From: Kim's Connection <-------@llnl.gov>
Sent: Thursday, August 12, 2021 11:28 AM
To: Kim's Connection <LABEMPLOYEES@llnl.gov>
Subject: [EXT] Special edition! Director's Update August 12, 2021



Colleagues,



You have all heard me talk many times about the central role that pursuit of fusion ignition as a gateway to high yield plays in stockpile stewardship and the importance of facilities like NIF to advance our knowledge, test our hypotheses, and challenge our people. These complex inertial confinement fusion (ICF) experiments seek to very rapidly compress a small pellet filled with deuterium (D) and tritium (T) (essentially ‘heavy’ hydrogen) to extremely high temperatures and pressures, causing the DT atoms to fuse together and release significant energy before the capsule falls apart. Over the past year our ICF research teams have made significant strides toward that goal, achieving record yields over 150 kJ with two different target types earlier this year. Those results were our first clear indication that we were moving into the realm where the physics changes fast and the ignition threshold was perhaps within sight.



On Sunday afternoon, another barrier was shattered. Our most recent ICF experiment produced a yield of more than 1 MJ, a 6X improvement over the prior record and a yield from the fusion capsule that was more than 4X the energy that the capsule absorbed. This result is historic in many respects and represents the culmination of more than 60 years of hard work, innovation and ingenuity, and relentless focus on the ultimate goal. Because of the extremely high yield of this shot, the full analysis of the data will take some time and the team will be hard at work vetting their analyses and preparing publications for the peer reviewed literature. Of course, this is only the first step and significant work remains. The team is already planning future experiments to explore the conditions that led to this remarkable advance and working to repeat and build upon this result.



This experiment, which produced a fusion yield of about 2/3rd of the delivered laser energy, puts us within striking distance of the “gain greater than unity” benchmark, where the fusion yield produced would be greater than the laser energy delivered, put forward in a 1997 review of the NIF by the National Academy of Sciences. To understand the importance of this we need to remember the context. In 1972, John Nuckolls first published the idea that high power lasers could be used to implode a capsule containing DT fuel to achieve thermonuclear burn in the laboratory. Over the intervening decades, numerous approaches were tried and steadily our understanding and the required technologies were advanced, starting from ~1 kJ lasers to today’s 2 MJ at NIF, a more than 1000X increase in laser energy to cite just one. Controlled thermonuclear fusion in the laboratory remains one of the defining scientific grand challenges of this era and this is a momentous step forward.



Sunday’s experiment built on advances and insights developed over the last several years by a Lab-wide team working on NIF and included advances in theory and simulation tools; new diagnostics; target fabrication improvements in the hohlraum, capsule shell, and fill tube; improved laser precision; and design changes to increase the energy coupled to the implosion and the compression of the implosion. This result was enabled by sustained support from an enormous range of partners, collaborators, and stakeholders including our partners at Los Alamos National Lab, Sandia National Lab, the University of Rochester Laboratory for Laser Energetics, General Atomics, the academic community, industry, and the DOE/NNSA.  This advance opens the door to exciting new NIF applications to support stockpile stewardship, enables us to study robustly burning plasmas for the first time since underground testing ended, and creates new possibilities to get to much higher fusion yields on NIF. It truly is the first step into a very bright future and a moment of enormous pride for the entire Laboratory.



Take care and stay safe,



Kim