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J P Holder

Publications and source records attributed to J P Holder.

6 recordsLinked to original sources
PubMed2005

Radiation-driven hydrodynamics of high- hohlraums on the national ignition facility.

The first hohlraum experiments on the National Ignition Facility (NIF) using the initial four laser beams tested radiation temperature limits imposed by plasma filling. For a variety of hohlraum sizes and pulse lengths, the measured x-ray flux shows signatures of filling that coincide with hard x-ray emission from plasma streaming out of the hohlraum. These observations agree with hydrodynamic simulations and with an analytical model that includes hydrodynamic and coronal radiative losses. The modeling predicts radiation temperature limits with full NIF (1.8 MJ), greater, and of longer duration than required for ignition hohlraums.

Journal Article↗
PubMed2005

Experimental investigation of high-mach-number 3D hydrodynamic jets at the national ignition facility.

The first hydrodynamic experiments were performed on the National Ignition Facility. A supersonic jet was formed via the interaction of a laser driven shock ( approximately 40 Mbar) with 2D and 3D density perturbations. The temporal evolution of the jet's spatial scales and ejected mass were measured with point-projection x-ray radiography. Measurements of the large-scale features and mass are in good agreement with 2D and 3D numerical simulations. These experiments provide quantitative data on the evolution of 3D supersonic jets and provide insight into their 3D behavior.

Journal Article↗
PubMed2004

Surface charge compensation for a highly charged ion emission microscope.

A surface charge compensation electron flood gun has been added to the Lawrence Livermore National Laboratory (LLNL) highly charged ion (HCI) emission microscope. HCI surface interaction results in a significant charge residue being left on the surface of insulators and semiconductors. This residual charge causes undesirable aberrations in the microscope images and a reduction of the time-of-flight (T-O-F) mass resolution when studying the surfaces of insulators and semiconductors. The benefits and problems associated with HCI microscopy and recent results of the electron flood gun-enhanced HCI microscope are discussed.

Ions↗
PubMed2001

Evidence for highly charged ion Coulomb crystallization in multicomponent strongly coupled plasmas.

Multicomponent non-neutral ion plasmas in a Penning trap consisting of Be(+) and highly charged Xe ions, having different mass-to-charge ratios than Be(+), are cooled to form strongly coupled plasmas by applying a laser-based collisional cooling scheme. The temperature of the plasma was determined from a Doppler broadened transition in Be(+). For the Xe ions, which are centrifugally separated from the Be, the Coulomb coupling parameter was estimated to be approximately 1000. Molecular dynamics simulations of the ion mixture show ordered structures, indicating crystallization of the Xe.

Journal Article↗
PubMed1989

Pathophysiologic and anesthetic correlations of the prune-belly syndrome.

"Prune-Belly" is the name given to the disease which is characterized by a congenital wrinkled appearance of the abdomen. Usually, a triad of congenital anomalies highlights the components of the prune-belly syndrome. This triad consists of undescended testicles, abdominal musculature deficiency and urinary tract abnormalities. The previously described triad of the syndrome is by no means the total spectrum of the disease. Prune-belly syndrome is also associated with diseases of the respiratory, cardiovascular, skeletal, gastrointestinal and central nervous systems. Associated diseases of major body systems which are caused by renal and cardiopulmonary anomalies, as well as the surgical procedure to be performed, influence the plan for the administration of anesthesia. The nature of the genitourinary diseases in the prune-belly baby may obviate the need for surgical intervention as early as the neonatal period of life. Although this congenital disease occurs with some rarity, the gravity of the syndrome demands an in-depth knowledge of its pathophysiology in order to assure uncomplicated anesthetic care. Astute surveillance during preanesthetic, anesthetic, and postanesthetic management is germane to the prevention of mishaps.

Anesthesia↗