Phase Contrast Imaging of Ion Bernstein and Fast Waves in Alcator C-Mod PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Phase Contrast Imaging of Ion Bernstein and Fast Waves in Alcator C-Mod PDF full book. Access full book title Phase Contrast Imaging of Ion Bernstein and Fast Waves in Alcator C-Mod by Eric Alan Nelson-Melby. Download full books in PDF and EPUB format.
Author: Eric Alan Nelson-Melby
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
Get Book Here
Book Description
Direct observation of ICRF (%7E80 MHz) waves (with perpendicular wave numbers from 0.5 cm-1 to 10 cm-1) is now possible in Alcator C-Mod using an optical heterodyne technique on the Phase Contrast Imaging (PCI) system, which uses a CO2 laser to observe electron density fluctuations. The PCI observations are vertical chord averages, so the full-wave ICRF code TORIC [M. Brambilla, Nucl. Fusion 38, 1805-1817 (1998)] has been used to simulate the wave fields in these plasmas to aid interpretation. Mode-converted ion Bernstein waves (IBW) in plasmas composed of H, D and 3He at 6 T have been observed at both high (800 kA) and low (400 kA) current. The fast magnetosonic wave launched from the low-field side has been observed in high density (%7E5 x 1020 m-3) D(H) plasmas with off-axis ICRH at 4.5 T. Comparison between PCI measurements and code results will be presented. Measured wave numbers are in good agreement with the local dispersion relations for both kinds of waves.
Author: Eric Alan Nelson-Melby
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
Get Book Here
Book Description
Direct observation of ICRF (%7E80 MHz) waves (with perpendicular wave numbers from 0.5 cm-1 to 10 cm-1) is now possible in Alcator C-Mod using an optical heterodyne technique on the Phase Contrast Imaging (PCI) system, which uses a CO2 laser to observe electron density fluctuations. The PCI observations are vertical chord averages, so the full-wave ICRF code TORIC [M. Brambilla, Nucl. Fusion 38, 1805-1817 (1998)] has been used to simulate the wave fields in these plasmas to aid interpretation. Mode-converted ion Bernstein waves (IBW) in plasmas composed of H, D and 3He at 6 T have been observed at both high (800 kA) and low (400 kA) current. The fast magnetosonic wave launched from the low-field side has been observed in high density (%7E5 x 1020 m-3) D(H) plasmas with off-axis ICRH at 4.5 T. Comparison between PCI measurements and code results will be presented. Measured wave numbers are in good agreement with the local dispersion relations for both kinds of waves.
Author: Naoto Tsujii
Publisher:
ISBN:
Category :
Languages : en
Pages : 211
Get Book Here
Book Description
Radio frequency (rf) waves in the ion cyclotron range of frequencies (ICRF) are widely used for heating fusion plasmas. In a multi-ion-species plasma, the launched fast waves convert to ion cyclotron waves and ion Bernstein waves in the vicinity of the two-ion hybrid resonance between the cyclotron resonances. The mode converted waves are of interest as actuators to optimize plasma performance through current drive and flow drive. Numerical simulations are essential to describe these processes accurately in a realistic tokamak geometry, and it is important that these simulation codes be validated against experiment. The phase contrast imaging (PCI) technique has been used on Alcator C-Mod to measure directly the rf waves. The measurements were compared to predictions of full-wave simulations using a synthetic diagnostic method. The measured mode converted wave intensity was found to be a factor of ~50 weaker than what was expected from the linear wave theory in a strong mode conversion regime. The agreement improved when the wave intensity was weaker, which is a possible indication of nonlinear wave physics being involved.
Author: Yijun Lin
Publisher:
ISBN:
Category :
Languages : en
Pages : 58
Get Book Here
Book Description
The fast magnetosonic wave (FW), mode converted ion cyclotron wave (MC ICW) and ion Bernstein wave (MC IBW) have all been observed and unambiguously identified in the mode conversion region of Alcator C-Mod. The influences of the species mix, mode conversion location and Bpol=Btot have been studied in D(3He) plasmas at B0 ~ 5:4 T (fRF = 50 MHz) and B0 ~ 8 T (fRF = 78 MHz). The RF waves were measured by a phase contrast imaging (PCI) system. The experimental observation is compared with the result from a synthetic PCI diagnostic based upon the full wave code TORIC. Good agreement between the observation and modeling has been obtained on the spatial structure of the RF waves. When the mode conversion layer was off axis, both MC ICW and MC IBW were observed. In 5.4 T near axis mode conversion discharges, double hump spatial structure of the MC waves was observed experimentally and reproduced by the synthetic PCI. Such structure is an indication of the up-down asymmetry of the MC ICW. In 8 T near axis mode conversion discharges, we had the first definitive observation of IBW dominated MC in Alcator C-Mod.
