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David L. Carroll

David L. Carroll
CU Aerospace · ---

Ph.D.

About

174
Publications
30,699
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2,847
Citations
Introduction
David L. Carroll is the President of CU Aerospace, and is a Visiting Professor at the University of Illinois at Urbana-Champaign. David does research in Electric Propulsion, High Energy Lasers, Plasmadynamics, Multiphysics Simulations, Optics, Quantum Physics and Computational Physics.
Additional affiliations
August 2011 - present
University of Illinois, Urbana-Champaign
Position
  • Professor

Publications

Publications (174)
Conference Paper
View Video Presentation: https://doi.org/10.2514/6.2022-1548.vid A plasma swirler, based on an existing Lorentz force driven gliding arcs, was developed as a flame holding and combustion enhancing device for premixed and diffusion flames. The device is intended to deliver the combined benefits of jet swirlers and plasma assisted combustion by provi...
Conference Paper
View Video Presentation: https://doi.org/10.2514/6.2022-2257.vid Magnetically-guided atmospheric arc devices were applied to provide plasma-excitation to premixed methane-air flames. Researchers have recently applied similar technology to study vortex generation for aerodynamic flow control, and the scaling and driver circuits used for those device...
Article
Full-text available
Parametric measurements of pulsed output energy from the four-level exciplex pumped alkali laser (XPAL) for Cs-Ar, Cs-Kr, and Cs-Xe as a function of input pump energy and temperature show a strong dependence on temperature. All three Cs-rare gas mixtures show a D2 line laser performance increase with temperature towards a peak efficiency, followed...
Conference Paper
Full-text available
A novel axisymmetric device with pulsed spark emission was developed as an active flow control alternative to passive vortex generators. The flowfield induced by the actuator was studied in quiescent flow. The current-voltage characteristics and power requirements of the high-voltage circuit that powered the discharge were detailed at different ope...
Article
Full-text available
A novel axisymmetric device with pulsed spark emission was developed as an active flow control alternative to passive vortex generators. The flowfield induced by the actuator was studied in quiescent flow. The current–voltage characteristics and power requirements of the high-voltage circuit that powered the discharge were detailed at different ope...
Article
Cs atomic lasers, operating on the D2 line and pumped by the photoassociation of Cs-rare gas thermal collision pairs, have been examined in mixtures of Cs vapor with Ar, Kr, or Xe. Photoexcitation of the B ²Σ⁺ − X ²Σ⁺ molecular transition (i.e., the blue satellite of the D2 transition) at 836.7 nm (Cs-Ar), 841.1 nm (Cs-Kr), or 842.7 nm (Cs-Xe) yiel...
Conference Paper
Full-text available
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...
Conference Paper
Full-text available
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...
Conference Paper
Full-text available
The CubeSat High Impulse Propulsion System (CHIPS), under development by CU Aerospace with partner VACCO Industries, is a system targeted at CubeSat and micro-satellite platforms designed to enable mission operations beyond simple orbit maintenance, including significant altitude changes, formation flying, and proximity operations such as rendezvou...
Conference Paper
Full-text available
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)...
Conference Paper
Full-text available
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...
Conference Paper
Full-text available
The increasingly successful use of nanosatellites has made CubeSat an attractive form factor for a number of missions that require both an attitude control system (ACS) and primary propulsion. The CubeSat High Impulse Propulsion System (CHIPS), under development by CU Aerospace with partner VACCO Industries, is designed to enable CubeSat mission op...
Article
Full-text available
Experiments[1] with Electric Oxygen-Iodine Laser (ElectricOIL) heat exchanger technology have demonstrated improved control of oxygen atom density and thermal energy, with minimal quenching of O2(a1Δ), and increasing small signal gain from 0.26% cm-1 to 0.30% cm-1. Heat exchanger technological improvements were achieved through both experimental an...
Article
Photoionization of Cs (6p 2P3/2) atoms during the operation of a Cs D2 line (852.1 nm: 6p 2P3/2→6s 2S1/2) laser, pumped by free→free transitions of thermal Cs-Ar ground state pairs, has been investigated experimentally and computationally. Photoexcitation of Cs vapor/Ar mixtures through the blue satellite of the D2 transition (peaking at 836.7 nm)...
