Howard Thomas Powell

Howard Thomas Powell, a noted laser physicist and contributor to the inertial confinement fusion (ICF) program at Lawrence Livermore National Laboratory (LLNL), died suddenly of an apparent heart attack on 15 November 2000 while attending to laboratory business in Washington, DC. A leader in the development of high-power gas and solid-state laser systems for almost three decades, Howard was internationally renowned for his contributions.

Howard came from humble beginnings. Born on 2 October 1944, he was reared in Woodland, a small logging town in Washington State. The son of a logger, he graduated from Caltech in 1966 with a BS in physics. He received his PhD in applied physics from Cornell University in 1971 under George J. Wolgal. His thesis topic was “Inhomogeneous Saturation and Self-Pulsing in the CO₂ Laser.”

Howard continued postdoctoral research at Cornell before going, in late 1971, to the McDonnell Douglas Research Laboratories in St. Louis, Missouri, as a research physicist. In 1973, Howard joined LLNL as a staff scientist in the laser division; there, he made several major contributions to gas lasers. In 1974, Howard and his colleagues reported lasing in the green from the transient diatomic molecule xenon oxide and demonstrated lasing on the auroral transition of oxygen in electron beam-pumped mixtures of krypton and oxygen. Stimulated emission on the auroral and transauroral lines in selenium was reported in 1978 and lasing of atomic sulfur was realized in 1979. This seminal work on excimer molecular lasers paved the way for subsequent research on diatomic excimer molecules and the rare gas-halide lasers, in particular, that are now used worldwide in applications such as photolithography, medical procedures, and materials processing. In 1976, Howard codiscovered the krypton chloride ultraviolet excimer laser and was an early leader in exploring the feasibility of the krypton fluoride laser as a driver for ICF.

Throughout the 1980s and 1990s, he was a pioneer in the development of solid-state lasers, particularly in flashlamp pumped neodymium:glass amplifiers for ICF. In 1988, he led the Precision Nova campaign, which laid the groundwork for establishing LLNL’s readiness to begin work on the National Ignition Facility. Adopting the pioneering work by scientists in Japan and the US, Howard also led the deployment of beam smoothing on the Nova laser—a feature now recognized as essential for all approaches to laser-driven ICF. In 1994, Howard founded and led LLNL’s laser science and technology program, which achieved many successes, including the first demonstration of a petawatt laser, development of high-average-power femtosecond lasers and repetitively pulsed diode-pumped lasers, demonstration of laser-generated neutrons, and development of large-aperture diffractive optics.

In addition to his numerous scientific achievements, Howard inspired young scientists and engineers, and was an unusually effective mentor known for his integrity and passion for science. He particularly loved to bring science to young people by visiting his local high school as a guest speaker. He attracted a considerable number of scientists to LLNL and set an example that engendered trust and devotion.

In addition to being a distinguished man of science, Howard had a deep appreciation of art. He had a particular fondness for American history and was an avid collector of early American furniture and glassware. He was also an aspiring vintner; he and his wife enjoyed growing grapes and producing wine. Howard was deeply involved in his Livermore, California, community both as a soccer coach for many years and as a long-time member of the Livermore Valley Tennis Club. He also loved the outdoors and spent many happy vacations in wilderness areas around the country.

Howard has left an indelible mark on laser science and technology, ICF, and LLNL. Beyond his scientific and technical accomplishments, he was widely respected and admired for his affable personality, his mentoring of young scientists, and his friendship to all he encountered. He will be sorely missed by his surviving family, his staff at LLNL, and his numerous colleagues in the international community who were the beneficiaries of his scientific acumen and warm personality.