Potential Applications of Concentrated Solar Energy Proceedings of a Workshop (1991) / Chapter Skim
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3 SESSION 3 - MATERIALS PROCESSING AND SYNTHESIS
3 SESSION 3 - MATERIALS PROCESSING AND SYNTHESIS
Pages 59-96
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From page 59... ...
Thus, in Session 3, Materials Processing and Synthesis, the technology area judged to be most amenable to application of concentrated solar photons wan surface treatment and modification. The first two speakers in Session 3 addressed this area, with descriptions of current surface modification and thin film growth technologies.
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From page 60... ...
Surface Heating Way Lid Since visible light i" absorbed in about the first 30 nm in most metal" and opaque materials, intense light fluxes can be used to selectively heat the surface region. Techniques which use light to heat surfaces can be classified according to the interaction time and energy density.
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From page 61... ...
Thus highly concentrated solar beams are ideally suited for surface heating. Solar furnaces can obtain concentration factors of up to 10,000 resulting in fluxes of 1000 W/cm2.
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From page 62... ...
However, CO2 lasers are even more energy inefficient than arc lamps, and thus solar furnaces have an even greater advantage. They can also deliver high power over larger areas and have better absorption characteristics than CO2 laser light.
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From page 63... ...
63 Also needed is more detailed economic analysis on "pecif ic applications to assess the practicality of the substantial investment required to fabricate a solar furnace .
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From page 64... ...
that rely on thermal processes (primarily diffusion) to produce the desired property in near-=urface regions, to Surface coating processes (e.g., electro- and electroless chemical deposition, chemical vapor deposition [CVD]
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From page 65... ...
Figures 1A and 1B show the effect of putter-cleaning on the adhesive strength of Ag films deposited on alumina and zirconia substrates, respectively[1,6]
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From page 66... ...
to chemically assist the formation of volatile compounds from the surface contaminants. Concentrated solar beams could also be used to deposit films.
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From page 67... ...
Concentrated solar beams "how potential as a viable energy source for a number of coating processes based on pyrolytic and photolytic reactions.
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From page 68... ...
1989. Interface Structure and Thin Film Adhesion.
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From page 69... ...
~ 3000 4000 5000 Time (s) FIGURE 1 Adhesive ~trength of silver films deposited on (A)
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From page 70... ...
For metallization of the pen junctions, the excimer laser beam" can also be used to deposit stoichiometric good quality TiN thin films by evaporation of bulk TiN targets. bat-Shear Pulsed excimer laser beams (wavelength ~ = 0.193-308 ~m, pulse duration = 15-45 x 10-9 see)
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From page 71... ...
To verify the working of the heat flow program the simulated values of the maximum melt depths were compared with the experimental values obtained by excimer laser irradiation of ion-implanted samples at various energy densities. Figure 1A shown TEM micrographs of boron-implanted samples which were irradiated with XeCl laser having a trapezoidal pulse shape and full width at half maximum (FWHM)
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From page 72... ...
The maximum melt depths for excimer XeC1 laser irradiation of silicon at different energy densities and pulse durations is shown in Figure 1B. For both 25 and 50 ns laser pulses, the maximum melt depth is found to be proportional to the energy density.
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From page 73... ...
The excimer laser can be used effectively for the metallization of the solar cell by depositing thin layers of TiN using the pulsed laser evaporation technique (PLE)
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From page 74... ...
74 result in large minority carrier lifet~mes. The excimer laser can be further used to evaporate stoichiometric nitride layer~ for metallization of the solar celln.
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From page 75... ...
3 FIGURE 1B Calculated depth of melting as a function of energy density and pulse duration for XeC1 laser irradiated Si samples. Reprinted with Permission from: Materials Sciences & Engineering Department, North Carolina State University
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From page 76... ...
seconds FIGURE 2A Melt from for 25 and 50 ns laser pul~e. Reprinted with Permission from: Materials Sciences & Engineering Department, North Carolina State University 2700 2300 900 ~D a, c~ 1500 1 100 ~T I T -- I T -1 r- - 1 ~1 Energy density A=308 nm 25 ~cm' T = 25 ns 2 0 ~c~2 -- - 1 5 J/=n2 ......
