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The ergodic magnetic limiter coils on TEXT have been reconfigured to produce the primary helical perturbation resonance at m = 7 n = 3 . The experiments continue to demonstrate that the weak resonant perturbations modify the edge conditions in keeping with model predictions. We observe a reduction in the intrinsic impurity levels accompanying the helical current pulse, presumably the result of a reduction in the electron temperature in the edge. Heat follows the perturbed field lines to the limiter, generating heat load patterns which reflect the geometry of a magnetic island-limiter intersection. A strong spatial modulation of the electron density in the scrape-off-layer also reflects the helical mode structure.

The Ergodic Magnetic Layer Experiment on ohmically heated Text demonstrates that a small resonant helical field (m/n = 7/2 or 7/3) with fractional amplitude r/BT of about 10−3 creates a stable ergodic magnetic layer and substantially modifies the boundary heat flow. Field line tracings accurately map the observed perturbed limiter heat load patterns. The level of the intrinsic impurities is reduced, consistent with a lower edge electron temperature, as measured by the electron cyclotron emission detector.

The global recombination rate coefficient k/sub r/ for hydrogen has been measured in the TEXT tokamak vacuum vessel for various surface conditions. An attempt was made to correlate the measured values of k/sub r/ with residual gas analyzer (RGA) data taken before each measurement of k/sub r/ and with the power radiated during tokamak discharges produced after each measurement of k/sub r/. The results show that k/sub r/ increases during a series of tokamak discharges, k/sub r/ is relatively insensitive to power radiated during tokamak discharges, and k/sub r/ increases with the RGA measurements of mass 28 and 40 but not with those of mass 18. In addition, it was found that the mass 18 (H/sub 2/O) signal decreases as glow discharge experiments with hydrogen were performed.