Mr. James Hoag Profile

James Hoag

at AURA, Inc

SPIE Involvement:

Author

Publications (3)

Proceedings Article | 11 September 2024 Presentation + Paper

DKIST enclosure azimuth mechanism adjustments for improved performance and reliability

James Hoag, Heather Marshall, Paul Jeffers

Proceedings Volume 13094, 130940C (2024) https://doi.org/10.1117/12.3019217

KEYWORDS: Tolerancing, Design, Finite element methods, Deformation, Reliability, Telescopes

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The National Science Foundation’s Daniel K. Inouye Solar Telescope (DKIST) located on the summit of Haleakalā, Maui is the largest solar telescope in the world. Housing a 4-meter off-axis primary mirror and a highly advanced adaptive optics system, DKIST is enabling observations of specific regions of the Sun in higher resolution and greater detail than any preexisting ground-based telescope. The DKIST Enclosure Azimuth Mechanism is responsible for accurate positioning of the Enclosure in azimuth and provides a second degree of freedom to the altitude movement of the Enclosure Shutter which enables an overall position accuracy of 19 arcmin point-to-point at the Enclosure Aperture. The mechanism is primarily comprised of sixteen track rail segments, eight driven bogies, and two idler bogies, and it serves as the interface between the fixed support building Ring Girder structure and the rotating Enclosure structure. Visual observations and control system torque data have shown evidence of a loss of contact at the interface between the individual bogie wheels and the track rail. This loss of contact results in imbalanced loading conditions that impact performance and reliability as loads are varied in proportion to the number of wheels in contact. In addition, visual inspections have shown early indications of rolling contact fatigue at specific azimuth locations of the track rails due to high contact stresses. As a result, a project was initiated to improve load sharing and maintain tracking accuracy by minimizing pointing error deviations that result from rail flatness tolerances variations, unanticipated mechanical deformations from load imbalances, and varying control systems demands. In addition, equalizing the load balance will reduce unintended fatigue loading of the structural and mechanical components as well as reduce contact stresses in the rail sections improving overall mechanism reliability. The investigation, implementation, and evaluation of this process is presented herein.

Proceedings Article | 11 September 2024 Presentation + Paper

The US National Science Foundation Daniel K. Inouye Solar Telescope operations commissioning: results and lessons learned

Thomas Rimmele, Alexandra Tritschler, Andres Parraguez, Friedrich Wöger, Bret Goodrich, Luke Johnson, Heather Marshall, Paul Jeffers, Alisdair Davey, Robert Tawa, Gary Candido, David Boboltz, Tetsu Anan, Christian Beck, Gianna Cauzzi, Serena Criscuoli, André Fehlmann, Catherine Fischer, David Harrington, Sarah Jaeggli, Maxim Kramar, David Kuridze, Thomas Schad, Dirk Schmidt, Joao Manuel da Silva Santos, Lucas Tarr, Han Uitenbroek, James Arnow, Joel Davidow, Dale Deibert, Alysa Derks, Arthur Eigenbrot, Tony Hays, Erik Johansson, Daniel Spiess, Frazer Watson, Scott Wiant, Hillary Hope Head, David Morris, Manuel Díaz Alfaro, Nuria Wright-Garba, Anthony Santini, Andrew Beard, David Berst, Bryan Cummings, Andrew Ferayorni, Stephen Guzzo, John Hubbard, Jon Munoz, Isabell Scholl, Eric Cross, Colleen Donnelly, Steve O'Brien, Rodell Agdinaoay, Wade Bortz, Christopher Foster, Gary Foster, Chriselle Ann Galapon, Brian Gregory, Stephanie Guzman, Marco Guzman, James Hoag, Mary Liang, Karl Newman, Brialyn Onodera, Sebastien Poupar, Myles Puentes, Lukas Rimmele, Erik Starman, Stacey Sueoka, Richard Summers, Aimee Szabo, Louis Szabo, Timothy Williams, Charles White, Chad Bader, James Barry, Eric Bio, Terran Carter, Linda Evans, Bruce Keahi, Kealli Koki, Michael Lay, Aidan Lay, Justin Lay, Barry Poe, Norman Tong, Roberto Casini, Alfred deWijn, Jeffrey Kuhn, Haosheng Lin, Thomas Kentischer, Clemens Halbgewachs

Proceedings Volume 13094, 130940Y (2024) https://doi.org/10.1117/12.3022760

KEYWORDS: Equipment, Magnetism, Calibration, Adaptive optics, Tunable filters, Polarization, Solar telescopes, Solar processes, Optical filters, Sun

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Proceedings Article | 13 December 2020 Poster + Paper

Developing an install plan for the DKIST carousel cooling system

Brialyn Onodera, James Hoag, Chriselle Galapon Nagata

Proceedings Volume 11445, 1144541 (2020) https://doi.org/10.1117/12.2560893

KEYWORDS: Cooling systems, Solar telescopes, Cladding, Mirrors, Sun, Telescopes, Control systems, Solar radiation, Camera shutters

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