The gas field ion source (GFIS) is able to generate tightly focused ion beams, which can be used to image or modify a specimen. Among the beam species, helium offers extremely high resolution, however, low sputter yield and sub-surface bubble formation are limiting factors in some applications. Therefore, heavier ions such as neon or nitrogen are used as well. In addition to being a suitable choice for lithographic mask editing, secondary electron (SE) generation by nitrogen beams has been recently shown to be affected by certain types of samples, providing additional contrast compared to helium ions. Here, we report our progress on the study of SE imaging differences between the nitrogen ion microscopy (N2IM) and helium ion microscopy (HIM). SE images of two nano-patterned samples comprising insulator, metal and carbon regions have been imaged by nitrogen and helium ions in two fundamentally different GFIS microscopes. The results corroborate previous reports of significant contrast differences in certain samples caused by the different ion species.
In previous papers a phase field model for λ–transition in 4He was proposed, which is able to describe the influence of the heat flux on the temperature transition. The model presented here generalizes previous results taking into account of a homogeneous presence of quantized vortices below the λ–transition. As parameter that controls the transition, a dimensionless field f linked to the modulus of the condensate wave function is used. In addition to the field f, the resulting model chooses the following field variables: density, velocity, temperature and heat flux. Nonlocal terms to describe inhomogeneities in the field variables and dissipative effects of mechanical and thermal origin are also taken into account. Under the hypothesis that the liquid is at rest, the second sound propagation near the superfluid transition is studied. It is seen that the order parameter modifies the speed and the attenuation of the second sound, as well as the presence of a small tangle of vortices. This shows that the influence of the order parameter is not restricted to the description of the lambda transition, but its presence influences also other features, as the second sound speed and attenuation. In addition to the second sound a new mode is present, corresponding to a perturbation in the order parameter f, which is attenuated within a short number of wavelengths.
Helium-filled hard drives offer improved power efficiency and increased density compared to air-filled hard drives. But what’s the failure rate like for these drives?
Helium-filled hard drives are now all the rage. But how does their reliability stack up compared to regular air-filled hard drives? What better company to answer this question than cloud storage specialists Backblaze. Why is Backblaze the perfect company to answer this question? Because it has a lot of helium- and air-filled hard drives in service. A lot. In the 8- to 12-terabytes storage capacity range the company has 19,065 helium-filled drives in service, along with a further 24,281 air-filled units. Having this many drives in operation allows Backblaze to do some number-crunching and calculate the Annualized Failure Rate (AFR) for the drives. Bottom line — there’s very little difference in AFR between helium-filled hard drives and their air-filled counterparts.
Helium- vs air-filled hard drive failure rates
So does this mean that their failure rate is the same? Andy Klein, Director of Product Marketing at Backblaze, thinks not, and that helium-filled drives will prove to be more reliable if we take into account usage: My hypothesis is that after normalizing the data so that the helium and air-filled drives have the same (or similar) usage (Drive Days), the helium-filled drives we use will continue to have a lower Annualized Failure Rate versus the air-filled drives we use. Another question people wonder about helium-filled hard drives is whether the gas escapes out of the drive? By using the SMART 22 data point, which records the status of helium inside of a hard drive, the company has been monitoring this for three years and has only seen one drive less than 100, with multiple readings between 94 and 99. So the helium escaping doesn’t seem to be a problem.
Springfield Lakes Nature Care president Luise Manning has praised Ipswich City Council’s proposal to ban helium balloons, single-use straws and water bottles.
The council will decide on the new policy in July and if approved the plastics would be ditched from council-sponsored events. Brisbane City Council introduced the same ban last month. Ms Manning said it was encouraging to see the environmental movement catch on. She encouraged Springfield residents to do their part by adding an extra ‘R’ to the long running Reduce, Reuse, Recycle campaign and refuse anything that could not be used more than once. “A straw is a luxury item,” she said. “It’s not the plastic itself that is the problem, it’s the irresponsible disposal of plastic. “We all have to think about landfill and trying to limit what ends up there. “It’s great the council will be able to say ‘At our events we’ll lead the way’.” She said the helium balloon ban was a longtime coming. “I think that should have been done much, much earlier,” said Ms Manning who urged the ban in January last year. “I take no issue with people having helium balloons as decorations at parties indoors, but releasing them in the open air is a nightmare for the environment.” In Queensland, the release of balloons into the environment is considered littering under the Waste Reduction and Recycling Act 2011 — whether released deliberately or by accident. Plastic bags will be banned at shopping centres statewide from July. The ban applies to all retailers including market-stall holders and organisations which supply single-use lightweight plastic shopping bags. Retailers that continue to supply banned bags after July 1 could face a fine of up to $6300 per offence. Queenslanders use almost one billion plastic shopping bags each year.