Author: Yijun Lin
Publisher:
ISBN:
Category :
Languages : en
Pages : 32
Get Book Here
Book Description
Mode conversion (MC) of long wavelength fast electromagnetic (magnetosonic) waves into shorter wavelength electrostatic (ion-Bernstein, or IBW) or the electromagnetic (ion cyclotron, or ICW) waves is of great interest in laboratory, magnetic fusion and space physics experiments. Such processes are particularly important in multi-ion species plasmas. In this paper we report recent results from high power ion cyclotron heating experiments in the Alcator C-Mod tokamak where mode converted waves near the 3He-H hybrid layer have been detected by means of Phase Contrast Imaging (PCI) in H(3He-D) plasmas [E. Nelson-Melby et al, Phys. Rev. Lett. 90, 155004 (2003)]. The measured k-spectrum and spatial location are in agreement with the theoretical predictions[F.W. Perkins, Nucl. Fusion 17, 1197 (1977)] who showed that in a sheared magnetic field, mode-conversion of the magnetosonic wave into ICW may dominate over IBW for appropriate ion species (i.e. D-T, or equivalently, H-3He). Recent modeling with full wave codes, as well as solving the hot plasma dispersion equation in the presence of sheared magnetic fields, verifies the interpretation of such a mode conversion process. Thus, the geometry of the magnetic field, as well as the particular ion species mix, influences the physics of mode conversion processes. In this talk, we also present recent results on the study of mode conversion electron heating (MCEH) in D(H) plasmas [Y. Lin et al., Plasma Phys. Control. Fusion 45 (6), 1013 (2003)]. By comparing the experimentally measured MCEH profile with modeling, the study shows that the MC ICW may make a significant contribution to the direct electron heating when the D-H hybrid layer is off-axis on the high field side. Preliminary results of mode conversion plasma flow drive experiments are also reported.
Author: Y. Nakamura
Publisher: Nova Publishers
ISBN: 9781594544866
Category : Science
Languages : en
Pages : 294
Get Book Here
Book Description
Nuclear fusion is a process in which two nuclei join, forming a larger nucleus and releasing or absorbing energy. With some exceptions, nuclei lighter than iron release energy when they fuse, while heavier nuclei absorb energy; this is because iron has the largest binding energy. Nuclear fusion of light elements is the energy source which causes stars to shine and hydrogen bombs to explode. Nuclear fusion of heavy elements is part of the process that triggers supernovae. Nuclear fusion as an energy source has several advantages: It is vast, new source of energy; Fuels are plentiful; Inherently safe since any malfunction results in a rapid shutdown; No atmospheric pollution leading to acid rain or "greenhouse" effect; Radioactivity of the reactor structure, caused by the neutrons, decays rapidly and can be minimised by careful selection of low-activation materials. Provision for geological time-span disposal is not needed. This book brings together leading research in this field which will play a major role in the 21st century.
Author: Tak K. Mau
Publisher: American Institute of Physics
ISBN:
Category : Medical
Languages : en
Pages : 568
Get Book Here
Book Description
This proceedings volume includes the most recent research advances in the application of RF power in plasmas, mainly in fusion science. Most papers deal with plasma heating and current drive, profile control, and stabilization using RF techniques, with some on RF sources and launchers. New and exciting results from all major tokamak experiments, and from theory and modeling are included. There is also a paper on RFplasma application in space propulsion by an active NASA astronaut. This book is a valuable reference for the RF researchers in fusion and other disciplines.
Author:
Publisher: ScholarlyEditions
ISBN: 1490110437
Category : Science
Languages : en
Pages : 1163
Get Book Here
Book Description
Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2013 Edition is a ScholarlyEditions™ book that delivers timely, authoritative, and comprehensive information about High Energy Physics. The editors have built Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about High Energy Physics in this book to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2013 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309109434
Category : Science
Languages : en
Pages : 281
Get Book Here
Book Description
As part of its current physics decadal survey, Physics 2010, the NRC was asked by the DOE, NSF, and NASA to carry out an assessment of and outlook for the broad field of plasma science and engineering over the next several years. The study was to focus on progress in plasma research, identify the most compelling new scientific opportunities, evaluate prospects for broader application of plasmas, and offer guidance to realize these opportunities. The study paid particular attention to these last two points. This "demand-side" perspective provided a clear look at what plasma research can do to help achieve national goals of fusion energy, economic competitiveness, and nuclear weapons stockpile stewardship. The report provides an examination of the broad themes that frame plasma research: low-temperature plasma science and engineering; plasma physics at high energy density; plasma science of magnetic fusion; space and astrophysical science; and basic plasma science. Within those themes, the report offers a bold vision for future developments in plasma science.
Author: Cary B. Forest
Publisher: American Institute of Physics
ISBN:
Category : Science
Languages : en
Pages : 544
Get Book Here
Book Description
Includes the most recent research advances in the application of RF power in plasmas, mainly in fusion science.
Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 1396
Get Book Here
Book Description
