@article{gray_may_bourham_2005, title={Quasi-steady state, low current behaviour of a magnetized coaxial plasma source}, volume={14}, ISSN={["0963-0252"]}, DOI={10.1088/0963-0252/14/4/010}, abstractNote={The Coaxial Plasma Source-1 facility (Mayo R M et al 1995 Plasma Sources Sci. Technol. 4 47) was modified from a short pulse, high current (SPHC) pulse forming network (PFN) with very low inductance (∼200 nH) to a large inductance ladder circuit. This modification allows for a longer, flat top gun current pulse that eliminates the under-damped, sinusoidal behaviour of the gun current with consequent interruptions in plasma parameters. The new PFN was designed to produce a current waveform for a much longer period (∼1 ms). As a consequence of increasing the pulse length, the magnitude of the gun current was reduced as no additional energy storage was added to the PFN. The characterization of the electrical and plasma behaviour of the experiment operated with the long pulse, low current (LPLC) PFN is presented. The gun currents produced by the LPLC PFN are approximately one-fifth in magnitude of the gun currents produced by the SPHC PFN. Axial plasma parameters were measured near the muzzle of the plasma source, and electron densities were found to range from 1 × 1019 m−3 to 7 × 1019 m−3 depending upon the axial location. These values are approximately 1–2 orders of magnitude less than the electron densities produced by the SPHC PFN at the same locations. Electron temperatures range from 30 to 60 eV at these locations and are very similar to those produced by the SPHC PFN. A resistive MHD model was applied as an order estimate of the plasma resistivity and demonstrates reasonable agreement with measured values of the magnetized coaxial gun resistance.}, number={4}, journal={PLASMA SOURCES SCIENCE & TECHNOLOGY}, author={Gray, TK and May, RM and Bourham, MA}, year={2005}, month={Nov}, pages={712–721} }
 @article{maingi_bell_bell_bush_fredrickson_gates_gray_johnson_kaita_kaye_et al._2003, title={H-mode research in NSTX}, volume={43}, ISSN={["0029-5515"]}, DOI={10.1088/0029-5515/43/9/322}, abstractNote={H-modes are routinely obtained in the National Spherical Torus Experiment (NSTX) and have become a standard operational scenario. L–H transitions triggered by NBI heating have been obtained over a wide parameter range in Ip, Bt, and n̄e in either lower-single-null (LSN) or double-null (DN) diverted discharges. Edge localized modes are observed in both configurations but the characteristics differ between DN and LSN, which also have different triangularities (δ). An H-mode duration of 500 ms was obtained in LSN, with a total pulse length of ∼1 s. Preliminary power threshold studies indicate that the L–H threshold is between 600 kW and 1.2 MW, depending on the target parameters. Gas injector fuelling from the centre stack (i.e. the high toroidal field side) has enabled routine H-mode access, and comparisons with low-field side (LFS) fuelled H-mode discharges show that the LFS fuelling delays the L–H transition and alters the pre-transition plasma profiles. Gas puff imaging and reflectometry show that the H-mode edge is usually more quiescent than the L-mode edge. Divertor infrared camera measurements indicate up to 70% of available power flows to the divertor targets in quiescent H-mode discharges.}, number={9}, journal={NUCLEAR FUSION}, author={Maingi, R and Bell, MG and Bell, RE and Bush, CE and Fredrickson, ED and Gates, DA and Gray, T and Johnson, DW and Kaita, R and Kaye, SM and et al.}, year={2003}, month={Sep}, pages={969–974} }
 @article{sood_gardner_gray_2000, title={Steady neutron source measurement method for Sigma(a) and Sigma(s) in geological samples}, volume={53}, ISSN={["0969-8043"]}, DOI={10.1016/S0969-8043(00)00235-9}, abstractNote={An improved experimental method, using a steady neutron source in a moderating medium, has been developed to determine thermal neutron absorption and scattering cross sections for bulk geological media using discrete samples. The system design has been optimized and experimental results have been benchmarked using Monte Carlo simulation. Studies have been performed to improve the measurement sensitivity and reproducibility over previous designs. A semi-empirical model has been developed for determining both absorption and scattering cross sections of the sample.}, number={4-5}, journal={APPLIED RADIATION AND ISOTOPES}, author={Sood, A and Gardner, RP and Gray, TK}, year={2000}, pages={603–616} }