Lawrence Livermore National Laboratory



Adam Mclean

Overview

The primary goal of this project was improving theoretical models and the interpretability of plasmas near the ionizing/recombining balance to advance predictive capability for divertor performance in state-of-the-art fluid-based modeling codes. To achieve this goal, we identified contributors to a universal shortfall in predicted radiation, the underestimated impact of convective plasma drifts/flows, and the role of molecules in cold plasmas in the DIII-D National Fusion Facility using newly installed multispectral extreme ultraviolet and visible spectroscopy and advanced boundary modeling developed by Lawrence Livermore National Laboratory.

Key Laboratory spectroscopic and modeling capabilities were successfully applied to a range of ionizing and recombining plasmas in a magnetically-confined fusion device to elucidate the roles of physical processes relevant to the detached divertor regime which is essential for operation of future fusion power reactors. As a result, a powerful array of spectroscopic diagnostics that are each unique worldwide have been added to the DIII-D device for continued use in coming operational campaigns, including research in boundary and core-edge integration to further expand operational space. Experiments scanning the detached regime resulted in application of essential missing physics with plasma-boundary codes and a recognition among international magnetic fusion programs of the formidable influence of convective plasma transport due to drifts in regimes, including conditions necessary for future fusion power reactors.

Impact on Mission

The integration of advanced plasma diagnostic systems and modeling capability is the forward-looking critical element in this work. Our research leveraged the Laboratory's core competencies in high-energy-density science and high-performance computing, simulation, and data science. Our results provide a unique opportunity to employ key Laboratory capabilities to quantify the role of targeted physical atomic and plasma processes in the divertor throughout the transition from attached to fully detached divertor conditions in DIII-D. Such capabilities are of keen interest to fusion laboratories nationally and internationally and are prime techniques and instruments for eventual application in future tokamaks within the U.S., Europe, China, and South Korea. Multiple systems added as part of our project are portable for application on other fusion devices, including the WiSE and the HR-VUV instruments.

This project led to development of an array of integrated diagnostic systems that will be valuable diagnostic tools for future experiments on the DIII-D device on a continuing basis. Additionally, as a direct consequence of experience and expertise gained operating and maintaining the DivSPRED device, the Laboratory became the custodian of the core SPRED device on DIII-D, with upgrade responsibilities.

Publications, Presentations, Etc.

McLean, A., et al. 2017. "Advancing Understanding and Predictive Capability in Boundary Plasma Science." Oral presentation, DIII-D Program Advisory Committee Meeting, San Diego, CA, March 2017. LLNL-PRES-727602.

——— . 2017. "Divertor Extreme Ultraviolet (EUV) Survey Spectroscopy on DIII-D." American Physical Society Division of Plasma Physics Annual Meeting, Milwaukee, WI, October 2017. LLNL-ABS-734830.

——— . 2018. "Divertor Extreme Ultraviolet (EUV) Survey Spectroscopy on DIII-D." LLNL-POST-741510.

——— . 2018. "Understanding Plasma Divertor Detachment in Magnetic Fusion Energy Tokamaks." LLNL-PRES-751340.

——— . 2018. "Extreme Ultraviolet (EUV) Spectroscopy in the Divertor of DIII-D." High Temperature Plasma Diagnostics Conference, San Diego, CA, April 2018. LLNL-PRES-753122, LLNL-ABS-744447, LLNL-POST-749800.

——— . 2018. "Power Accounting Using Divertor Extreme Ultraviolet Emission in the Transition to Detachment on DIII-D." International Conference on Plasma Surface Interactions in Controlled Fusion Devices, Princeton, NJ, June 2018. LLNL-ABS-744450.

——— . 2018. "Quantification of Radiating Species in the DIII-D Divertor in the Transition to Detachment Using Extreme Ultraviolet Spectroscopy." International Atomic Energy Agency Fusion Energy Conference, Ahmedabad, India, 2018. LLNL-ABS-752161.

——— . 2018. "Quantification of Radiating Species in the DIII-D Divertor in the Transition to Detachment Using Extreme Ultraviolet Spectroscopy." Proceedings of the 27th IAEA Fusion Energy Conference (2018) IAEA-CN-123/45. LLNL-PROC-759009.

Jarvinen, A., et al. 2018. "Progress in DIII-D Towards Validating Divertor Power Exhaust Predictions." Proceedings of the 27th IAEA Fusion Energy Conference (2018) IAEA-EX/9-3. LLNL-CONF-758951.

——— . 2018. "Progress in DIII-D Towards Validating Divertor Power Exhaust Predictions." International Atomic Energy Agency Fusion Energy Conference, Ahmedabad, India, 2018. LLNL-ABS-752093.

——— . 2018. "Impact of Drifts on Divertor Power Exhaust in DIII-D." International Conference on Plasma Surface Interactions in Controlled Fusion Devices, Princeton, NJ, 2018. LLNL-ABS-742063.

——— . 2019. "Role of Poloidal ExB Drift in Divertor Heat Transport in DIII-D." International Workshop on Plasma Edge Theory in Fusion Devices, La Jolla, CA, 2019. LLNL-POST-788431.

——— . 2019. "Use of VUV Spectroscopy in Validation of DIII-D Boundary Science During Radiative Divertor Operation." International Conference on Atomic Processes in Plasmas, Gaithersburg, MD, 2019. LLNL-ABS-779521.

——— . 2019. "Role of Poloidal ExB Drift in Divertor Heat Transport in DIII-D." American Physical Society Division of Plasma Physics Annual Meeting, Fort Lauderdale, FL, 2019. LLNL-PRES-795851.

——— . 2019. "Impact of Drifts on Divertor Power Exhaust in DIII-D." Nuclear Materials and Energy 19 (May 2019): 230-238. doi:10.1016/j.nme.2019.02.023. LLNL-JRNL-755620.

——— . 2019. "Radiative Power Exhaust Research at DIII-D - From Divertor Science to Core-Edge Integration of High Performance Plasmas." IAEA Technical Meeting on Divertor Concepts, Vienna, Austria, 2019. LLNL-ABS-780043.

Samuell, C., et al. 2018. "Comparing Definitions of Detachment on DIII-D." American Physical Society Division of Plasma Physics Annual Meeting, Portland, OR, 2018. LLNL-POST-779849.