Darren M. King

University of Illinois, Urbana-Champaign | UIUC · Department of Aerospace Engineering

The capability of extending lean operational limits of methane-air flames has been demonstrated using the combination of annular swirled flow and plasma power deposition. The inclusion of plasma power deposition to the flame region initiates rapid decomposition of flow constituents driven by electron-impact processes as well as interactions with el...

CU Aerospace recently completed an Air Force Phase I SBIR to test a proof-of-principle Monopropellant Propulsion Unit for CubeSats (MPUC), consisting of a thrust chamber and demonstrating complete catalyzed combustion of an H2O2-based propellant denoted as CMP-8. CMP-8 has zero toxicity and no special measures are required for its long-term storage...

The atmospheric coaxial direct-coupled microwave torch configuration offers a convenient experimental format for validating multiphysics simulations of plasma-assisted combustion (PAC). The optical accessibility of this configuration allows for the application of various diagnostics to the PAC flame such as planar laser-induced fluorescence (PLIF)...

The CU Aerospace/VACCO Industries Propulsion Unit for CubeSats (PUC) was developed as a medium thrust, medium impulse thruster system to enable CubeSat orbital maneuvering, formation flying, and rendezvous. The 0.25U PUC casing is all-welded titanium, a n d comes fully integrated with all necessary propulsion subsystems, including controller, power...

High-temperature stable aromatic thermosetting copolyesters (ATSP) show great promise for use as a matrix in high-strength carbon fiber (C) composites. In this article, we characterize the ablation characteristics of ATSP/C composites using a high-power laser. ATSP/C shows very low recession rates of less than 0.14 mm/s at heat fluxes of approximat...

Continuing experiments with electric oxygen-iodine laser (ElectricOIL) technology have significantly increased laser power output by increasing the product of gain and gain-length, $g_{0}L$. The authors report on progress with recent ElectricOIL devices utilizing a new concentric discharge geometry with improved ${\rm O}_{2}(a^{1}\Delta)$ productio...

The authors report the development of an electric oxygen-iodine laser with higher output using a larger product of gain and gain length, g0L. A factor of 4.4 increase in laser power output on the 1315 nm atomic iodine transition was achieved with a factor of 3 increase in gain length. I(2P1/2) is pumped using energy transferred from O2(a1Δ) produce...

We present quantitative analysis of image sequences of multi-stream injection nozzle flows with several different injection geometries in an experiment simulating mixing in a chemical oxygen-iodine laser. To visualize mixing, image sequences were acquired with planar laser-induced fluorescence (PLIF) in iodine that was injected into the main flow....

A variant of an ejector-mixing nozzle for a chemical oxygen–iodine laser was experimentally tested with notched starlet ejectors. Cold-flow planar laser-induced fluorescence measurements indicated that the starlets provide faster mixing. Hot-flow testing demonstrated that the starlet design improved laser performance by 20–30% above the basic cylin...

A variant of an ejector mixing nozzle for a chemical oxygen-iodine laser (COIL) was experimentally tested with notched "starlet" ejectors. Cold flow planar laser induced fluorescence (PLIF) measurements indicate that the starlets provide faster mixing. Hot flow testing demonstrated that the starlet design improved laser performance by 20-30% above...

The mechanisms of the mixing between separate flows are of high interest in order to increase the efficiency of processes that rely on well mixed flows. Mixing of three flows was examined, where two of the flows were in an underexpanded state, and the third near-ideally expanded. One of the underexpanded flows served as a driver gas for the mixing...

The mechanisms of the mixing between separate flows are of high interest in order to increase the efficiency of processes that rely on well mixed flows, such as combustion. In this paper, Planar Laser Induced Fluorescence (PLIF), in two perpendicular planes, of an Iodine-seeded flow was used to visualize and quantify the mixing of three flows due t...

