Author: N. N. GorelenkovPublisher:
ISBN:
Category : Magnetohydrodynamic waves
Languages : en
Pages : 0
Book Description
Beam Ion Driven Instabilities in NSTX.
Author: N. N. GorelenkovPublisher:
ISBN:
Category : Magnetohydrodynamic waves
Languages : en
Pages : 0
Book Description
Beam Ion Driven Instabilities in NSTX.
Author: N. N. GorelenkovPublisher:
ISBN:
Category : Magnetohydrodynamic waves
Languages : en
Pages : 8
Book Description
Numerical Study of Instabilities Driven by Energetic Neutral Beam Ions in NSTX.
Author: E. V. BelovaParametric Dependence Of Fast-ion Transport Events On The National Spherical Torus Experiment
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 16
Book Description
Neutral-beam heated tokamak plasmas commonly have more than one third of the plasma kinetic energy in the non-thermal energetic beam ion population. This population of fast ions heats the plasma, provides some of the current drive, and can affect the stability (positively or negatively) of magnetohydrodynamic instabilities. This population of energetic ions is not in thermodynamic equilibrium, thus there is free-energy available to drive instabilities, which may lead to redistribution of the fast ion population. Understanding under what conditions beam-driven instabilities arise, and the extent of the resulting perturbation to the fast ion population, is important for predicting and eventually demonstrating non-inductive current ramp-up and sustainment in NSTX-U, as well as the performance of future fusion plasma experiments such as ITER. This paper presents an empirical approach towards characterizing the stability boundaries for some common energetic-ion-driven instabilities seen on NSTX.
Physics of Intensity Dependent Beam Instabilities
Author: King-Yuen NgPublisher: World Scientific
ISBN: 981270339X
Category : Science
Languages : en
Pages : 795
Book Description
This book provides a comprehensive treatment of intensity dependent particle beam instabilities in accelerating rings. Written for researchers, the material is also suitable for use as a textbook in an advanced graduate course for students studying accelerator physics. The presentation starts with a brief review of the basic concept of wake potentials and coupling impedances in the vacuum chamber followed by a discussion on static and dynamic solutions of their effects on the particle beams. Special emphasis is placed separately on proton and electron machines. Other special topics of interest covered include Landau damping, BalakinOCoNovokhatskyOCoSmirnov damping, Sacherer''s integral equations, Landau cavity, saw-tooth instability, Robinson stability criteria, beam loading, transition crossing, two-stream instabilities, and collective instability issues of isochronous rings. After the formulation of an instability, readers are provided a thorough description of one or more experimental observations together with a discussion of the cures for the instability. Although the book is theory oriented, the use of mathematics has been minimized. The presentation is intended to be rigorous and self-contained with nearly all the formulas and equations derived."
Ion-beam-driven Lower-hybrid Instability and Resultant Anomalous Beam Slowing
Author: Steven W. SeilerNuclear Fusion
Author: MHD Induced Neutral Beam Ion Loss from NSTX Plasmas
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Bursts of ~60 kHz activity on Mirnov coils occur frequently in NSTX plasmas and these are accompanied by bursts of neutral beam ion loss over a range in pitch angles. These losses have been measured with a scintillator type loss probe imaged with a high speed (>10,000 frames/s) video camera, giving the evolution of the energy and pitch angle distributions of the lost neutral beam ions over the course of the events. The instability occurs below the TAE frequency in NSTX (~100 kHz) in high beta plasmas and may be a beta driven Alfvén acoustic (BAAE) mode.
Fast Transverse Beam Instability Caused by Electron Cloud Trapped in Combined Function Magnets
Author: Sergey A. AntipovPublisher: Springer
ISBN: 3030024083
Category : Science
Languages : en
Pages : 95
Book Description
This thesis presents profound insights into the origins and dynamics of beam instabilities using both experimental observations and numerical simulations. When the Recycler Ring, a high-intensity proton beam accelerator at Fermi National Accelerator Laboratory, was commissioned, it became evident that the Recycler beam experiences a very fast instability of unknown nature. This instability was so fast that the existing dampers were ineffective at suppressing it. The nature of this phenomenon, alongside several other poorly understood features of the beam, became one of the biggest puzzles in the accelerator community. The author investigated a hypothesis that the instability arises from an interaction with a dense cloud of electrons accompanying the proton beam. He studied the phenomena experimentally by comparing the dynamics of stable and unstable beams, by numerically simulating the build-up of the electron cloud and its interaction with the beam, and by constructing an analytical model of an electron cloud-driven instability with the electrons trapped in combined-function dipole magnets. He has devised a method to stabilize the beam by a clearing bunch, which conclusively revealed that the instability is caused by the electron cloud, trapped in a strong magnetic field. Finally, he conducted measurements of the microwave propagation through a single dipole magnet. These measurements have confirmed the presence of the electron cloud in combined-function magnets.
Author: J.-S. Kim