Engineering topics

McDanal, A. J.

Publications and source records attributed to McDanal, A. J..

11 records

NASA NTRS2018

Advanced Development of Space Photovoltaic Concentrators Using Robust Lenses, Multi-Junction Cells, and Graphene Radiators

At the past three PVSCs, our team has presented recent advances in our space photovoltaic concentrator technology. In the past year, under multiple NASA-funded research and technology development programs, our team has made much additional progress in the advanced development of space photovoltaic concentrators. New robust Fresnel lenses, new high-efficiency multi-junction cells, and new graphene radiators have been developed. The paper will present the latest advances in this technology.

O'Neill, Mark↗

NASA NTRS2016

Space Photovoltaic Concentrator Using Robust Fresnel Lenses, 4-Junction Cells, Graphene Radiators, and Articulating Receivers

At the 42nd PVSC, our team presented recent advances in our space photovoltaic concentrator technology. These advances include more robust Fresnel lenses for optical concentration, more thermally conductive graphene radiators for waste heat rejection, improved color-mixing lens technology to minimize chromatic aberration losses with 4-junction solar cells, and an articulating photovoltaic receiver enabling single-axis sun-tracking, while maintaining a sharp focal line despite large beta angles of incidence. In the past year, under a NASA Phase II SBIR program, our team has made much additional progress in the development of this new space photovoltaic concentrator technology, as described in this paper.

photovoltaic↗

NASA NTRS2015

Recent Space PV Concentrator Advances: More Robust, Lighter, and Easier to Track

Over the past three years, the authors have collaborated on several significant advances in space photovoltaic concentrator technology, including a far more robust Fresnel lens for sunlight concentration, improved color-mixing features for the lens to minimize chromatic aberration losses for next-generation 4-junction and 6-junction IMM cells, a new approach to suntracking requiring only one axis of rotation even in the presence of large beta angles (e.g., +/- 50 deg), a new waste heat radiator made of graphene, with 80-90% reduction in mass, and a new platform for deployment and support on orbit (SOLAROSA). These patent-pending advances are described in this paper.

concentrators↗

NASA NTRS2006

Stretched Lens Array (SLA) for Collection and Conversion of Infrared Laser Light: 45% Efficiency Demonstrated for Near-Term 800 W/kg Space Power System

For the past 2% years, our team has been developing a unique photovoltaic concentrator array for collection and conversion of infrared laser light. This laser-receiving array has evolved from the solar-receiving Stretched Lens Array (SLA). The laser-receiving version of SLA is being developed for space power applications when or where sunlight is not available (e.g., the eternally dark lunar polar craters). The laser-receiving SLA can efficiently collect and convert beamed laser power from orbiting spacecraft or other sources (e.g., solar-powered lasers on the permanently illuminated ridges of lunar polar craters). A dual-use version of SLA can produce power from sunlight during sunlit portions of the mission, and from beamed laser light during dark portions of the mission. SLA minimizes the cost and mass of photovoltaic cells by using gossamer-like Fresnel lenses to capture and focus incoming light (solar or laser) by a factor of 8.5X, thereby providing a cost-effective, ultra-light space power system.

O'Neill, Mark↗

NASA NTRS2005

Recent Progress on the Stretched Lens Array (SLA)

At the last Space Photovoltaic Research and Technology Conference, SPRAT XVII, held during the fateful week of 9/11/01, our team presented a paper on the early developments related to the new Stretched Lens Array (SLA), including its evolution from the successful SCARLET array on the NASA/JPL Deep Space 1 spacecraft. Within the past two years, the SLA team has made significant progress in the SLA technology, including the successful fabrication and testing of a complete four-panel prototype solar array wing (Fig. 1). The prototype wing verified the mechanical and structural design of the rigid-panel SLA approach, including multiple successful demonstrations of automatic wing deployment. One panel in the prototype wing included four fully functional photovoltaic receivers, employing triple-junction solar cells.

O'Neill, Markl↗

NASA NTRS2005

Promising Results from Three NASA SBIR Solar Array Technology Development Programs

Results from three NASA SBIR solar array technology programs are presented. The programs discussed are: 1) Thin Film Photovoltaic UltraFlex Solar Array; 2) Low Cost/Mass Electrostatically Clean Solar Array (ESCA); and 3) Stretched Lens Array SquareRigger (SLASR). The purpose of the Thin Film UltraFlex (TFUF) Program is to mature and validate the use of advanced flexible thin film photovoltaics blankets as the electrical subsystem element within an UltraFlex solar array structural system. In this program operational prototype flexible array segments, using United Solar amorphous silicon cells, are being manufactured and tested for the flight qualified UltraFlex structure. In addition, large size (e.g. 10 kW GEO) TFUF wing systems are being designed and analyzed. Thermal cycle and electrical test and analysis results from the TFUF program are presented. The purpose of the second program entitled, Low Cost/Mass Electrostatically Clean Solar Array (ESCA) System, is to develop an Electrostatically Clean Solar Array meeting NASA s design requirements and ready this technology for commercialization and use on the NASA MMS and GED missions. The ESCA designs developed use flight proven materials and processes to create a ESCA system that yields low cost, low mass, high reliability, high power density, and is adaptable to any cell type and coverglass thickness. All program objectives, which included developing specifications, creating ESCA concepts, concept analysis and trade studies, producing detailed designs of the most promising ESCA treatments, manufacturing ESCA demonstration panels, and LEO (2,000 cycles) and GEO (1,350 cycles) thermal cycling testing of the down-selected designs were successfully achieved. The purpose of the third program entitled, "High Power Platform for the Stretched Lens Array," is to develop an extremely lightweight, high efficiency, high power, high voltage, and low stowed volume solar array suitable for very high power (multi-kW to MW) applications. These objectives are achieved by combining two cutting edge technologies, the SquareRigger solar array structure and the Stretched Lens Array (SLA). The SLA SquareRigger solar array is termed SLASR. All program objectives, which included developing specifications, creating preliminary designs for a near-term SLASR, detailed structural, mass, power, and sizing analyses, fabrication and power testing of a functional flight-like SLASR solar blanket, were successfully achieved.

