444 research outputs found
Analysis of D Pellet Injection Experiments in the W7-AS Stellarator
A centrifugal injector was used to inject deuterium pellets (with 3--5 x 10{sup 19} atoms) at approx. equal 600 m/s into current-less, nearly shear-less plasmas in the Wendelstein 7-AS (W7-AS) stellarator. The D pellet was injected horizontally at a location where the non-circular and non-axisymmetric plasma cross section is nearly triangular. Visible-light TV pictures usually showed the pellet as a single ablating mass in the plasma, although the pellet occasionally broke in two or splintered into a cloud of small particles. The density evolution following pellet injection and the effect of pellet injection on energy confinement and fluctuations are discussed
A Delayed Choice Quantum Eraser
This paper reports a "delayed choice quantum eraser" experiment proposed by
Scully and Dr\"{u}hl in 1982. The experimental results demonstrated the
possibility of simultaneously observing both particle-like and wave-like
behavior of a quantum via quantum entanglement. The which-path or both-path
information of a quantum can be erased or marked by its entangled twin even
after the registration of the quantum.Comment: twocolumn, 4pages, submitted to PR
Major results from the first plasma campaign of the Wendelstein 7-X stellarator
After completing the main construction phase of Wendelstein 7-X (W7-X) and successfully
commissioning the device, first plasma operation started at the end of 2015. Integral
commissioning of plasma start-up and operation using electron cyclotron resonance heating
(ECRH) and an extensive set of plasma diagnostics have been completed, allowing initial
physics studies during the first operational campaign. Both in helium and hydrogen, plasma
breakdown was easily achieved. Gaining experience with plasma vessel conditioning,
discharge lengths could be extended gradually. Eventually, discharges lasted up to 6 s,
reaching an injected energy of 4 MJ, which is twice the limit originally agreed for the limiter
configuration employed during the first operational campaign. At power levels of 4 MW
central electron densities reached 3 × 1019 m−3
, central electron temperatures reached values
of 7 keV and ion temperatures reached just above 2 keV. Important physics studies during this
first operational phase include a first assessment of power balance and energy confinement,
ECRH power deposition experiments, 2nd harmonic O-mode ECRH using multi-pass
absorption, and current drive experiments using electron cyclotron current drive. As in many
plasma discharges the electron temperature exceeds the ion temperature significantly, these
plasmas are governed by core electron root confinement showing a strong positive electric
field in the plasma centre.EURATOM 63305
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