다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

1 The Equations of Gas Dynamics 2 Magnetoplasma Dynamics 3 Waves in Magnetoplasmas 4 Magnetoplasma Stability 5 Transport in Magnetoplasmas 6 Extensions of Theory Bibliography Index

Physics of plasmas

The advantages of nuclear fusion as an energy source and research progress in this area are summarized. The current state of the art is described. Laser fusion, inertial confinement fusion, and magnetic fusion (the tokamak) are explained, the latter in some detail. Remaining problems and planned future reactors are considered. They are the Compact Ignition Tokamak (CIT), the International Thermonuclear Experimental Reactor (ITER), and a US design called TIBER II. The design of the latter is shown. >

http://ieeexplore.ieee.org/iel1/45/1370/00031587.pdf

Nuclear fusion

The use of the compressional hydromagnetic mode (also called the magnetosonic or, simply, the fast wave) is examined in some detail with respect to the heating of a tritium plasma containing a few percent deuterium. Efficient absorption of wave energy by the deuteron component is found when ω = ωC (deuterons), with Qwave 100. Reasonable efficiencies are found also for electron heating, but coherence effects between transit-time and Landau damping for electrons reduce the total absorption for both processes to one-half of the transit-time power, calculated separately.The fusion output of a two-component neutral-injected plasma can be enhanced by selective heating of the injected deuterons. Also, selective deuteron absorption may be used for ion-tail creation by radiofrequency excitation alone, as an alternative to neutral injection. The dominant behaviour of the high-energy deuteron distribution function is found to be f(v) ~ exp[(3/2)∫vdv / ], where is the Chandrasekhar-Spitzer drag coefficient, and is the Kennel-Engelmann quasi-linear diffusion coefficient for wave-particle interaction at the deuteron cyclotron frequency. An analytic solution to the one-dimensional Fokker-Planck equation, with r.f.-induced diffusion, is developed, and using this solution together with Duane's fit to the D-T fusion cross-section, it is found that the nuclear-fusion power output from an r.f.-produced two-component plasma can significantly exceed the incremental (radiofrequency) power input.

Fast-wave heating of a two-component plasma

Transport Processes in the Plasma

Since 2011 JET is equipped with a Beryllium ”ITER-like” wall (ILW) and a Tungsten divertor [1]. As it can lead to reduced core temperature and even radiative collapse, high Z core impurity accumulation has to be avoided. Hydrogen minority ion cyclotron heating at sufficiently high power (> 4MW in JET) is already well known to be an effective cure for this problem [2, 3, 4, 5, 6, 7]. In the context of exploring the available options for a D − T campaign but without actually using T , this paper reports on investigations checking if D majority ion cyclotron resonance heating (ICRH) scenarios exist that can simultaneously ensure a high ion heating efficiency needed for reaching fusion relevant temperatures and impurity chase-out.

Recent Ion Cyclotron Resonance Heating Experiments in JET in Preparation of a DT Campaign

JETにおける高速イオンD-D及びD- 3 He核融合を通じた核融合生成物研究

A commercial fusion power plant will need tritium breeding to provide its fuel. Tritium is expected to be bred from lithium blankets, and one of the key things to demonstrate in ITER is the successful breeding of tritium during the fusion burn. To this end, ITER is equipped with three test blanket modules (TBM) that are placed very close to the plasma to maximize neutron irradiation. The massive modules are made of demo relevant ferromagnetic martensitic steel and will thus produce a field of their own that perturbs the nominal field produced by the TF and PF coils as well as the plasma current. Collisionless particles, such as alpha particles born in fusion reactions, are particularly sensitive to field perturbations, and if their confinement is significantly compromised, the integrity of the first wall could be jeopardized. For these reasons it is very important to carefully calculate the perturbations introduced by various ferromagnetic components in ITER, and use the resulting total field to assess the confinement of fusion alphas. In this contribution we report on the magnetic field structure and wall power loads in the ITER 15MA scenario when both the European TBM design and the ferritic inserts (FIs) are included in the calculation at varying degree of detail. As a reference, we shall use the ITER nominal field where ripple mitigation by the FIs inside the ITER double wall structure is not included. In addition, also the effect of the ELM coils (ECs) on the field structure and on fusion alpha confinement is addressed.

