November 05, 2008

New Metamaterial Could be Affordable and High Volume and Small Magnetosphere Radiation Protection for Space Travellers

There were two interesting developments in physics :

1. higher volume metamaterial production could enable practical uses out of the lab and

2.small magnetosphere (several hundred of meters instead of 100+ kilometers wide) radiation protection for space travellers. This could enable light weight and safe protection for astronauts going to Mars.

The minimagnetosphere system is no bigger than a large desk and uses the same energy as an electric kettle. Two mini-magnetospheres will be contained within two mini satellites located outside the spaceship. Should there be an increase in solar wind flux, or an approaching cloud of energetic particles from a flare and/or coronal mass ejection (CME), the magnetospheres can be switched on and the solar ions are deflected away from the spacecraft.

Higher Volume and Cheaper Metamaterials Produce Bottom Up
Ars Technica report on the metamaterials.

In a step that may help move metamaterials out of the lab, a new negative-index metamaterial has been developed, one with a novel structure that can be made using cheaper "bottom-up" fabrication techniques. The hallmark of a negative-index metamaterial is its precise array of nanostructures, which can interact with electromagnetic waves in a controlled manner. This demands precision fabrication that is generally accomplished with a top-down approach. Fabricating a structure with nanoscale precision using top-down methods requires exotic equipment and a lot of time—neither of which are desirable for getting that material into the real world.

The chinese researchers of Northwestern Polytechnical University Xi'an, China, ended up with was a material system that is nothing like earlier negative-index metamaterials: silver dendritic cells or, more simply, silver snowflakes.

By controlling the conditions of dendritic growth on a glass substrate and then examining the results, researchers were able to identify silver dendrites that were properly formed to pass infrared frequencies. Combining two layers of dendrites separated by a polymer film formed a capacitor-like configuration. This metamaterial could pass multiple bands of the infrared spectrum to some extent; in some cases, over 50 percent of the intensity was transmitted.

The amount of material made was even more impressive than its properties. Previous negative-index metamaterials were produced on the order of square micrometers—the new silver dendrite material was made in sheets of several hundred square millimeters.

The interaction of a flowing plasma with a dipole magnetic field: measurements and modelling of a diamagnetic cavity relevant to spacecraft protection.

Here we describe a new experiment to test the shielding concept of a dipole-like magnetic field and plasma, surrounding a spacecraft forming a 'mini magnetosphere'. Initial laboratory experiments have been conducted to determine the effectiveness of a magnetized plasma barrier to be able to expel an impacting, low beta, supersonic flowing energetic plasma representing the solar wind. Optical and Langmuir probe data of the plasma density, the plasma flow velocity and the intensity of the dipole field clearly show the creation of a narrow transport barrier region and diamagnetic cavity virtually devoid of energetic plasma particles. This demonstrates the potential viability of being able to create a small 'hole' in a solar wind plasma, of the order of the ion Larmor orbit width, in which an inhabited spacecraft could reside in relative safety. The experimental results have been quantitatively compared with a 3D particle-in-cell 'hybrid' code simulation that uses kinetic ions and fluid electrons, showing good qualitative agreement and excellent quantitative agreement. Together the results demonstrate the pivotal role of particle kinetics in determining generic plasma transport barriers.

Researchers at the Science and Technology Facilities Council's Rutherford Appleton Laboratory, the Universities of York, Strathclyde and IST Lisbon, have undertaken experiments, using know-how from 50 years of research into nuclear fusion, to show that it is possible for astronauts to shield their spacecrafts with a portable magnetosphere - scattering the highly charged, ionised particles of the solar wind and flares away from their space craft.

Computer simulations done by a team in Lisbon with scientists at Rutherford Appleton last year showed that theoretically a very much smaller "magnetic bubble" of only several hundred meters across would be enough to protect a spacecraft.

Now this has been confirmed in the laboratory in the UK using apparatus originally built to work on fusion. By recreating in miniature a tiny piece of the Solar Wind, scientists working in the laboratory were able to confirm that a small "hole" in the Solar Wind is all that would be needed to keep the astronauts safe on their journey to our nearest neighbours.

Dr. Ruth Bamford, one of the lead researchers at the Rutherford Appleton Laboratory, said, "These initial experiments have shown promise and that it may be possible to shield astronauts from deadly space weather".

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