Article
Full-text available
The exciplex pumped alkali laser (XPAL) system has been demonstrated in mixtures of Cs vapour, Ar, with and without ethane, by pumping Cs–Ar atomic collision pairs and subsequent dissociation of diatomic, electronically excited CsAr molecules (exciplexes or excimers). The blue satellites of the alkali D2 lines provide an advantageous pathway for op...
Conference Paper
Full-text available
Over the last decade new advanced gas lasers have emerged as possible candidates for high power laser systems that may supplant more conventional chemical and gas laser systems. Among these are the electric oxygen-iodine laser (ElectricOIL), the diode pumped alkali laser (DPAL), the exciplex pumped alkali laser (XPAL), and the optically pumped meta...
Article
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...
Article
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...
Article
Full-text available
Continuing experiments with Electric Oxygen-Iodine Laser (ElectricOIL) technology have significantly increased laser power output by increasing the product of gain and gain-length, g0L. The authors report on progress with recent ElectricOIL devices utilizing a new concentric discharge geometry with improved O2(a1▵) production at higher discharge op...
Article
The exciplex pumped alkali laser (XPAL) system has been demonstrated in mixtures of Cs vapor, Ar, with and without ethane, by pumping Cs-Ar atomic collision pairs and subsequent dissociation of diatomic, electronically-excited CsAr molecules (exciplexes or excimers). The blue satellites of the alkali D2 lines provide an advantageous pathway for opt...
Article
Full-text available
Continuing experiments with Electric Oxygen-Iodine Laser (EOIL) technology have significantly increased laser power output by increasing the product of gain and gain-length, g0L. Increasing the system size by a factor of 3 resulted in a 5-fold increase in laser output on the 1315-nm transition of atomic iodine. The peak output power observed was 53...
Article
The CubeSail mission is a low-cost demonstration of the UltraSail solar sailing concept (, , and ), using two near-identical CubeSat satellites to deploy a 260 m-long, 20 m2 reflecting film. The two satellites are launched as a unit, detumbled, and separated, with the film unwinding symmetrically from motorized reels. The conformity to the CubeSat...
Article
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....
Data
Full-text available
UltraSail is a next-generation high-payoff system with very large (kilometers-squared class) solar sails enabling high payload mass fractions for high Delta-V. One of the primary innovations is the near elimination of sail supporting structures by attaching each blade tip to a formation-flying tip satellite. To design the deployment of kilometers-l...
Article
Full-text available
The first high energy lasers were demonstrated in the mid-1960s and have made tremendous strides over the past 40+ years. This paper presents a sampling of the older work, some recent high energy laser technologies, and a discussion of what might come to be over the next 20 years.
Article
Full-text available
Several variants of an ejector mixing nozzle concept for a high-pressure chemical oxygen-iodine laser (COIL) have been experimentally tested. To obtain a better understanding of how much performance enhancement could be expected with increased mixing and to facilitate a larger parametric study we utilized the quasi-1D BLAZE-IV model to simulate the...
Article
The exciplex-pumped alkali laser (XPAL) system has been demonstrated in mixtures of Cs vapour, Ar, and ethane by pumping Cs–Ar atomic collision pairs and subsequent dissociation of diatomic, electronically excited CsAr molecules (exciplexes or excimers). Because of the addition of atomic collision pairs and exciplex states, modelling of the XPAL sy...
Article
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...
Article
Experiments and modelling have led to continued enhancements in the electric oxygen–iodine laser system. This continuous wave laser operating on the 1315 nm transition of atomic iodine is pumped by the production of O 2 (a) in a radio-frequency discharge in an O 2 /He/NO gas mixture. New discharge geometries have led to improvements in O 2 (a) prod...
Article
The exciplex pumped alkali laser (XPAL) system has been demonstrated in mixtures of Cs vapor, Ar, with and without ethane, by pumping Cs-Ar atomic collision pairs and subsequent dissociation of diatomic, electronically-excited CsAr molecules (exciplexes or excimers). The blue satellites of the alkali D2 lines provide an advantageous pathway for opt...
