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Solar Power without Solar Cells
A dramatic and surprising magnetic effect of light discovered by University of Michigan1researchers could lead to solar power without traditional semiconductor-based solar cells.
The researchers found a way to make an optical 51 , said Stephen Rand, a professor in the departments of Electrical Engineering and Computer Science, Physics and Applied Physics.
Light has electric and magnetic 52 . Until now, scientists thought the effect of the magnetic field were so weak that they could be 53 . What Rand and his colleagues found is that at the right intensity, when light is traveling through a material that does not 54 electricity, the light field can generate magnetic effects that are 100 million times stronger than previously expected. Under these circumstances, the magnetic effects develop strength 55 to a strong electric effect.
This could lead to a new kind of solar cell without semiconductors and without absorption to produce charge separation, Rand said. In solar cells, the 56 goes into a material, gets absorbed and creates heat. Here, we expect to have a very low heat load2. Instead of the light being absorbed, energy is stored in the magnetic moment3. Intense magnetization can be induced by intense light and then it is ultimately capable of providing a capacitive power 57 What makes this possible is a previously undetected brand of optical rectification, says William Fisher, a doctoral student in applied physics. In traditional optical rectification, lights electric field causes a charge separation, or a pulling 58 of the positive and negative charges in a material. This sets up a voltage, similar to 59 in a battery.
Rand and Fisher found that under the right circumstances and in right types of materials, the lights magnetic field can also create optical rectification. The light must be shone through a 60 that does not conduct electricity, such as glass. And it must be focused to an intensity of 10 million watts per square centimeter8. Sunlight isnt this 61 on its own, but new materials are being sought that would work at lower intensities, Fisher said.
In our most recent paper, we show that incoherent light9 like sunlight is theoretically almost 62 effective in producing charge separation as laser light is, Fisher said.
This new 63 could make solar power cheaper, the researchers say. They predict that with improved materials they could achieve 10 percent efficiency in converting solar power to useable energy. Thats equivalent to todays commercial-grade solar cells.
To manufacture modem solar cells, you have to do 64 semiconductor processing, Fisher said. All we would need are lenses to focus the light and a fiber to guide it. Glass works for 65 .Its already made in bulk, and it doesnt require as much processing. Transparent ceramics might be even better.
51. A. disc B. fiber C. instrument D. battery
答案:D
52. A. applications B. components C. resources D. differences
答案:B
53. A. concerned B. ignored C. expected D. noticed
答案:B
54. A. conduct B. produce C. use D. consume
答案:A
55. A. reactive B. preferable C. due D. equivalent
答案:D
56. A. light B. electricity C. chemical D. gas
答案:A
57. A. plant B. source C. equipment D. line
答案:B
58. A. up B. down C. apart D. together
答案:C
59. A. this B. those C. that D. these
答案:C
60. A. material B. device C. detector D. meter
答案:A
61. A. bright B. faint C. visible D. intense
答案:D
62. A. more B. as C. much D. such
答案:B
63. A. skill B. technology C. miracle D. prototype
答案:B
64. A. extensive B. interactive C. selective D. intensive
答案:A
65. A. all B. some C. others D. both
答案:D
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