Capillary Injection System Research Articles

Tests of positive ion beams from a microwave ion source for AMS

A test facility has been constructed to evaluate high-current positive ion beams from small gaseous samples for AMS applications. The major components include a compact permanent magnet microwave ion source built at the AECL Chalk River Laboratory and now on loan from the University of Toronto, and a double-focusing spectrometer magnet on loan from Argonne National Laboratory. Samples are introduced by means of a silica capillary injection system. Loop injection into a carrier gas provides a stable feed for the microwave driven plasma. The magnetic analysis system is utilized to isolate carbon ions derived from CO 2 samples from other products of the plasma discharge, including argon ions of the carrier gas. With a smaller discharge chamber, we hope to exceed a conversion efficiency of 14% for carbon ions produced per atom, which we reported at AMS-7. The next step will be to construct an efficient charge-exchange cell, to produce negative ions for injection into the WHOI recombinator injector.

Local impurity puffing as a scrape-off layer diagnostic on the Alcator C-Mod tokamak

A capillary injection system has been installed on Alcator C-Mod which allows the localized introduction of gaseous species at a variety of poloidal locations. An experimental program has been undertaken to observe impurity puffs with a CCD camera through appropriate optical filters. The comet-like shape of an ion line emission plume formed in the region of an injection graphically displays the direction of background deuterium flow as well as that of the poloidal impurity ion drift. Parallel and cross-field one-dimensional fluid models are used to characterize the plume shapes and to deduce the background plasma temperature, the parallel flow velocity and the poloidal drift velocity of the impurity ion. Model results are benchmarked against simulations of DIVIMP, a Monte Carlo code, and fast scanning probe measurements. The experiments present a novel diagnostic technique to elucidate local edge impurity transport.

Rapid and efficient detection of single chromophore molecules in aqueous solution

The first experiments on the detection of single fluorescent molecules in a flowing stream of an aqueous solution with high total efficiency are reported. A capillary injection system for sample delivery causes all the dye molecules to pass in a diffusion-broadened stream within a fast-moving sheath flow, through the center of the tightly focused laser excitation beam. Single-molecule detection with a transit time of ~1 ms is accomplished with a high-quantum-efficiency single-photon avalanche diode and a low dead-time time-gating circuit for discrimination of Raman-scattered light from the solvent.

Direct quantification of ethyl carbamate in distilled alcoholic beverages using a cold capillary injection system and optimised selected ion monitoring

An integrated procedure is described which allows direct injection quantitative screening to single figure parts per billion (μg/L) levels of ethyl carbamate in the natural matrix of distilled alcoholic beverage. Injection and detection performance was studied and optimized to allow this routine, reproducible, trace analysis without any sample pre-treatment. All aspects of the analysis including autosampler run sequences and automated internal standard report generation are initiated and controlled from a single GC/MS workstation.