2016-11-02T18:49:00

The Ion Cyclotron Emission (ICE) diagnostic on the DIII-D tokamak consists of two outboard midplane systems. In the first system, straps of an ion cyclotron range of frequencies antenna are configured as receiving antennas. For the second system, dedicated magnetic probes incorporated into the outer wall of carbon tiles have recently been restored. These systems collected a large set of radio frequency measurements in the 2015-2018 experimental campaigns by digitizing signals at 200 MSamples/sec for ∼5 seconds per discharge. Each shot typically yields 32 GB of data; techniques for successful handling and analysis of this challengingly large dataset are discussed. The raw voltage fluctuations (<0.2 V and <1 mW) are analyzed in frequency space via fast Fourier transforms. Signals can be analyzed between 1-200 MHz with appropriate filtering and aliasing; this frequency range is limited by DC breaks used to provide 5 kV DC isolation. Three types of high-frequency emission driven by energetic particles have so far been observed using this diagnostic: Compressional Alfvén Eigenmodes with f < 10 MHz, ICE from 5-100 MHz, and whistler waves with f > 100 MHz. ICE occurs at harmonics of the ion cyclotron frequency, enabling the frequency to be mapped to lab space via EFIT equilibrium reconstructions.

No abstract

Beams of neutrinos have been proposed as a vehicle for communications under unusual circumstances, such as direct point-to-point global communication, communication with submarines, secure communications and interstellar communication. We report on the performance of a low-rate communications link established using the NuMI beam line and the MINERvA detector at Fermilab. The link achieved a decoded data rate of 0.1 bits/sec with a bit error rate of 1% over a distance of 1.035 km, including 240 m of earth.

The mechanisms of reciprocating tachyeardias were studied in three patients with WPW syndrome using the catheter technic of His bundle recordings. In the first case it could not be determined with certainty whether the tachycardias involved two anatomically independent fascicles or a single longitudinally dissociated pathway. They were terminated by carotid sinus pressure, which caused A-V nodal block, or by properly timed atrial stimuli, which interrupted the circuit. Short-lived paroxysms of atrial fibrillation in cases 1 and 2 were most probably related to atrial vulnerability. In case 3 there were three types of QRS complexes in lead II representing (a) exclusive His bundle conduction, (b) simultaneous His and Kent bundle conduction, and (c) coexisting His and infra-nodal preferential (Mahaim fiber[?]) conduction. This patient also had three types of reciprocating tachycardias-two of ventricular, and one of atrial origin. The reciprocating circuit probably involved the three pathways. Additional Indexing Words: Mahaim fiber Retrograde conduct S UPRAVENTRICULAR arrhythmias are common in patients with the WPW syndrome.'-3 However, there have been few published reports dealing with the mechanisms of reciprocating tachycardias in this entity.4-'5 It appeared of interest, therefore, to present the tracings of three patients who developed ectopic tachyarrhythmias during the recording of the electrical activity of the specialized conduction system. A careful analysis of these rhythms extends the usefulness of the recently introduced technic of His bundle recordings'6 by increasing our knowledge of basic electrophysiologic phenomena in the human heart.