D. J. Wheeler

Microdischarge devices fabricated in silicon

Cylindrical microdischarge cavities 200–400 μm in diameter and 0.5–5 mm in depth have been fabricated in silicon and operated at room temperature with neon or nitrogen at specific power loadings beyond 10 kW/cm3. The discharges are azimuthally uniform and stable operation at N2 and Ne pressures exceeding 1 atm and ∼600 Torr, respectively, has been realized for 400 μm diameter devices. Spectroscopic measurements on neon discharges demonstrate that the device behaves as a hollow cathode discharge for pressures >50 Torr. As evidenced by emission from Ne and Ne+ (2P,2F) states as well as N2 (C→B) fluorescence (316–492 nm), these discharge devices are intense sources of ultraviolet and visible radiation and are suitable for fabrication as arrays.

Compact XeF (C -> A) and iodine laser optically pumped by a surface discharge.

A compact surface-discharge laser system has been developed and applied to optically pumping the bound → free XeF (C → A) transition that lases in the blue-green (475–490-nm) and the 2P1/2 → 2P3/2 transition of atomic iodine at 1.315 μm. Employing no high voltage or current switches and occupying only ~1 m2 of table space, this device has an active length of ~50 cm and at present dissipates >8 MW/cm of surface discharge for a stored energy of 2.5 kJ. With 5% output coupling at 485 nm, energies of >50 mJ are obtained on the XeF (C → A) transition in 1.5-μs (FWHM) pulses. The spectrum of the untuned oscillator is virtually free of absorption features and has a width of ~15 nm (FWHM). Pulse energies exceeding 0.7 J have been obtained for iodine at 1.3 μm with an output coupling of only 10%.

BOSS-LDG: A Novel Computational Framework That Brings Together Blue Waters, Open Science Grid, Shifter and the LIGO Data Grid to Accelerate Gravitational Wave Discovery

We present a novel computational framework that connects Blue Waters, the NSF-supported, leadership-class supercomputer operated by NCSA, to the Laser Interferometer Gravitational-Wave Observatory (LIGO) Data Grid via Open Science Grid technology. To enable this computational infrastructure, we configured, for the first time, a LIGO Data Grid Tier-1 Center that can submit heterogeneous LIGO workflows using Open Science Grid facilities. In order to enable a seamless connection between the LIGO Data Grid and Blue Waters via Open Science Grid, we utilize Shifter to containerize LIGO’s workflow software. This work represents the first time Open Science Grid, Shifter, and Blue Waters are unified to tackle a scientific problem and, in particular, it is the first time a framework of this nature is used in the context of large scale gravitational wave data analysis. This new framework has been used in the last several weeks of LIGO’s second discovery campaign to run the most computationally demanding gravitational wave search workflows on Blue Waters, and accelerate discovery in the emergent field of gravitational wave astrophysics. We discuss the implications of this novel framework for a wider ecosystem of Higher Performance Computing users.

Observation of individual particles and Coulombic solids in a microdischarge

Spherical particles /spl sim/10-35 /spl mu/m in diameter are intentionally introduced into a cylindrical microdischarge device fabricated in Al or Si. Having a diameter of 400 /spl mu/m, this device is viewed along its axis with a microscope and charge-coupled device camera. Individual particles suspended in discharges in Ne are readily observable and form stable spatial patterns (in the plane transverse to the microdischarge axis) determined by the interplay of electrostatic and ion drag forces. Microdischarges may well provide an ideal testbed for exploring the application of well-characterized particles as in situ probes of plasmas.

Characteristics of microdischarge devices in silicon

Summary form only given. We focus on a simpler discharge geometry that is more amenable to mass production. These devices consist of a Si cathode, a pyrex dielectric layer, and a Ni anode and differ from those previously reported in that the cathode is a plane rather than a cylinder. The devices are fabricated by drilling a hole in the pyrex using ultrasonic milling, anodically bonding the pyrex onto a silicon substrate, and then depositing the nickel anode.