supersaturated and gas comes quickly out of solution, causing blistering and fracture of the elastomer (so-called explosive decompression). Factors and some theory involved in the gas ingress and decompression stages are discussed. Data are presented from high pressure permeation measurements, showing deviations from simple predictions, and explosive decompression experiments, showing several forms of failure. Important parameters are seen to be the solubility coefficient of gas in elastomer at the actual pressure, and moduli and tearing energy of the elastomer. However the situation remains one of extreme complexity.

Additive manufacturing is having a dramatic impact on research and industry across multiple sectors, but the production of additively manufactured systems for ultra-high vacuum applications has so far proved elusive and widely been considered impossible. We demonstrate the first additively manufactured vacuum chamber operating at a pressure below 10−10mbar, measured via an ion pump current reading, and show that the corresponding upper limit on the total gas output of the additively manufactured material is 3.6 × 10−13mbar l/(s mm2). The chamber is produced from AlSi10Mg by laser powder bed fusion. Detailed surface analysis reveals that an oxidised, Mg-rich surface layer forms on the additively manufactured material and plays a key role in enabling vacuum compatibility. Our results not only enable lightweight, compact versions of existing systems, but also facilitate rapid prototyping and unlock hitherto inaccessible options in experimental science by removing the constraints that traditional manufacturing considerations impose on component design. This is particularly relevant to the burgeoning field of portable quantum sensors — a point that we illustrate by using the chamber to create a magneto-optical trap for cold 85Rb atoms — and will impact significantly on all application areas of high and ultra-high vacuum.