Reed J. Jensen

Isotopic enrichment of SF6 in S34 by multiple absorption of CO2 laser radiation

An increase in the ratio of S34/S32 of 3300% over its natural ratio has been obtained by irradiating SF6 in the presence of H2 with an intensely focused CO2 laser. The quantities of material separated are on the order of 100 μg.

Laser induced dissociation of N2F4

Abstract A pulsed CO2 laser has been used to drive the dissociation of N2F4 by depositing energy directly in the vibrational degrees of freedom. It is observed that dissociation proceeds at an initial rate that far exceeds the measured thermal rate.

The ultraviolet absorption spectrum of hot carbon dioxide

Abstract The vacuum ultraviolet absorption spectrum of CO 2 shifts significantly to longer wavelengths with increasing temperature. We have measured this temperature dependence and present absorption cross sections for 230 to 355 nm at temperatures from 1523 to 2273 K. At 2273 K this red shift extends the absorption above 300 nm and well into the blue end of the solar spectrum. In CO 2 the thermal shift is enhanced because of the relative position and shapes of the excited and ground state potential curves.

Electric discharge initiated SF6 - H2 and SF6 - HBr chemical lasers

Abstract Hydrogen fluoride laser transitions were produced by electric discharge initiation of SF6 + HBr and SF6 + H2 mixtures. The reaction of H atom with SFX (X ⩽ 6) species is invoked to explain the P4(7) line observed in the reaction between SF6 and H2.

Chemical reactions occurring during direct solar reduction of CO2

At high temperatures carbon dioxide may absorb solar radiation and react to form carbon monoxide and molecular oxygen. The CO, so produced, may be converted by well-established means to a combustible fuel, such as methanol. We intend to make a future demonstration of the solar reduction of CO2 based on these processes. This paper, however, addresses only the problem of preserving, or even enhancing, the initial photolytic CO by quenching the hot gas with colder H2O or CO2. We present model calculations with a reaction mechanism used extensively in other calculations. If a CO2 gas stream is heated and photolyzed by intense solar radiation and then allowed to cool slowly, it will react back to the initial CO2 by a series of elementary chemical reactions. The back reaction to CO2 can be terminated with the rapid addition of CO2, water, or a mixture. Calculations show that a three-fold quench with pure CO2 will stop the reactions and preserve over 90% of the initial photolytic CO. We find that water has one of two effects. It can either increase the CO level, or it can catalyze the recombination of O and CO to CO2. The gas temperature is the determining factor. If the quench gas is not sufficient to keep the temperature below approximately 1100 K, a chain-branching reaction dominates and the reaction to CO2 occurs. If the temperature stays below that level a chain terminating reaction dominates and the CO is increased. The former case occurs below approximately a fourfold quench with a water/CO2 mixture. The later case occurs when the quench is greater than fourfold. We conclude that CO2, H2O, or a mixture may quench the hot gas stream photolyzed by solar radiation and preserve the photolytic CO.

Aluminum fluoride exploding‐wire laser

Intense aluminum fluoride laser pulses in the spectral range 12.5–13.5 μ were observed when fine aluminum wires were exploded into fluorine gas. The laser oscillation occurred during the expansion phase of the wire explosion.

Thermally initiated HF chemical laser

The ClN3 explosion has been used to thermally decompose NF3 and SF6 into fluorine atoms which react with H2 producing HF laser action. The reaction of H atom on fluorine bearing species is indicated by 4→3 HF laser transitions.

A traveling wave approach to plasma pumping for X-ray sources

Progress in high-brightness excimer lasers and in optical angular multiplexing of excimer lasers presents an opportunity to provide very intense pumping of X-ray sources, both in favorable geometry and in traveling waves, all at low cost. The traveling-wave strategy can be tailored to the parameters of the system to be pumped. This design option can be of great importance for systems lasing at wavelengths in the kilovolt regime where upper level lifetimes are short, and where mirror technology is presently tenuous. Features of several design strategies are explored.

Large Excimer Lasers For Fusion

Important goals in DOE and DoD programs require multimegajoule laser pulses. For inertial confinement fusion there is also a requirement to deliver the pulse in about 25 nsec with a very particular power vs time profile-all at high overall efficiency and low cost per joule. After exhaustive consideration of various alternatives, our studies have shown that the most cost effective approach to energy scaling is to increase the size of the final amplifiers up to the 200 to 300 Id level. This conclusion derives largely from the fact that, at a given complexity, costs increase slowly with increasing part size while output energy should increase dramatically. Extrapolations to low cost by drastic cuts in the unit cost of smaller devices through mass production are considered highly risky. At a minimum the requirement to provide, space, optics and mounts for such systems will remain expensive.