Article
Full-text available
Experiments and modeling have led to a continuing evolution of the Electric Oxygen-Iodine Laser (ElectricOIL) system. A new concentric discharge geometry has led to improvements in O2(a) production and efficiency and permits higher pressure operation of the discharge at high flow rate. A new heat exchanger design reduces the O2(a) loss and thereby...
Article
Full-text available
Lee H. Sentman III (1937-2010) contributed to many fields in aerospace sciences for nearly five decades before his passing. He pursued his passion for flight and aeronautics through education, science, teaching, and decades of flight experience. He specialized in non-equilibrium gas kinetic flows and was the first to demonstrate the importance of q...
Article
Full-text available
Solar sails can play a critical role in enabling solar and heliophysics missions. Solar sail technology within NASA is currently at 80% of TRL-6, suitable for an in-flight technology demonstration. It is conceivable that an initial demonstration could carry scientific payloads that, depending on the type of mission, are commensurate with the goals...
Article
Full-text available
Experiments and modeling have led to a continuing evolution of the Electric Oxygen-Iodine Laser (ElectricOIL) system. This continuous wave (cw) laser operating on the 1315 nm transition of atomic iodine is pumped by the production of O2(a) in a radio-frequency (RF) discharge in an O2/He/NO gas mixture. New discharge geometries have led to improveme...
Article
Full-text available
The exciplex pumped alkali laser (XPAL) system has been demonstrated in mixtures of Cs vapor, Ar, with and without ethane, by pumping Cs-Ar atomic collision pairs and subsequent dissociation of diatomic, electronically-excited CsAr molecules (exciplexes or excimers). The blue satellites of the alkali D2 lines provide an advantageous pathway for opt...
Article
Full-text available
Recent advances in the effort to demonstrate the propulsion capabilities of a microcavity discharge (MCD) thruster are discussed. The MCD thruster is being developed primarily through an experimental effort with support from computational modeling, and predicts an ultimate performance of 1 mN of thrust per cavity, a thrust efficiency exceeding 60%,...
Article
Lasing on the D2 (6p 2P3/2→6s 2S1/2) transition of atomic Cs at 852.1 nm has been observed with a four level system in which the Cs 6p 2P3/2 state is pumped by the photoassociation and subsequent dissociation of Cs-rare gas collision pairs. Characterized by a quantum efficiency >98%, this laser requires no atomic precursor to the upper laser level...
Article
Full-text available
The authors observed 95% enhancement in continuous-wave laser power on the 1315 nm transition of atomic iodine for only a 50% increase in gain length (5.1 cm to 7.6 cm), flow rates, and discharge input power, making use of a large volume 16-mm gap transverse discharge. A gain of 0.26% cm -1 was obtained and the laser output power was 55 W in a stab...
Article
Full-text available
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...
Article
Full-text available
Experiments and modeling have led to continued enhancements in the Electric Oxygen-Iodine Laser (ElectricOIL) system. This continuous wave (cw) laser operating on the 1315 nm transition of atomic iodine is pumped by the production of O 2 (a) in a radio-frequency (RF) discharge in an O 2 /He/NO gas mixture. New discharge geometries have led to impro...
Article
Full-text available
Experiments and modeling have led to continued enhancements in the Electric Oxygen-Iodine Laser (ElectricOIL) system. This continuous wave (cw) laser operating on the 1315 nm transition of atomic iodine is pumped by the production of O 2 (a) in a radio-frequency (RF) discharge in an O 2 /He/NO gas mixture. New discharge geometries and increases in...
Conference Paper
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...
Article
Herein the authors report on the demonstration of an 87% enhancement in cw laser power on the 1315 nm transition of atomic iodine via a 100% increase in the resonator mode volume. O(2)(a1Delta) is produced by a single rf-excited electric discharge sustained in an O(2)-He-NO gas mixture flowing through a rectangular geometry, and I(P2(1/2)) is then...
Article
Experiments and modeling have led to continued enhancements in the Electric Oxygen-Iodine Laser (ElectricOIL) system. This continuous wave (cw) laser operating on the 1315 nm transition of atomic iodine is pumped by the production of O2(a) in a radio-frequency (RF) discharge in an O2/He/NO gas mixture. New discharge geometries have led to improveme...