Interpretation of fast-ion signals during beam modulation experiments

Heidbrink, W. W.; Collins, C. S.; Stagner, L.; Zhu, Y. B.; Petty, C. C.; Van Zeeland, M. A.

doi:10.1088/0029-5515/56/11/112011

Title: Interpretation of fast-ion signals during beam modulation experiments

Abstract

Fast-ion signals produced by a modulated neutral beam are used to infer fast-ion transport. The measured quantity is the divergence of perturbed fast-ion flux from the phase-space volume measured by the diagnostic, ∇•$$\bar{Γ}$$. Since velocity-space transport often contributes to this divergence, the phase-space sensitivity of the diagnostic (or “weight function”) plays a crucial role in the interpretation of the signal. The source and sink make major contributions to the signal but their effects are accurately modeled by calculations that employ an exponential decay term for the sink. Recommendations for optimal design of a fast-ion transport experiment are given, illustrated by results from DIII-D measurements of fast-ion transport by Alfv´en eigenmodes. Finally, the signal-to-noise ratio of the diagnostic, systematic uncertainties in the modeling of the source and sink, and the non-linearity of the perturbation all contribute to the error in ∇•$$\bar{Γ}$$.

Authors:

Heidbrink, W. W. ^[1]; Collins, C. S. ^[1]; Stagner, L. ^[1]; Zhu, Y. B. ^[1]; Petty, C. C. ^[2]; Van Zeeland, M. A. ^[2]

Univ. of California, Irvine, CA (United States)
General Atomics, San Diego, CA (United States)

Publication Date:: Fri Jul 22 00:00:00 EDT 2016

Research Org.:: Univ. of California, Irvine, CA (United States)

Sponsoring Org.:: USDOE

OSTI Identifier:: 1354784

Alternate Identifier(s):: OSTI ID: 1267535

Grant/Contract Number:: FC02-04ER54698

Resource Type:: Accepted Manuscript

Journal Name:: Nuclear Fusion

Additional Journal Information:: Journal Volume: 56; Journal Issue: 11; Journal ID: ISSN 0029-5515

Publisher:: IOP Science

Country of Publication:: United States

Language:: English

Subject:: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; fast-ions; transport analysis; phase-space transport; perturbative experiments; Alfvén eigenmode instabilities

Citation Formats


                    Heidbrink, W. W., Collins, C. S., Stagner, L., Zhu, Y. B., Petty, C. C., and Van Zeeland, M. A. Interpretation of fast-ion signals during beam modulation experiments.  United States: N. p., 2016. 
Web.  doi:10.1088/0029-5515/56/11/112011.

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                    Heidbrink, W. W., Collins, C. S., Stagner, L., Zhu, Y. B., Petty, C. C., & Van Zeeland, M. A. Interpretation of fast-ion signals during beam modulation experiments.  United States.  https://doi.org/10.1088/0029-5515/56/11/112011

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                    Heidbrink, W. W., Collins, C. S., Stagner, L., Zhu, Y. B., Petty, C. C., and Van Zeeland, M. A. Fri .  
"Interpretation of fast-ion signals during beam modulation experiments".  United States.  https://doi.org/10.1088/0029-5515/56/11/112011.  https://www.osti.gov/servlets/purl/1354784.

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@article{osti_1354784,

  title        = {Interpretation of fast-ion signals during beam modulation experiments},

  author       = {Heidbrink, W. W. and Collins, C. S. and Stagner, L. and Zhu, Y. B. and Petty, C. C. and Van Zeeland, M. A.},

  abstractNote = {Fast-ion signals produced by a modulated neutral beam are used to infer fast-ion transport. The measured quantity is the divergence of perturbed fast-ion flux from the phase-space volume measured by the diagnostic, ∇•$\bar{Γ}$. Since velocity-space transport often contributes to this divergence, the phase-space sensitivity of the diagnostic (or “weight function”) plays a crucial role in the interpretation of the signal. The source and sink make major contributions to the signal but their effects are accurately modeled by calculations that employ an exponential decay term for the sink. Recommendations for optimal design of a fast-ion transport experiment are given, illustrated by results from DIII-D measurements of fast-ion transport by Alfv´en eigenmodes. Finally, the signal-to-noise ratio of the diagnostic, systematic uncertainties in the modeling of the source and sink, and the non-linearity of the perturbation all contribute to the error in ∇•$\bar{Γ}$.},

  doi          = {10.1088/0029-5515/56/11/112011},

  journal      = {Nuclear Fusion},

  number       = 11,

  volume       = 56,

  place        = {United States},

  year         = {Fri Jul 22 00:00:00 EDT 2016},

  month        = {Fri Jul 22 00:00:00 EDT 2016}

}

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Works referenced in this record:

