Sandia's existence stems from its engineering support of the Manhattan Project during the 1940's to develop Nuclear Weapons (NWs), and its first and foremost mission remains engineering support for the NW program. This mission represents a significant fraction of the total effort at Sandia, which is administered by the National Nuclear Security Administration (NNSA). Not surprisingly, Center 1100 has had many core thrusts that have a rich history of contributing in important ways to NW mission needs. These past thrust activities have in many cases led to enduring applied research programs and unique capabilities with continuing important direct applications that support the evolving stockpile and nuclear nonproliferation. A significant fraction of the research in Center 1100 is therefore geared toward performing fore-front science that has either an immediate or the promise of future impact on the nation's nuclear arsenal. This R&D can be categorized under the following headings
Our expertise and facilities in radiation plasma and shock physics have always been actively involved in supporting the design and development of neutron generators. This is especially true today, since Sandia now has total responsibility (design, development and production) for these critical components. Crucial current activities that we are involved in include:
Two accelerator facilities in the Center are used for quantitative high-energy ion beam analysis of materials. These are the 2.5 MV Van de Graaff and the 6.5 MV Tandem Pelletron. Light elements (hydrogen to fluorine) are depth concentration profiled using heavy ion elastic recoil detection (ERD) and nuclear reaction analysis (NRA), while heavier elements are measured using backscattering spectrometry (e.g., RBS) and proton induced x-ray emission (PIXE). An external Micro Ion Beam Analysis (X-MIBA) capability enables multi-elemental analysis and ion irradiation of samples, which are vacuum incompatible or extraordinarily large, and is currently a main component of the Center's Homeland Security program where it is being used to detect radioactive particulates and measure compositional signatures. The Nuclear Microprobe with is used to study materials with 1 micron lateral resolution.
The capabilities of IBA are summarized in our IBA Periodic Table.
Plasma physics has been a part of the Laboratories research portfolio almost from the beginning of the laboratory. Recently, our historical expertise in this area has contributed to ongoing missions in the areas of fusion research, neutron generators, high power gas lasers, and microelectronics processing. In addition to our impact on Sandia missions, we have made significant contributions to external programs funded by private industry (Sematech, Applied Materials) and other governmental agencies.
The chemical complexity of most plasma systems coupled with the challenges of directly probing plasmas has led us to develop a portfolio of plasma diagnostic techniques that span the spectrum from dc to rf, microwaves, and light. In addition we have been instrumental in the development of a number of heavy particle beam and laser based techniques. Due to their complexity, many of these diagnostic techniques do not exist outside Sandia. We are recognized world leaders in the area of plasma diagnostics and are regularly invited to give talks reviewing our techniques, consult with a range of customers, and participate in program reviews.
Plasma physics is typically divided into high and low temperature regimes. The high temperature plasma work has primarily benefited the DOE Office of Science Program in Magnetic Fusion Energy (MFE). Early work in H retention in metals and nonmetals, including the low-Z materials used for Plasma Facing Components (PFCs) such as limiters and plates used in diverters, lead to physics models for this retention that was ultimately used to formulate the details of the successful DT Campaign at the Princeton Plasma Physics Lab so as to stay with a rather low tritium inventory limit. More recently, our work has been to understand and control impurity transport at the edge of current tokamaks (DIII-D and CMOD), and spherimaks (NSTX), and to perfect detached-plasma techniques that both benefit H recycling and reduce erosion of PFCs.
Low temperature plasma physics is typically defined as electron temperatures of less than 10 eV. In the commercial arena, plasmas of this type are critical for microelectronics plasma processing, fluorescent lighting, flat panel displays and televisions, remediation of toxic materials, surface cleaning, and atmospheric rf propagation effects in the ionosphere. Within Sandia, the current significant emphasis in the areas of neutron tube source design (see item on Neutron Generator Science below), microelectronics processing, and dusty plasmas. In what follows we highlight the latter two areas.
Thus, while plasma physics has been a part of the centers portfolio for a number of years, it continues to contribute to a range of laboratory missions. We are currently exploring new areas related to remediation of biomass, plasma-surface interactions, the use of plasmas for hypersonic aircraft control, and plasma assisted combustion for high altitude aircraft.
