[en] An escaping alpha collector probe has been developed for TFTR's DT phase. Energy distributions of escaping alphas have been determined by measuring the range of α-particles implanted into nickel foils located within the alpha collector. Results at 1.0 MA of plasma current are in good agreement with predictions for first orbit alpha loss. Results at 1.8 MA, however, show a significant anomalous loss of partially thermalized alphas (in addition to the expected first orbit loss), which is not observed with the lost alpha scintillator detectors in DT plasmas, but does resemble the anomalous delayed loss seen in DD plasmas. None of the candidate explanations proposed thus far are fully consistent with the anomalous loss observations. An experiment designed to study the effect of plasma major radius shifts on α-particle loss has led to a better understanding of α-particle dynamics in tokamaks. Intuitively, one might suppose that confined marginally passing α-particles forced to move toward higher magnetic field during an inward major radius shift (i.e., compression) would mirror and become trapped particles, leading to increased alpha loss. Such an effect was looked for during the shift experiment, however, no significant changes in alpha loss to the 90 degree lost alpha scintillator detector were observed during the shifts. It is calculated that the energy gained by an α-particle during the inward shift is sufficient to explain this result. However, an unexpected loss of partially thermalized α-particles near the passing/trapped boundary was observed to occur between inward and outward shifts at an intermediate value of plasma current (1.4 MA). This anomalous loss feature is not yet understood

[en] Alpha particle loss to the wall of TFTR has been measured during the initial TFTR DT run period. These measurements were made with the same lost alpha scintillator detector system used previously for DD fusion products, except for a switch of the scintillator material from zinc sulfide (P31) to yttrium aluminate (P46) to insure a linear response up to the maximum alpha flux expected in DT. The alpha loss signals in DT are ∼ 100 times larger than the DD fusion product loss signals, as expected from the neutron rates and the relative sensitivity to DT vs. DD fusion products

[en] Alpha particle loss was measured during the TFTR DT experiments using a scintillator detector located at the vessel bottom in the ion grad-B drift direction. The DT alpha particle loss to this detector was consistent with the calculated first-orbit loss over the whole range of plasma current I=0.6-2.7 MA. In particular, the alpha particle loss rate per DT neutron did not increase significantly with fusion power up to 10.7 MW, indicating the absence of any new ''collective'' alpha particle loss processes in these experiments

[en] We present the details of the analog fiber-optic data link that will be used in the chamber-mounted Gamma Reaction History (GRH) diagnostic at the National Ignition Facility (NIF) located at the Lawrence Livermore Laboratory in Livermore, California. The system is based on Mach-Zehnder (MZ) modulators integrated into the diagnostic, with the source lasers and bias control electronics located remotely to protect the active electronics. A complete recording system for a single GRH channel comprises two MZ modulators, with the fiber signals split onto four channels on a single digitizer. By carefully selecting the attenuation, the photoreceiver, and the digitizer settings, the dynamic range achievable is greater than 1000:1 at the full system bandwidth of greater than 10 GHz. The system is designed to minimize electrical reflections and mitigate the effects of transient radiation darkening on the fibers.

[en] Measurements of DT alpha particle loss to the outer midplane region of TFTR have been made using a radially movable scintillator detector. The conclusion from this data is that mechanisms determining the DT alpha loss to the outer midplane are not substantially different from those for DD fusion products. Some of these results are compared with a simplified theoretical model for TF ripple-induced alpha loss, which is expected to be the dominant classical alpha loss mechanism near the outer midplane. An example of plasma-driven MHD-induced alpha particle loss is shown, but no signs of any ''collective'' alpha instability-induced alpha loss have yet been observed

[en] Measurement of alpha particle loss rates to the first wall is of importance in planning tokamak fusion reactors, since large loss rates can adversely affect performance. A set of scintillator-based probes has been operated in TFTR to measure alpha particle losses during its DT campaign. A sample exposure probe has also provided alpha particle loss data under some conditions. These technologies, along with infrared imaging and Faraday cups, may be adaptable to alpha particle loss measurements in ITER or other reactor-scale tokamaks. Constraints on detector operation in a reactor environment are discussed. (orig.)

[en] Alpha particle loss was measured during the TFTR DT experiments with a scintillator detector located at the vessel bottom in the ion ∇B drift direction. The DT alpha particle loss to this detector was consistent with the calculated first orbit loss over the whole range of plasma current I = 0.6-2.7 MA. In particular, the alpha particle loss rate per DT neutron at a given plasma current did not increase significantly with fusion power up to 10.7 MW, indicating the absence of any new 'collective' alpha particle loss processes in these experiments. (author). 36 refs, 25 figs, 2 tabs

[en] Alpha particle loss to the wall of TFTR has been measured during the initial TFTR DT run period. These measurements were made with the same lost alpha scintillator detector system used previously for DD fusion products, except for a switch of the scintillator material from zinc sulfide (P31) to yttrium aluminate (P46) to insure a linear response up to the maximum alpha flux expected in DT. The alpha loss signals in DT are ∼ 100 times larger than the DD fusion product loss signals, as expected from the neutron rates and the relative sensitivity to DT vs. DD fusion products. (author) 10 refs., 4 figs

[en] A strong interaction of fast ions with ion Bernstein waves has been observed in TFTR. It results in a large increase in the fast ion loss rate, and heats the lost particles to several MeV. The lost ions are observed at the passing/trapped boundary and appear to be either DD fusion produced tritons or accelerated D neutral beam ions. Under some conditions, enhanced loss of DT alpha particles is also seen. The losses provide experimental support for some of the elements required for alpha energy channeling

[en] Ion Bernstein waves (IBWS) have been generated by mode conversion of ion cyclotron range of frequency (ICRF) fast waves in TFTR. The loss rate of fusion products in these discharges can be large, up to 10 times the first orbit loss rate. The losses are observed at the passing/trapped boundary, indicating that passing particles are being moved onto loss orbits either by increase of their v perpendicular due to the wave, by outward transport in minor radius, or both. The lost particles appear to be DD fusion produced tritons heated to ∼1.5 times their birth energy