Laser action at 1315 nm on the I( 2 P1/2) → I( 2 P3/2) transition of atomic iodine has been obtained by a near resonant energy transfer from O2(a 1 ∆) produced using a low-pressure electric discharge. In the electric discharge oxygen-iodine laser (ElectricOIL) the discharge production of atomic oxygen, ozone, and other excited species adds signific...

Recent experiments have led to improvements in the hybrid Electric Oxygen-Iodine Laser (ElectricOIL) system that significantly increased the discharge performance, supersonic cavity gain, and laser power output. The continuous wave laser operating on the I( 2 P 1/2 ) → I( 2 P 3/2 ) transition of atomic iodine at 1315 nm was pumped by the production...

In the hybrid electric discharge Oxygen-Iodine laser (ElectricOIL), the desired O2(a1Δ) is produced using a low-to-medium pressure electric discharge. The discharge production of atomic oxygen, ozone, and other excited species adds higher levels of complexity to the post-discharge kinetics which are not encountered in a classic purely chemical O2(a...

Recent experiments have led to improvements in the hybrid Electric Oxygen-Iodine Laser (ElectricOIL) system that significantly increased the discharge performance, supersonic cavity gain, and laser power output. The continuous wave laser operating on the I(2P1/2) → I(2P3/2) transition of atomic iodine at 1315 nm was pumped by the production of O2(a...

Herein the authors report on the demonstration of a continuous-wave laser in subsonic flow on the 1315 nm transition of atomic iodine using the energy transferred to I() from O2(a ) produced by a radio-frequency-excited electric discharge. The electric discharge was sustained in an O2–He–NO gas mixture. Downstream of the discharge, cold gas injecti...

Recent experiments have led to improvements in the hybrid Electric Oxygen-Iodine Laser (ElectricOIL) system that significantly increased the laser power output. The continuous wave laser operating on the I(2P 1/2) → I(2P3/2) transition of atomic iodine at 1315 nm was pumped by the production of O2(a 1Δ) in a radio-frequency discharge in a He/O2 mix...

In this paper we report on studies of a continuous wave laser at 1315 nm on the I( 2 P 1/2 ) → I( 2 P 3/2 ) transition of atomic iodine where the O 2 (a 1 Δ) used to pump the iodine was produced by a radio frequency excited electric discharge. The electric discharge was sustained in He/O 2 gas mixtures upstream of a supersonic cavity which is emplo...

In this paper we report on studies of a continuous wave laser at 1315 nm on the I( 2 P 1/2 ) → I( 2 P 3/2 ) transition of atomic iodine where the O 2 (a 1 Δ) used to pump the iodine was produced by a radio frequency excited electric discharge. The electric discharge was sustained in He/O 2 and Ar/O 2 gas mixtures upstream of a supersonic cavity whi...

Laser action at 1315 nm on the I (²P_1/2)→ I (²P_3/2) transition of atomic iodine is conventionally obtained by a near-resonant energy transfer from O ₂(a¹Δ) which is produced using wet-solution chemistry. The difficulties in chemically producing O ₂(a¹Δ) has moti...

Laser action at 1315 nm on the I(²P₁2/)→I(²P₃2/) transition of atomic iodine is conventionally obtained by a near-resonant energy transfer from O₂(a¹Δ) which is produced using wet-solution chemistry. The system difficulties of chemically producing O₂(a¹Δ) have m...

Laser action at 1315 nm on the I(²P_1/2)→I(²P_3/2) transition of atomic iodine is conventionally obtained by a near-resonant energy transfer from O ₂(a¹Δ) , which is produced using wet-solution chemistry. The system difficulties of chemically producing O ₂(a¹Δ) ha...

Preliminary measurements of the yield of O 2 (1 Δ) as a function of power absorbed in an RF discharge are presented. The yield is deduced from measurements of gain/absorption using the PSI Iodine Scan diagnostic coupled with a data reduction technique originally developed by PSI. A more formal presentation of the method of deducing the yield is pro...