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From page 77... ...
30Q 400 500 600 700 800 900 ~O ] 100 Wavelengt h nanometer FIGURE 3B Comparison of the internal quantum efficiency between cells fabricated using excimer laser annealing after BF3+ (lkV)
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From page 78... ...
Kr - Tic ~y ~ FIGURE 4B Auger electron spectrum taken from a bulk TiN target irradiated after 4 min Ar sputtering. Reprinted with Permission from: Materials Sciences & Engineering Department, North Carolina State University
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From page 79... ...
New directions in coating technology using highly concentrated solar beams to induce chemical vapor deposition processes are described here. Application areas that have not been researched in detail but would appear to be good matches to the solar technology are also reviewed.
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From page 80... ...
. We have looked at perfo,..`ing surface modification processes with highly concentrated solar beams in Rome detail.
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From page 81... ...
When powders of starting materials or layer" of thin films are used, it i" sometimes found that the reactions do not propagate uniformly. Further, for some materials the reactions can only be sustained or the right product can be obtained only if the reaction mixture is maintained above a defined (high)
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From page 82... ...
A high-vacuum-compatible target chamber was constructed to allow this. By modifying the chamber to allow us to control the flow of reactive gases over the target during exposure to the solar beam, we produced the capability of conducting rapid thermal chemical vapor deposition that results in thin film growth directly on the target.
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From page 83... ...
1990. A Comparison of the Economics of Materials Processing with Solar Furnaces and High-Intensity Arc Lamp-.
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From page 84... ...
Kolb Sandia National Laboratories Albuquerque, New Mexico Absb~ The cost and performance of treating materials with a solar furnace were compared to similar treatment with high-intensity electric-arc lamp=. Qualitative results indicate that because of the long focal length of the solar furnace, it is capable of performing much dirtier materials processing tasks than the arc lamp.
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From page 85... ...
A typical Vortek arc lamp system i" pictured in Figure 1. Des~p~n of the So - Furnace Sin Many experimental solar furnaces exist throughout the world.
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From page 86... ...
iThin is a conservative assumption since certain materials processing tasks may be able to use variable power levels and flux shapes. 2In a poor solar region the arc lamp would also beat the furnace because capital equipment located in the assembly line would be underutilized.
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From page 87... ...
The annual energy is the summation of the optical power delivered to the target over the course of a year and is expressed in kilowatt-hour. In Table 1 and 2 we compare estimates for installed capital costs, O&M costs, annual energy, and LEC for the arc lamps and solar furnace for a batch mode operation in which they are operated 6 hours per day.
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From page 88... ...
· Because of better utilization of the operating crew, the arc lamp is recommended for materials processing tasks located within a continuous process . · The capital cost of an arc lamp is lower than that of a molar furnace.
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From page 89... ...
In closing, it should be noted that for applications requiring significant exposure times at very high concentrations ( |
From page 90... ...
1988. Solar Central Receiver Technology Advancement for Electric Utility Applications, Phase 1 Topical Report, Report No 007 .
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From page 91... ...
Electricity Water Lamp replacement Reflector replacement Argon gas Anode replacement Cathode replacement General maintenance Total O&M cost Annual performance Annual operating hour" Power to target (kW) Annual energy to target (kWh)
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From page 92... ...
Annual energy to target ( S /kWh ) 83, 000 2,190 38 Levelized energy cost (S/kWh)
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From page 93... ...
~ .. ~ : Reprinted with Permission from: Sandia National Laboratories
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From page 94... ...
Reprinted with Permission from: Sandia National Laboratories ..
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From page 95... ...
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From page 96... ...
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