Progress in pulsed power fusion

Pulsed power offers and efficient, high energy, economical source of x-rays for inertial confinement fusion (ICF) research. We are pursuing two main approaches to ICF driven with pulsed power accelerators: intense light ion beams and z-pinches. This paper describes recent progress in each approach and plans for future development

Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

Pulsed Power Fusion Program update

The US Department of Energy has supported a substantial research program in Inertial Confinement Fusion (ICF) since the early 1970s. Over the course of the ensuing 25 years, pulsed power energy, efficiency, and relatively low cost of the technology when compared to the mainline ICF approach involving large glass lasers. These compelling advantages of pulsed power, however, have been tempered with the difficulty that has been encountered in concentrating the energy in space and time to create the high energy and power density required to achieve temperatures useful in indirect drive ICF. Since the Beams `96 meeting two years ago, the situation has changed dramatically and extremely high x-ray power ({approximately}290 TW) and energy ({approximately}1.8 MJ) have been produced in fast x-pinch implosions on the Z accelerator. These sources have been utilized to heat hohlraums to >150 eV and have opened the door to important ICF capsule experiments

X-1: The Challenge of High Fusion Yield

In the past three years, tremendous strides have been made in X-ray production using high-current Z-pinches. Today, the X-ray energy and power output of the Z accelerator (formerly PBFA II) is the largest available in the laboratory. These Z-pinch X-ray sources have great potential to drive high-yield inertial confinement fusion (ICF) reactions at affordable cost if several challenging technical problems can be overcome. Technical challenges in three key areas are discussed in this paper: the design of a target for high yield, the development of a suitable pulsed power driver, and the design of a target chamber capable of containing the high fusion yield

Sandia National Laboratories participation in the National Ignition Facility project

The National Ignition Facility is a $1.1B DOE Defense Programs Inertial Confinement Fusion facility supporting the Science Based Stockpile Stewardship Program. The goal of the facility is to achieve fusion ignition and modest gain in the laboratory. The NIF project is responsible for the design and construction of the 192 beam, 1.8 MJ laser necessary to meet that goal. - The project is a National project with participation by Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), Sandia National Laboratory (SNL), the University of Rochester Laboratory for Laser Energetics (URLLE) and numerous industrial partners. The project is centered at LLNL which has extensive expertise in large solid state lasers. The other partners in the project have negotiated their participation based on the specific expertise they can bring to the project. In some cases, this negotiation resulted in the overall responsibility for a WBS element; in other cases, the participating laboratories have placed individuals in the project in areas that need their individual expertise. The main areas of Sandia`s participation are in the management of the conventional facility design and construction, the design of the power conditioning system, the target chamber system, target diagnostic instruments, data acquisition system and several smaller efforts in the areas of system integration and engineering analysis. Sandia is also contributing to the technology development necessary to support the project by developing the power conditioning system and several target diagnostics, exploring alternate target designs, and by conducting target experiments involving the ``foot`` region of the NIF power pulse. The project has just passed the mid-point of the Title I (preliminary) design phase. This paper will summarize Sandia`s role in supporting the National Ignition Facility and discuss the areas in which Sandia is contributing. 3 figs

Particle beam interactions with plasmas and their application to inertial fusion

Present day target designs indicate that particle beams with 1-10 MJ and 100-500 TW, focused to intensities around 100 TW/cm2 will be required to ignite targets with gains of 10-100. Due to uncertainties about the symmetry and stability of the implosion, these requirements may change by as much as an order of magnitude as more is learned. The particle beams will interact with target plasmas which have temperatures of several hundred electron volts and densities up to solid density. Under these conditions the main energy-loss mechanism is collisional, however, in the case of electrons, the orbits can be substantially altered by electric and magnetic fields. Experiments with thin foils have measured energy deposition enhancement by a factor of 5-10 with foils mounted in the anode, and by a factor of 20 or more with foils mounted on a stalk extending into the diode