Solar ♦ news digest
capabilities of AF-M315E, a high-performance green alternative to hydrazine that has traditionally been used to fuel many spacecrafts.
This innovative, low-toxicity propellant is expected to improve overall vehicle performance. It boasts a higher density than hydrazine, meaning that more can be stored in containers of the same volume, and it delivers a greater thrust per given quantity of fuel.
GPIM is supported by co-investigators. These include NASA’s Glenn Research Centre and the U.S. Air Force Research Laboratory at Wright-Patterson Air Force Base in Ohio; Aerojet Corporation, a GenCorp company in Washington; NASA’s Kennedy Space Centre in Florida; and the U.S. Air Force Space & Missile Systems Centre at Kirtland Air Force Base in New Mexico.
“ATK is pleased to be providing the solar arrays for the GPIM project to Ball Aerospace, and we look forward to another successful collaboration with Emcore in support of this innovative program,” says Dave Messner, General Manager of ATK Space Systems in Goleta, California.
“Emcore is extremely pleased and honoured to receive this program award from ATK,” adds Brad Clevenger, General Manager of Emcore’s Photovoltaics Division. “Emcore has partnered with ATK on many successful missions, and we greatly value our long-standing business relationship. We look forward to supporting ATK on the Green Propellant Infusion Mission.”
Emcore is a manufacturer of highly-efficient radiation- hard solar cells for space power applications. With a Beginning-Of-Life (BOL) conversion efficiency nearing 30 percent and the option for a patented, onboard monolithic bypass diode, Emcore’s multi-junction solar cells provide amongst the highest available power to interplanetary spacecraft and earth orbiting satellites.
Solar cell interference reduced by moth eye reflection
Mimicking nature can improve thin-film III-V solar cells and other optoelectronic devices
Inspired by the structure of moth eyes, researchers at North Carolina State University have developed nanostructures that limit reflection at the interfaces where two thin films meet.
This suppresses the “thin-film interference” phenomenon commonly observed in nature which could potentially improve the efficiency of thin-film solar cells and other optoelectronic devices.
Thin-film interference occurs when a thin film of one substance lies on top of a second substance.
The phenomenon of interference and no interference are depicted in the schematic above.
For example, thin-film interference is what causes the rainbow sheen we see when there is gasoline in a puddle of water.
Gasoline is transparent, but some light is still reflected off of its surface. Similarly, some of the light that passes through the gasoline is reflected off the underlying surface of the water where the two substances interface, or meet.
Because the light reflected off the water has to pass back through the gasoline, it takes a slightly different optical path than the light that was reflected off the surface of the gasoline.
The mismatch of these optical path “lengths” is what creates the rainbow sheen - and that phenomenon is thin-film interference.
June 2013
www.compoundsemiconductor.net 141
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