A New Prototype Stage for Glancing-Angle–Deposition Coatings Research


Optical Manufacturing Process Engineer, John Spaulding, and Coating Operator, Justin Foster, are shown installing an optic on a new prototype stage built to support research and development work on glancing-angle–deposition (GLAD) coatings. The deposition system is designed to allow for growth of an oriented, birefringent film structure in stripes across an optical surface, and the resulting film thickness is controlled such that each stripe region is a quarterwave plate. GLAD coating research supports the potential manufacture of a distributed polarization rotator component that would be integral to beam-smoothing efforts for direct-drive or polar-direct-drive campaigns at the National Ignition Facility.

Shown here is John Spaulding and Justin Foster

John Spaulding and Justin Foster

X-Ray Backlighting of Cryogenic Capsule Implosion


A narrowband crystal imaging system was used to perform x-ray radiography of OMEGA cryogenic capsule implosions (see image above). A 20-ps, 1.5-kJ OMEGA EP laser pulse was used to irradiate a Si x-ray backlighter target located inside the OMEGA target chamber. This configuration made it possible to measure the x-ray absorption of the cold dense shell of DT with 15-µm spatial resolution.

Shown here is a radiograph of a cryogenic implosion

Radiograph of a cryogenic implosion

Dr. Michael Rosenberg Receives Rosenbluth Award


Dr. Michael Rosenberg was selected to receive the prestigious Marshall Rosenbluth Award for Outstanding Doctoral Thesis given by the American Physical Society Division of Plasma Physics. The award citation states “for first experimental demonstration of the importance of kinetic and multi-ion effects on fusion rates in a wide class of inertial confinement fusion implosions, and for use of proton diagnostics to unveil new features of magnetic reconnection in laser-generated plasmas.” There are many aspects to Rosenberg’s thesis, but the most important and influential accomplishment was to discover, quantify, and document the existence and importance of kinetic and multi-ion effects in inertial confinement fusion plasmas and to clearly delineate the transition from the kinetic to the average-ion fluid description. His research was done at the Omega Laser Facility and the National Ignition Facility and leveraged techniques and instruments developed at the MIT High-Energy-Density Accelerator Facility.

Shown here is Dr. Michael Rosenberg

Dr. Michael Rosenberg

Physicists Find New Evidence for Helium “Rain” on Saturn


Research scientists Marius Adrien Millot (LLNL) and Stephanie Brygoo (CEA-France) are shown displaying a Science Magazine news article on their research at LLE. They used the OMEGA Laser System to demonstrate possible helium “rain” on Saturn to account for the unexpectedly high brightness for a normally cooling planet. The helium “rain,” occurring at pressures and temperatures that can be created using OMEGA, unleashes gravitational potential energy that makes Saturn more luminous. In addition to LLNL and CEA, scientists come from around the world to take advantage of the facilities at LLE.

Shown here is Marius Adrien Millot and Stephanie Brygoo

Marius Adrien Millot and Stephanie Brygoo

Dynamic Compression Sector Laser


LLE developed a 100-J UV laser and Target Area System for the Dynamic Compression Sector (DCS) at the Advanced Photon Source (APS) located at the Argonne National Laboratory near Chicago. This new research facility is operated by Washington State University under sponsorship from the National Nuclear Security Administration. LLE partnered with Logos Technologies to develop and build the high-energy laser, which is suitable for a broad range of applications. The Advanced Photon Source is a state-of-the-art user facility dedicated to dynamic-compression science, a field that researches materials under extreme conditions (large compressions, high temperatures, and large deformations).

Shown here is DCS laser at LLE, as viewed from the north, taken before it was disassembled for shipping to APS

KBframed 16-Image X-Ray Optic


The next-generation Kirkpatrick–Baez (KB) microscope employs new x-ray optics for use on OMEGA cryogenic target implosions. Developed by Senior Scientist Frederic J. Marshall, the 16-image KB optic fits onto an existing OMEGA KB microscope chassis. The optics (seen in the right side of the image) have been arranged so that the individual images fall onto the imaging elements of a fast framing camera. The framing camera is used to time-gate the images from each optic to produce a “movie” of the late stages of a cryogenic implosion with a frame-to-frame resolution of 30 ps. The compact mirrors have a demonstrated spatial resolution of ~5 µm. This unique combination of spatial and temporal resolution is an important addition to the diagnostic arsenal at LLE. The measurements from this new KB microscope will be used to infer the central pressure achieved in the cryogenic implosions, a key performance metric in establishing DT fusion ignition equivalence with the OMEGA laser.

