Gerald C. Manke

A new energy transfer chemical laser at 1.315 μm

Abstract : CW laser action has been demonstrated on the electronic I(*) - I transition of atomic iodine at 1.315 microns from the NCL(a) + I energy transfer reaction. The stimulated emission was generated in a transverse subsonic flow device when hydrogen azide, HN3, was injected into a flow of iodine and chlorine atoms. The measured laser output power was 180 mW.

The Measurement of Gain on the 1.315 Micrometers Transition of Atomic Iodine in a Subsonic Flow of Chemically Generated NCl(a(1) delta)

Abstract Gain is measured on the electronic I( 2 P 3/2 )– I ∗ ( 2 P 1/2 ) transition of atomic iodine at 1.315 μm when hydrazoic acid HN 3 is injected into a flow of iodine and chlorine atoms. The inversion was generated in a transverse subsonic flow device that produced electronically excited I ∗ ( 2 P 1/2 ) atoms from the efficient energy transfer reaction between NCl(a 1 Δ ) metastable and ground state I ( 2 P 3/2 ) atoms. The population inversion was directly observed using a 1.315 μm tunable diode laser that scanned the entire line shape of the (3,4) hyperfine transition of iodine.

Characterizing Fluorine and Chlorine Atom Flow Rates Using Iodine Atom Spectrometry

The production of F and Cl atoms in an electrical discharge of F 2 or Cl 2 has been examined in a flow reactor. A tunable diode laser was used to probe the concentration and translational temperature of I atoms produced by F and Cl atom reactions with HI. Kinetic modeling codes were used to determine the discharge efficiencies from the titration plots and the observed trends for atom concentration as a function of F 2 or Cl 2 and pressure. These calculations indicate that the de discharge used in these experiments is 100% efficient for F 2 flow rates ≤0.5 mmol s -1 and reactor pressure ≤20 torr. The highest F 2 -free F atom flow rate that we can generate is 1.0 mmol s -1 . Preliminary data for the Cl 2 discharge indicate that this is a much less efficient source of Cl atoms with yields of less than 50%.

Advanced COIL--physics, chemistry and uses

A review of Chemical Oxygen Iodine Laser (COIL) chemistry, physics, and technology is presented. Individual COIL components are discussed in relation to the COIL heuristic equation, which predicts COIL performance based on well-known, measurable, device performance parameters. Topics include singlet oxygen generators (SOGs), supersonic nozzle designs, I 2 mixing, and I 2 dissociation. In addition, a brief summary of the recently invented All Gas-phase Iodine Laser (AGIL) is given, where the I*(2P½) → I(2P3/2) inversion was generated by the NCl(a1 δ) + I(2P 3/2) energy transfer reaction.

A multiwatt all gas-phase iodine laser (AGIL)

The demonstration and characterization of a multiwatt All Gas-phase Iodine Laser (AGIL) are described. A 20-cm subsonic reactor was used to produce NCl(a1Δ) for a series parametric studies of the I*(2P1/2) - I(2P3/2) small signal gain and extracted power dependence on reactant flow rates and reaction time. A reduction in the flow channel height led to improved performance. The highest measured gain was 4.2 x 10-4 cm-1 and the highest power observed was 31 W.

Tunable diode laser gain measurements on the HF(2-0) overtone transistions in a small-scale HF laser

A tunable diode laser was used to probe the overtone gain medium of a small-scale HF laser. Two-dimensional, spatially resolved small signal gain and temperature maps were generated for the P(3) ro-vibrational transition in the first HF overtone band.

Non-Intrusive mach number measurement in a supersonic hydrogen fluoride laser

An experimental technique has been developed to directly measure flow velocity and Mach number in a supersonic hydrogen fluoride laser. The technique uses a tunable diode laser source to probe the laser cavity at an angle to the flow creating a Doppler shifted lineshape. The amount of Doppler shift can be related to the flow velocity. The diode laser was traversed in the vertical direction to produce velocity and Mach number profiles.

Recent Progress in the Development of a Multi-Watt All Gas-Phase Iodine Laser (AGIL)

Recent results in the development of a multi-watt All Gas-phase Iodine Laser (AGIL) are presented. A description of the subsonic hardware used to produce NCl(a 1 Δ), direct measurements of I*( 2 P1/2) - I( 2 P3/2) small signal gain, and parametric studies to optimize the gain are described.

Kinetic spectroscopy of NCl

Metastable NCl(a1(Delta) ) is a promising energy carrier for use in chemically driven iodine lasers. The present studies of NCl(a) kinetics and demonstration of a non- intrusive method for detecting NCl(X) were conducted in support of efforts to develop an NCl(a)/I laser system. Photolysis of ClN3 by O2, H2, HCl, Cl2 and ClN3 were determined. The result were consistent with recent measurements made in a discharge flow system. NCl(X) was detected via transient absorption of the b-(chi) system. A CW ring dye laser was used to record a high-resolution spectrum of the origin band. Time resolved absorption measurements were used to examine the kinetics of NCl(X) formation and decay.

The Measurement of Gain in a Supersonic, Combustion-Driven Generator for NCl(a1Delta)

The measurement of positive small signal gain on the 1.315 micron spin orbit transition of atomic iodine following energy transfer from chemically generated NCl(a1Δ) is reported. Previous instances of gain produced by energy transfer from NCl(a1Δ) used DC discharges to generate F and Cl atoms; this report describes recent progress towards a true chemical laser device which uses a high temperature chemical combustor and a supersonic reactor to generate NCl(a1Δ). These improvements represent a significant step towards the development and demonstration of a scalable All Gas-phase Iodine Laser (AGIL) device.