5 research outputs found
Solar silicon via the Dow Corning process
Technical feasibility for high volume production of solar cell-grade silicon is investigated. The process consists of producing silicon from pure raw materials via the carbothermic reduction of quartz. This silicon was then purified to solar grade by impurity segregation during Czochralski crystal growth. Commercially available raw materials were used to produce 100 kg quantities of silicon during 60 hour periods in a direct arc reactor. This silicon produced single crystalline ingot, during a second Czochralski pull, that was fabricated into solar cells having efficiencies ranging from 8.2 percent to greater than 14 percent. An energy analysis of the entire process indicated a 5 month payback time
Solar silicon via the Dow Corning process
Carbon, as a reductant for quartz, must be made available so as to have suitable reactivity in conjunction with high purity, especially with respect to boron and phosphorus. A detailed experimental plan was developed to do this. Different sources of carbon were selected to be subjected to various purification methods and reactivity-enhancement processes. A developmental scale arc furnace was installed to perform quartz-carbon reactivity testing
The Chandra Multiwavelength Project: Optical Followup of Serendipitous Chandra Sources
We present followup optical g', r', and i', imaging and spectroscopy of
serendipitous X-ray sources detected in 6 archival Chandra, images included in
the Chandra, Multiwavelength Project (ChaMP). Of the 486 X-ray sources detected
between 3e-16 and 2e-13 (with a median flux of 3e-15 erg cm-2 s-1, we find
optical counterparts for 377 (78%), or 335 (68%) counting only unique
counterparts. We present spectroscopic classifications for 125 objects,
representing 75% of sources with r<21 optical counterparts (63% to r=22). Of
all classified objects, 63 (50%) are broad line AGN, which tend to be blue in
g-r colors. X-ray information efficiently segregates these quasars from stars,
which otherwise strongly overlap in these SDSS colors until z>3.5. We identify
28 sources (22%) as galaxies that show narrow emission lines, while 22 (18%)
are absorption line galaxies. Eight galaxies lacking broad line emission have
X-ray luminosities that require they host an AGN (logL_X>43). Half of these
have hard X-ray emission suggesting that high gas columns obscure both the
X-ray continuum and the broad emission line regions. We find objects in our
sample that show signs of X-ray or optical absorption, or both, but with no
strong evidence that these properties are coupled. ChaMP's deep X-ray and
optical imaging enable multiband selection of small and/or high-redshift groups
and clusters. In these 6 fields we have discovered 3 new clusters of galaxies,
two with z>0.4, and one with photometric evidence that it is at a similar
redshift.Comment: 38 pages, Latex, emulateapj style, including 6 tables and 22 figures.
Accepted Aug 24, 2003 for publication in ApJ Supplement. See accompanying
X-ray papers by Kim et al. 2003 and the ChaMP web site at
http://hea-www.harvard.edu/CHAMP
Solar silicon via the Dow Corning process : final report /
" ... This work was performed for the Jet Propulsion Laboratory, California Institute of Technology by agreement between NASA and DOE.""JPL Contract No. 954559.""October 1979."Includes bibliographical references (pages 89-90).Work performed under contract no.Mode of access: Internet