A novel "Shoelace" antenna has been used to inductively excite a short-wavelength edge fluctuation in a tokamak boundary layer for the first time. The principal design parameters, k ⊥ = 1.5 ± 0.1 cm −1 and 45 < f < 300 kHz, match the Quasi-Coherentfor exhausting impurities in the steady-state, ELM-free Enhanced D α (EDA) Hmode. In H-mode, whether or not there is a QCM, the antenna drives coherent, field-aligned perturbations in density,ñ e , and field,B θ , which are guided by field lines, propagate in the electron diamagnetic drift direction, and exhibit a weaklydamped (γ/ω 0 ∼ 5 − 10%) resonance near the natural QCM frequency. This result is significant, offering the possibility that externally-driven modes may be used to enhance particle transport. In L-mode, the antenna drives only a non-resonantB θ response. The facts that the driven mode has the same wave number and propagation direction as the QCM, and is resonant at the QCM frequency, suggest the antenna may couple to this mode, which we have shown elsewhere to be predominantly driftmode-like (B. LaBombard et al., Phys. Plasmas 2014-accepted).
A newly upgraded correlation electron cyclotron emission (CECE) diagnostic has been installed on the ASDEX Upgrade tokamak and has begun to perform experimental measurements of electron temperature fluctuations. CECE diagnostics measure small amplitude electron temperature fluctuations by correlating closely spaced heterodyne radiometer channels. This upgrade expanded the system from six channels to thirty, allowing simultaneous measurement of fluctuation level radial profiles without repeat discharges, as well as opening up the possibility of measuring radial turbulent correlation lengths. Newly refined statistical techniques have been developed in order to accurately analyze the fluctuation data collected from the CECE system. This paper presents the hardware upgrades for this system and the analysis techniques used to interpret the raw data, as well as measurements of fluctuation spectra and fluctuation level radial profiles.
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