As the development of the electric discharge iodine laser continues, the role of oxygen atoms downstream of the discharge region was found to be very significant. One of the largest uncertainties is the rate of quenching of I* by O atoms. We have taken a series of measurements of O 2 ( 1 Δ) emission, I* emission, O-atom titrations, gain/absorption,...

Theoretical studies have indicated that sufficient fractions of O₂(¹Δ) may be produced in an electrical discharge that will permit lasing of an electric discharge oxygen-iodine laser (ElectriCOIL) system. Results of those studies along with more recent experimental results show that electric excitation is a very complicated pr...

Theoretical and experimental studies haveindicated that fractions of O2(1Δ) can be produced in anelectrical discharge that may permit lasing of an electricdischarge oxygen-iodine laser (ElectriCOIL) system,possibly in conjunction with the injection of predissociatediodine. Results of those studies along withmore recent experimental results show tha...

Theoretical studies have indicated that fractions of O 2 (1 D) can be produced in an electrical discharge that may permit lasing of an electric discharge oxygen-iodine laser (ElectriCOIL) system, possibly in conjunction with the injection of pre-dissociated iodine. In this paper, recent computations in the ElectriCOIL system are presented, includin...

Detailed studies of mechanisms for producing electrically initiated COIL lasers were previously presented. Results of those studies along with more recent experimental results show that electric excitation is a very complex process that must be investigated with advanced diagnostics. Theoretical studies indicate that fractions of O2( 1 Δ) may be pr...

Theoretical studies have indicated that sufficient fractions of O 2 (1 D) may be produced in an electrical discharge that will permit lasing of an electric discharge oxygen-iodine laser (ElectriCOIL) system in conjunction with injection of pre-dissociated iodine. Results of those studies along with more recent experimental results show that electri...

A chemical oxygen-iodine laser (COIL), the VertiCOIL device, was transferred from the Air Force Research Laboratory (AFRL) to the University of Illinois at Urbana-Champaign (UIUC) and made operational. The performance of the high-power VertiCOIL laser was measured with nitrogen diluent, New nozzle designs were investigated and implemented to optimi...

The chemical oxygen-iodine laser (COIL) is a high power, fiber deliverable tool, which can be used for a number of different industrial applications. COIL is of particular interest because of its short fiber deliverable wavelength, high scaleable continuous wave power, and excellent material interaction properties. In past research the University o...

Engineers at CU Aerospace (CUA) and The University of Illinois at Champaign-Urbana (UIUC) have developed an innovation to the classical chemical oxygen-iodine laser (COIL) singlet oxygen generator (SOG) based on discharge excitation of molecular oxygen. A number density of ~2.1x10 15 of O2( 1 Σ) was measured for a total O2 flow rate of 7 mmol/s and...

This paper investigates advanced mixing nozzle concepts for the chemical oxygen-iodine laser (COIL) that will significantly improve the chemical efficiency of such systems. It is believed that innovative nozzle design improvements should increase COIL chemical efficiencies. This technology will logically include injection of atomic rather than mole...

The chemical oxygen-iodine laser (COIL) is a high power, fiber deliverable tool, which can be used for a number of different industrial applications. Commercialization issues are discussed along with potential markets. Technological development efforts are underway to make this device usable for long run times and economically viable. New nozzle in...

In this paper, we report on studies of a continuous-wave laser at 1315 nm on the I(2 P 1 2) I(2 P 3 2) transition of atomic iodine where the O 2 (1 1) used to pump the iodine was produced by a radio frequency excited electric discharge. The electric discharge was sustained in He–O 2 and Ar–O 2 gas mix-tures upstream of a supersonic cavity which is...

The VertiCOIL device was transferred from the Air Force Research Laboratory (AFRL) to the University of Illinois at Urbana-Champaign (UIUC) and made operational. The performance of the high power VertiCOIL laser was measured with nitrogen diluent. New nozzle designs were investigated and implemented to optimize nitrogen performance. Nitrogen diluen...