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What’s the most difficult question you’ve been asked as a maintenance instructor?
Blye Widmar
"Where are the prints?!"
This was the final question in an onslaught of verbal feedback, comments, and critiques I received from my students back in 2019. I had two years of instructor experience and was teaching a class that had been meticulously rehearsed in preparation for an accreditation visit. I knew the training material well and transferred that knowledge effectively enough for all the students to pass the class. As we wrapped up, I asked the students how they felt about my first big system-level class, and they did not hold back.
“Why was the exam from memory when we don’t work from memory in the plant?” “Why didn’t we refer to the vendor documents?” “Why didn’t we practice more on the mock-up?” And so on.
K. Ida, M. Yoshinuma, K. Tanaka, R. Sakamoto, S. Inagaki, LHD Experiment Group
Fusion Science and Technology | Volume 58 | Number 1 | July-August 2010 | Pages 150-159
Chapter 3. Confinement and Transport | Special Issue on Large Helical Device (LHD) | doi.org/10.13182/FST10-A10802
Articles are hosted by Taylor and Francis Online.
The interlinkage of particle, momentum, and heat transport in plasmas appears as a nondiffusive term of each transport equation. The physical mechanisms determining the diffusive and nondiffusive terms of particle, momentum, and heat transports are described. The nondiffusive term in the particle transport and impurity transport, which causes an inward pinch or outward flux, is driven by the temperature gradient and the magnetic field curvature. One significant piece of evidence of the nondiffusive term of particle transport is observed in the impurity transport as an impurity hole, where the impurity profiles become extremely hollow and the inward flow due to the density gradient is balanced with the outward flow driven by the ion temperature gradients. The outward convection of impurity observed contradicts the neoclassical prediction but is expected to contribute to the purity of plasma in the ion root even if the radial electric field is negative. The nondiffusive term in the momentum transport, which drives spontaneous toroidal rotation, is also observed in the plasmas in the Large Helical Device (LHD). The spontaneous rotations are driven by the electric field near the plasma edge and the ion temperature gradient at the midradius in the plasma. In the heat transport, no clear nondiffusive term is observed, and it is considered to be diffusive. The temperature and temperature gradient dependences of the diffusive terms are studied with the perturbation transport study and the slow transition between two transport branches that have a weak and a strong temperature dependence of thermal diffusivity.