Engineering topics

Coldwell, D. M.

Publications and source records attributed to Coldwell, D. M..

2 records

NASA NTRS1977

The reduction of SiO2 with carbon in a plasma

The feasibility of a process for the reduction of low impurity silica (SiO2) with carbon in a plasma heat source was investigated. An RF induction plasma reactor was fabricated and used to optimize process variables. Maximum silicon content of the product was 33% by weight. Emission spectrographic analysis of this product showed a reduction in some impurity levels of one to two orders of magnitude. While the plasma approach proved technically feasible, poor heat transfer from the plasma to the reactant and low yield make the process economically unattractive for large-scale use.

Coldwell, D. M.↗

NASA NTRS1977

Silicon material task. Part 3: Low-cost silicon solar array project

The feasibility of a process for carbon reduction of low impurity silica in a plasma heat source was investigated to produce low-cost solar-grade silicon. Theoretical aspects of the reaction chemistry were studied with the aid of a computer program using iterative free energy minimization. These calculations indicate a threshold temperature exists at 2400 K below which no silicon is formed. The computer simulation technique of molecular dynamics was used to study the quenching of product species.

Roques, R. A.↗