Eskenazi, Mike↗

NASA NTRS2002

The Stretched Lens Array (SLA): An Ultra-Light Photovoltaic Concentrator

A high-performance, ultralight, photovoltaic concentrator array is being developed for space power. The stretched lens array (SLA) uses stretched-membrane, silicone Fresnel lenses to concentrate sunlight onto triple-junction photovoltaic cells. The cells are mounted to a composite radiator structure. The entire solar array wing, including lenses, photovoltaic cell flex circuits, composite panels, hinges, yoke, wiring harness, and deployment mechanisms, has a mass density of 1.6 kg/sq.m. NASA Glenn has measured 27.4% net SLA panel efficiency, or 375 W/sq.m. power density, at room temperature. At GEO operating cell temperature (80 C), this power density will be 300 W/sq.m., resulting in more than 180 W/kg specific power at the full wing level. SLA is a direct ultralight descendent of the successful SCARLET array on NASA's Deep Space 1 spacecraft. This paper describes the evolution from SCARLET to SLA, summarizes the SLA's key features, and provides performance and mass data for this new concentrator array.

ONeill, Mark J.↗

NASA NTRS2002

34% Efficient InGaP/GaAs/GaSb Cell-Interconnected-Circuits for Line-Focus Concentrator Arrays

While monolithic multi-junction cells are preferred for flat plate arrays, mechanically stacked multi-junction cells are superior for solar concentrator applications. Reasons for this are that the mechanical stacked configuration with high efficiency Gallium Antimonide cells allows utilization of a much wider range of the solar energy spectrum, and the ability to use voltage matched interconnects results in full use of low bandgap cell currents. Herein, data are presented for simple two terminal voltage-matched circuits using InGaP/GaAs/GaSb stacked cells showing 34% average circuit efficiency for a lot of 12 circuits given prismatic covers. These circuits have been designed to fit into the ultralight Stretched Lens Array being developed by NASA. With these new cell-interconnected-circuits, we project that the power density at GEO operating temperature can be increased from 296 W/m2 to 350 W/m2 while maintaining the specific power at 190 W/kg at the full wing level.

Fraas, L. M.↗

NASA NTRS2002

Development of the Ultra-Light Stretched Lens Array

At the last IEEE (Institute of Electrical and Electronics Engineers) PVSC (Photovoltaic Specialists Conference), the new stretched lens array (SLA) concept was introduced. Since that conference, the SLA team has made significant advances in the SLA technology, including component level improvements, array level optimization, space environment exposure testing, and prototype hardware fabrication and evaluation. This paper will describe the evolved version of the SLA, highlighting the improvements in the lens, solar cell, rigid panel structure, and complete solar array wing. The near term SLA will provide outstanding wing level performance: greater than 180 W/kg specific power, greater than 300 W/sq m power density, greater than 300 V operational voltage, and excellent durability in the space environment.

O'Neill, M. J.↗

NASA NTRS2002

The Stretched Lens Array (SLA): A Low-Risk, Cost-Effective Array Offering Wing-Level Performance of 180 W/KG and 300 W/M2 at 300 VDC

At IECEC 2001, our team presented a paper on the new stretched lens array (SLA), including its evolution from the successful SCARLET array on the NASA/JPL Deep Space 1 spacecraft. Since that conference, the SLA team has made significant advances in the SLA technology, including component-level improvements, array-level optimization, space environment exposure testing, and prototype hardware fabrication and evaluation. This paper describes the evolved version of the SLA, highlighting recent improvements in the lens, solar cell, photovoltaic receiver, rigid panel structure, and complete solar array wing.

ONeill, Mark↗

NASA NTRS2000

Ultralightweight Fresnel Lens Solar Concentrators for Space Power

The first phase of this project was completed in March 2000, and included the successful technology demonstration of a new ultralightweight photovoltaic concentrator array at the fully functional panel level. The new array is called the Stretched Lens Aurora (SLA) array, and uses deployable, flexible, thin-film silicone rubber Fresnel lenses to focus sunlight onto high efficiency multijunction solar cells, which are mounted to a composite radiator surface for waste heat dissipation. A prototype panel was delivered to NASA Marshall in March 2000, and comprised four side-by-side lenses focussing sunlight onto four side-by-side photovoltaic receivers. This prototype panel was tested by NASA Glenn prior to delivery to NASA Marshall. The best of the four lens/receiver modules achieved 27.4% efficiency at room temperature in the NASA Glenn solar simulator tests. This performance equates to 375 W/sq.m. areal power and 378 W/kg specific power at the fully functional panel level. We believe this to be the first space solar array of any kind to simulataneously meet the two long-standing NASA goals of 300 W/sq.m. and 300 W/kg at the functional panel level. Key results for the first phase of the program have been documented by ENTECH in a Draft Final Technical Report, which is presently being reviewed by NASA, and which should be published in the near future.

ONeill, M. J.↗