Shockwave physics at Sandia was born in a predecessor organization of Center 1100. The early work centered in part on material strength and survivability of weapon components and systems and to a larger extent on the development of novel concepts and materials for shock-actuated small pulse power sources. These sources became the active components in impact fuses and in explosively-driven ferroelectric and ferromagnetic firesets, and neutron generator power supplies. Concomitantly, we developed Sandia's first gas gun facility for controlled shockwave research, (still in use today) as well as a variety of shock diagnostic capabilities for both laboratory and underground experiments. We also performed research and developed considerable understanding of the shock initiation of explosives and used this knowledge to understand and help develop families of bridge-wire and slapper detonators. In some of these areas (ferroelectrics, encapsulants and dynamic piezoelectric stress gauges) Center 1100 remains the primary organization with the unique expertise and capabilities to address continuing needs.
Because shock experiments are expensive and their assembly is time consuming, early on Center 1100 established a static high pressure laboratory to complement the shock effort. This laboratory, which is still active today, allowed us to study in detail the phase diagrams of ferroelectric, ferromagnetic and other materials as well as their properties under pressure. Much of what we know about the physics and mechanisms of fire sets and neutron generator power supplies came from work in this laboratory. Recent work has been on PZT 95/5 and encapsulants in support of NG development and on slim-loop ferroelectrics (or relaxors) in support of firesets. This laboratory is also a critical resource for our BES-supported research on the fundamental physics of disordered ferroelectrics and dielectrics.
A few highlights of recent work follow:
The goal of Sandia's remote optical sensing program is to characterize and identify material located at some distance from the sensor. In the current program, the materials span the full range of radiological, chemical and biological materials located on the ground or in airborne plumes at distances from feet to UAV and satellite based systems. The huge span of this laboratory wide effort is rooted in our Center's historical investment in gas phase molecular spectroscopy and laser development.
When started more than a decade ago, this work initially focused on nuclear nonproliferation issues. Based upon our previous research in molecular spectroscopy, a UV laser based system was proposed, despite a prevailing opinion outside the laboratory that UV would not work. Exploiting our investment in nonlinear laser optics, a frequency agile UV laser with unprecedented performance was fielded. That fully mobile system not only proved the validity of UV laser-based remote sensing but is now the technique of choice for this work. Our success and subsequent mission growth into other areas has firmly established Sandia as leader in remote sensing technologies. We are regularly called upon to consult with a range of governmental agencies and serve on review panels. In keeping with our tradition of national service, our work in this area has been little reported in the general literature due to sensitive aspects of the program and technology.
While the current generation of tools has enabled a broad range of remote sensing missions, there remain a number of potential technologies and outstanding science questions that could be pursued to enable the next generation of systems. For example, compact and easily deployed micro-optical systems that contain the functionality of the larger laboratory systems would be of widespread interest. In addition, the general nature of UV laser based remote sensing makes it a flexible technology base to address the ever-widening array of national threats. Our work in these areas continues.
We have facilities for nuclear microscopy and radiation effects microscopy based on a 6.5 MV tandem Pelletron ion accelerator and 1.9 MeV/amu Radio Frequency Quadrupole LINAC Booster. We generate ion species from hydrogen to gold for radiation effects research The Sandia Nuclear Microprobe with micrometer size high-energy ion beams is used to microscopically study radiation effects in devices ranging from discrete transistors to state of the art integrated circuits. Three advanced diagnostic techniques were invented at Sandia: Single-Event-Upset Imaging, Ion-Beam-Induced-Charge-Collection Imaging (IBICC), and time-resolved IBICC. A recent development is the Ion Electron and Ion Photon Emission Microscopes (2001 and 2005 R & D-100 Award winners), which can perform radiation microscopy using very highly ionizing particles without focusing the ion beam. Most recently we have developed a dedicated endstation to expose discrete transistors to intense pulses of high energy heavy ions, e.g., 40 MeV Si ions, to simulate and study neutron damage effects using in situ Deep Level Transient Spectroscopy (DLTS).
REM was started at Sandia in 1990 with the invention of Single Event Upset (SEU)-Imaging. Since that time it has been used in three modes: (1) to perform basic research into the induction of charges into the circuit of an IC by energetic ions, (2) the pre-production testing of prototype circuits for SEUs, and (3) the post-production analysis of IC failures due to low resistance to SEUs. REM has had a significant impact on radhard IC design and manufacturing because of accomplishments using all three of these modes. Three selected examples are given here.