D. Voorhees

Soft-x-ray amplification in lithiumlike Al xi (154 Å) and Si xii (129 Å)

Recent experiments on soft-x-ray amplification in lithiumlike ions in a CO2 laser-produced recombining plasma in a magnetic field are presented. The maximum gain–length (GL) products observed are GL ≃ 3–4 for confined the 154-A 4f–3d transition in Al xi and GL ≃ 1–2 for the 129-A 4f–3d transition in Si xii. A one-dimensional hydrodynamic code with a collisional-radiative atomic model was used to model the plasma, and the theoretical of gain agree well with the observations. Descriptions of both hydrodynamic and atomic physics codes predictions are given.

Measurement of population inversions and gain in carbon fiber plasmas

A CO/sub 2/ laser (approx.0.5 kJ energy, 50--80 ns pulse width) was focused onto the end of an axially oriented, thick (35--350 ..mu..) carbon fiber with or without a magnetic field present along the laser-fiber axis. We present evidence for axial-to-transverse enhancement of the C VI 182 A (n = 3--2) transition, which is correlated with the appearance of a population inversion between levels n = 3 and 2. For the B = 0 kG, zero field case, the maximum gain length product of klroughly-equal3 (kroughly-equal6 cm/sup -1/) was measured for a carbon fiber coated with a thin layer of aluminum (for additional radiation cooling). The results are interpreted in terms of fast recombination due mostly to thermal conduction from the plasma to the cold fiber core.

High‐temperature photochemistry reactor for kinetic studies of isolated elementary gas‐phase reactions

A reactor suitable for kinetic measurements on photolytically initiated elementary free‐radical reactions over approximately the 300–1900 K temperature range is described. Performance data are given for the O+CH4→OH+CH3 reaction.

Integration of the Tritium Purification System (TPS) into TFTR operations

The TPS is a hydrogen isotope separation system put into operation within the Tokamak Fusion Test Reactor (TFTR) tritium systems. The TPS extracts and purifies tritium from TFTR plasma exhausts, then returns it for reuse as plasma fueling. The TPS operates in two stages: separation of hydrogen isotopes from the TFTR plasma waste effluents via a Pd/Ag diffuser; and separation of hydrogen isotopes via a multi-stage cryogenic distillation system. TPS interfaces with the Gas Holding Tanks (GHTs), the Torus Cleanup System (TCS), the plant stack via the Tritiated Vent System, the Tritium Storage and Delivery System, and the Tritium Storage and Delivery Cleanup System (TSDCS). Commissioning of TPS included: operational testing at CFFTP and at Princeton, thorough helium and tritium leak checks a trial run with a limited tritium inventory (1000 Ci), and a 10000 Ci integrated systems test.

Measurement of multilayer mirror reflectivity and stimulated emission in the XUV spectral region

We present measurements of multilayer mirror reflectivity and stimulated emission in the XUV spectral region. A molybdenum–silicon multilayer mirror with 12% measured reflectivity at 182 A was found to produce a 120% enhancement of the C vi 182‐A line (3→2 transition) in a strongly recombining plasma. No such enhancement of the C v 186.7‐A line was seen, demonstrating amplification of stimulated emission at 182 A.

TFTR tritium accounting system for DT-operation

TFTR has been using tritium as a fuel gas as part of its Deuterium-Tritium (DT) experimental operations with over 600 kCi processed through the site and over 400 kCi injected. Careful inventory and accounting measures are required to ensure site and regulatory safety tritium limits are not exceeded. Tritium management is accomplished through a database system to coordinate experimental needs within these limits. A TFTR Nuclear Materials Custodian (NMC) oversees Tritium Transfer Operations (TTO) using accounts based on specific system physical locations including tritium product containers, uranium beds (hydration), Gas Holding Tanks (GHT), disposable Molecular Sieve Beds (DMSB), the Tritium Gas Injection System (TGIS), and the Tritium Purification System (TPS). Methods used to coordinate and track TTOs include: single source TTO serial numbers issued by the TFTR Shift Supervisor (TFTRSS) as TTO authorization, TTO verification receipts, and daily NMC database updates with reports issued to appropriate groups. Tokamak tritium operations are controlled and monitored through a computer system that automatically measures and generates tritium injection value reports, as well as providing interlocks between the TGIS and the personnel safety tritium monitors. This system also provides historical trends of tritium values in the entire TGIS, consisting of 14 injector volumes and an interconnecting manifold, to identify inter-system tritium leakage. NMC tritium accounting control involves aspects such as: tritium measurement data flow, verification, instrument calibration, measurement controls, TTO control limits, Material-in-Process (MIP) evaluation, database error detection and correction, and account material balances. Details of these areas are discussed with emphasis on the tight controls required for the very low tritium inventory level permitted for TFTR, and lessons learned from the past 23 months of tritium operations.

Development of small-scale soft-x-ray lasers: aspects of data interpretation

The widespread application of soft-x-ray laser technology is contingent on the development of small-scale soft-x-ray lasers that do not require large laser facilities. Progress in the development of soft-x-ray lasers that are pumped by a neodymium laser of energy 6–12 J is reported. Some aspects of data interpretation and gain measurements in such systems are discussed.

Recent experiments on soft x‐ray laser development in a confined plasma column

We present studies of magnetically confined and expanding recombining plasma columns and measurements of gain for hydrogen‐like (CVI) ions and population inversion for Li‐like (NeVIII) ions.

Tritium Analysis at TFTR

The tritium analytical system at TFRR is used to determine the purity of tritium bearing gas streams in order to provide inventory and accountability measurements. The system includes a quadrupole mass spectrometer and beta scintillator originally configured at Monsanto Mound Research Laboratory in the late 1970`s and early 1980`s. The system was commissioned and tested between 1991 and 1992 and is used daily for analysis of calibration standards, incoming tritium shipments, gases evolved from uranium storage beds and measurement of gases returned to gas holding tanks. The low resolution mass spectrometer is enhanced by the use of a metal getter pump to aid in resolving the mass 3 and 4 species. The beta scintillator complements the analysis as it detects tritium bearing species that often are not easily detected by mass spectrometry such as condensable species or hydrocarbons containing tritium. The instruments are controlled by a personal computer with customized software written with a graphical programming system designed for data acquisition and control. A discussion of the instrumentation, control systems, system parameters, procedural methods, algorithms, and operational issues will be presented. Measurements of gas holding tanks and tritiated water waste streams using ion chamber instrumentation are discussed elsewhere.

Soft x‐ray spectra, population inversions and gains in a recombining plasma column

Time integrated and time resolved soft x‐ray spectra have been measured from recombining CO2 laser produced plasmas. Determinations of population inversions and gain will be discussed.