ITER fusion alpha particle confinement in the presence of the European TBMs and ELM coils

T. Koskela1, O. Asunta1, G.J. Kramer2, T. Kurki-Suonio1, A. Salmi1, M. Schaffer3, T. Tala4 and the DIII-D experimental team 1 Aalto Univeristy, Association Euratom-Tekes, P.O. Box 15100 FI-00076 AALTO, Finland 2 Plasma Physics Laboratory, Princeton University, P.O.Box 451, Princeton, NJ, 08543 3 General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA 4 VTT, Association Euratom-Tekes, P.O. Box 1000 FI01044 VTT, Finland

/pdf/ascot-modeling-of-fast-ion-losses-in-diii-d-tbm-experiments-128h9dhp6u.pdf

ASCOT modeling of fast ion losses in DIII-D TBM experiments

In this session we show, in two case studies, how the roofline feature of Intel Advisor has been utilized to optimize the performance of kernels of the XGC1 and PICSAR codes in preparation for Intel Knights Landing architecture. The impact of the implemented optimizations and the benefits of using the automatic roofline feature of Intel Advisor to study performance of large applications will be presented. This demonstrates an effective optimization strategy that has enabled these science applications to achieve up to 4.6 times speed-up and prepare for future exascale architectures. # Goal/Relevance of Session The roofline model [1,2] is a powerful tool for analyzing the performance of applications with respect to the theoretical peak achievable on a given computer architecture. It allows one to graphically represent the performance of an application in terms of operational intensity, i.e. the ratio of flops performed and bytes moved from memory in order to guide optimization efforts. Given the scale and complexity of modern science applications, it can often be a tedious task for the user to perform the analysis on the level of functions or loops to identify where performance gains can be made. With new Intel tools, it is now possible to automate this task, as well as base the estimates of peak performance on measurements rather than vendor specifications. The goal of this session is to demonstrate how the roofline feature of Intel Advisor can be used to balance memory vs. computation related optimization efforts and effectively identify performance bottlenecks. A series of typical optimization techniques: cache blocking, structure refactoring, data alignment, and vectorization illustrated by the kernel cases will be addressed. # Description of the codes ## XGC1 The XGC1 code [3] is a magnetic fusion Particle-In-Cell code that uses an unstructured mesh for its Poisson solver that allows it to accurately resolve the edge plasma of a magnetic fusion device. After recent optimizations to its collision kernel [4], most of the computing time is spent in the electron push (pushe) kernel, where these optimization efforts have been focused. The kernel code scaled well with MPI+OpenMP but had almost no automatic compiler vectorization, in part due to indirect memory addresses and in part due to low trip counts of low-level loops that would be candidates for vectorization. Particle blocking and sorting have been implemented to increase trip counts of low-level loops and improve memory locality, and OpenMP directives have been added to vectorize compute-intensive loops that were identified by Advisor. The optimizations have improved the performance of the pushe kernel 2x on Haswell processors and 1.7x on KNL. The KNL node-for-node performance has been brought to within 30% of a NERSC Cori phase I Haswell node and we expect to bridge this gap by reducing the memory footprint of compute intensive routines to improve cache reuse. ## PICSAR is a Fortran/Python high-performance Particle-In-Cell library targeting at MIC architectures first designed to be coupled with the PIC code WARP for the simulation of laser-matter interaction and particle accelerators. PICSAR also contains a FORTRAN stand-alone kernel for performance studies and benchmarks. A MPI domain decomposition is used between NUMA domains and a tile decomposition (cache-blocking) handled by OpenMP has been added for shared-memory parallelism and better cache management. The so-called current deposition and field gathering steps that compose the PIC time loop constitute major hotspots that have been rewritten to enable more efficient vectorization. Particle communications between tiles and MPI domain has been merged and parallelized. All considered, these improvements provide speedups of 3.1 for order 1 and 4.6 for order 3 interpolation shape factors on KNL configured in SNC4 quadrant flat mode. Performance is similar between a node of cori phase 1 and KNL at order 1 and better on KNL by a factor 1.6 at order 3 with the considered test case (homogeneous thermal plasma).

Tuomas Koskela

Papers

Recent Ion Cyclotron Resonance Heating Experiments in JET in Preparation of a DT Campaign

JETにおける高速イオンD-D及びD- 3 He核融合を通じた核融合生成物研究

ITER fusion alpha particle confinement in the presence of the European TBMs and ELM coils

ASCOT modeling of fast ion losses in DIII-D TBM experiments

Roofline Analysis in the Intel® Advisor to Deliver Optimized Performance for applications on Intel® Xeon Phi™ Processor