Fast switching of magnetic fields in a magneto-optic trap

Magneto-optic traps which employ current windings to generate pulsed magnetic fields require rapid switch-off times for many applications. Practical difficulties in attaining rapid switch-off of the magnetic field, including the generation of induced currents, are addressed. Several methods for minimizing the switch-off time are presented which do not require complex feedback mechanisms involving direct measurement of the magnetic field

An ion gating, bunching, and potential re-referencing unit

A novel design to achieve the gating, bunching, and potential re-referencing of an ion beam, suitable for use in a photofragment spectrometer, is presented. The device simultaneously performs all three functions in a simple, compact, and easily aligned unit. It requires only a single digital signal and one high voltage supply for operation, and provides higher flux density than previous designs. The unit uses lensing to perform beam gating, an approach which has not been reported previously. The design does not require grids, and does not introduce divergence into the ion beam. Experimental results for the combined gating, bunching, and re-referencing unit are presented, and compared with modeled performance.This work is funded by a Major Equipment Grant from the Australian National University. One of the authors (E.H.R.) is the recipient of an Australian Postgraduate Award

Fast 1 kV metal-oxide-semiconductor field-effect transistor switch

A fast, high-voltage switch based on cheap and readily available components is described. This simple circuit can switch 1 kV to ground with a fall time of ∼2.5 ns, and has proved a cost-effective means of driving electrostatic gating and rereferencing devices in pulsed ion-beam experiments.This work is funded by a Major Equipment Grant from the Australian National University. One of the authors (E.H.R.) is the recipient of an Australian Postgraduate Award

New magnetic dipole transition of the oxygen molecule: Bʹ³Πg←X ³Σg⁻(0,0)

Through the use of isotopically pure gas at a temperature of 77 K, a weak photoabsorption band of ¹⁶O₂ is found near 1856 Å, underlying the stronger Schumann–Runge (SR) band B³Σ−u←X³Σ−g(8,0). The location, structure, and intensity of this new band are consistent with expectation for the magnetic dipole transitionB′ ³Πg←X³Σ−g(0,0), where the designation B′ is chosen to represent the II ³Πg valence state. This electronic transition contributes to the “excess absorption” underlying the SR bands [B. R. Lewis, S. T. Gibson, and E. H. Roberts, J. Chem. Phys. 115, 245 (2001)]

Bright spots as climate-smart marine spatial planning tools for conservation and blue growth

Marine spatial planning that addresses ocean climate-driven change (‘climate-smart MSP’) is a global aspiration to support economic growth, food security and ecosystem sustainability. Ocean climate change (‘CC’) modelling may become a key decision-support tool for MSP, but traditional modelling analysis and communication challenges prevent their broad uptake. We employed MSP-specific ocean climate modelling analyses to inform a real-life MSP process; addressing how nature conservation and fisheries could be adapted to CC. We found that the currently planned distribution of these activities may become unsustainable during the policy's implementation due to CC, leading to a shortfall in its sustainability and blue growth targets. Significant, climate-driven ecosystem-level shifts in ocean components underpinning designated sites and fishing activity were estimated, reflecting different magnitudes of shifts in benthic versus pelagic, and inshore versus offshore habitats. Supporting adaptation, we then identified: CC refugia (areas where the ecosystem remains within the boundaries of its present state); CC hotspots (where climate drives the ecosystem towards a new state, inconsistent with each sectors’ present use distribution); and for the first time, identified bright spots (areas where oceanographic processes drive range expansion opportunities that may support sustainable growth in the medium term). We thus create the means to: identify where sector-relevant ecosystem change is attributable to CC; incorporate resilient delivery of conservation and sustainable ecosystem management aims into MSP; and to harness opportunities for blue growth where they exist. Capturing CC bright spots alongside refugia within protected areas may present important opportunities to meet sustainability targets while helping support the fishing sector in a changing climate. By capitalizing on the natural distribution of climate resilience within ocean ecosystems, such climate-adaptive spatial management strategies could be seen as nature-based solutions to limit the impact of CC on ocean ecosystems and dependent blue economy sectors, paving the way for climate-smart MSP

Bright spots as climate‐smart marine spatial planning tools for conservation and blue growth

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