Shown here is the next-generation Kirkpatrick–Baez microscope

The next-generation Kirkpatrick–Baez microscope

Multiple-Pulse Driver Line


The multiple-pulse driver line (MPD) provides on-shot co-propagation of two separate pulse shapes in all 60 OMEGA beams. Smoothing by spectral dispersion (SSD) bandwidth is applied to the picket pulse shape (pulse A) generated by the SSD driver. No bandwidth is applied to the pulse generated by the Phoenix (PHX) driver (pulse B). SSD is used to prevent early-time beam imperfections from imprinting onto the target. However, there is an energy penalty associated with running SSD, the bulk of which can be recovered if SSD is not applied during the main pulse.

Shown here is Laboratory Engineer Jeremy Zenkar (left) and OMEGA System Scientist Tanya Kosc (right) align a diagnostic supporting MPD

Multiple-Pulse Driver Line

Implosions on OMEGA Exceed 50-Gbar Hot-Spot Pressures


Hot-spot pressures greater than 50 Gbar were achieved in direct-drive layered DT cryogenic implosions on OMEGA. A combination of laser and target improvements on OMEGA, as well as upgraded nuclear and x-ray diagnostics, led to the >50-Gbar observation. These experiments are part of an LLE campaign to demonstrate fuel pressures of 100 Gbar—the pressure required to demonstrate hydrodynamic equivalence on OMEGA to a direct-drive–ignition capsule at the National Ignition Facility.

Shown here is Cryogenic DT target implosion creating a compressed fusion fuel pressure >50 Gbar

Magnetic Liner Inertial Fusion


The Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E) announced a two-year, $3.8 million award for Sandia National Laboratories and the LLE to study the potential of combining two different technologies to further advance their research efforts to produce controlled fusion reactions. The award seeks to build upon the successes of Sandia’s magnetized liner inertial fusion (MagLIF) concept. MagLIF is an innovative magneto-inertial fusion concept that exploits advances in pulsed-power technology.

“The ARPA-E award will fund research that will benefit from the existing strong collaborative effort between Sandia National Laboratories and LLE,” said Professor and LLE Director Robert L. McCrory. “LLE, with its 60-beam OMEGA and four-beam high-energy OMEGA EP lasers, and Sandia, with the world’s largest pulsed-power machine, Z, provide unique capabilities to explore a range of fusion parameters previously unexplored.”

“Creating a high-output reaction in a MagLIF plasma at Z should demonstrate the promise of the broader field of research we call magneto-inertial fusion–a potentially inexpensive form of fusion,” said project lead and Sandia manager Dan Sinars. “We hope that the results of our research will motivate more efforts in this area.”

Shown here is collaborators from Sandia National Laboratories and LLE perform experiments on the OMEGA EP Laser System that test the effects of applied magnetic fields on laser preheat in the MagLIF scheme

A schematic of the point design for laser-driven MagLIF on OMEGA

Next-Generation Cryogenic Target


A next-generation cryogenic target was developed that will employ a new mounting stalk that is specifically designed to be insensitive to vibrational energy once aligned to the 60 beams of the OMEGA laser. Referred to as the “Type 1E target mount,” the new stalk was adapted by Mechanical Engineering’s Brian Rice from an original design by David Harding and Mark Bonino and uses a 17-µm-diam silicon carbide fiber to attach the cryogenic capsule to a polyimide tube that helps damp vibrations. The alignment-stability requirement is ~1% of the capsule diameter. These targets are filled with several hundred atmospheres of deuterium-tritium fuel and cooled to 19.6 K, or -424°F. Mathematical models, based on mechanical properties measured at 19.6 K, were used to select the target assembly materials and dimensions needed to ensure the stability requirement. Once irradiated by the 60 OMEGA beams, these capsules implode and produce a fusion energy yield of ~5 x 1013 DT neutrons which is ~100 J of fusion energy.

Shown here is type 1E target mount

Type 1E target mount