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Dependence of heat pulse propagation on transport mechanisms: Consequences of nonconstant transport coefficients
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Difficulties and solutions for estimating transport by perturbative experiments
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Works referencing / citing this record:

Fast-ion transport by Alfvén eigenmodes above a critical gradient threshold
journal, May 2017

Heidbrink, W. W.; Collins, C. S.; Podestà, M.
Physics of Plasmas, Vol. 24, Issue 5
DOI: 10.1063/1.4977535

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Title: Interpretation of fast-ion signals during beam modulation experiments

Abstract

Citation Formats

Diagnostic applications of transient synchrotron radiation in tokamak plasmas journal, June 1990

Enhancement of the FIDA diagnostic at ASDEX Upgrade for velocity space tomography journal, January 2016

Measurements of the neutron source strength at DIII-D journal, January 1997

The confinement of dilute populations of beam ions in the national spherical torus experiment journal, August 2003

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET journal, November 2014

On velocity space interrogation regions of fast-ion collective Thomson scattering at ITER journal, July 2011

Fusion neutron production during deuterium neutral-beam injection into the PLT tokamak journal, January 1981

On velocity-space sensitivity of fast-ion D-alpha spectroscopy journal, September 2014

Perturbative studies of transport phenomena in fusion devices journal, November 2010

A Code that Simulates Fast-Ion D α and Neutral Particle Measurements journal, September 2011

The tokamak Monte Carlo fast ion module NUBEAM in the National Transport Code Collaboration library journal, June 2004

Fast-ion transport and neutral beam current drive in ASDEX upgrade journal, June 2015

Tomography of fast-ion velocity-space distributions from synthetic CTS and FIDA measurements journal, August 2012

Perturbative transport studies in fusion plasmas journal, August 1995

Extended fast-ion D-alpha diagnostic on DIII-D journal, October 2010

Dependence of heat pulse propagation on transport mechanisms: Consequences of nonconstant transport coefficients journal, January 1988

Electron profile stiffness and critical gradient studies journal, August 2012

Difficulties and solutions for estimating transport by perturbative experiments journal, October 2014

Observation of Critical-Gradient Behavior in Alfvén-Eigenmode-Induced Fast-Ion Transport journal, February 2016

Anomalous Flattening of the Fast-Ion Profile during Alfvén-Eigenmode Activity journal, December 2007

Diagnostic applications of transient synchrotron radiation in tokamak plasmas report, February 1990

Fast-ion transport by Alfvén eigenmodes above a critical gradient threshold journal, May 2017

Diagnostic applications of transient synchrotron radiation in tokamak plasmas
journal, June 1990

Enhancement of the FIDA diagnostic at ASDEX Upgrade for velocity space tomography
journal, January 2016

Measurements of the neutron source strength at DIII-D
journal, January 1997

The confinement of dilute populations of beam ions in the national spherical torus experiment
journal, August 2003

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET
journal, November 2014

On velocity space interrogation regions of fast-ion collective Thomson scattering at ITER
journal, July 2011

Fusion neutron production during deuterium neutral-beam injection into the PLT tokamak
journal, January 1981

On velocity-space sensitivity of fast-ion D-alpha spectroscopy
journal, September 2014

Perturbative studies of transport phenomena in fusion devices
journal, November 2010

A Code that Simulates Fast-Ion D _α and Neutral Particle Measurements
journal, September 2011

The tokamak Monte Carlo fast ion module NUBEAM in the National Transport Code Collaboration library
journal, June 2004

Fast-ion transport and neutral beam current drive in ASDEX upgrade
journal, June 2015

Tomography of fast-ion velocity-space distributions from synthetic CTS and FIDA measurements
journal, August 2012

Perturbative transport studies in fusion plasmas
journal, August 1995

Extended fast-ion D-alpha diagnostic on DIII-D
journal, October 2010

Dependence of heat pulse propagation on transport mechanisms: Consequences of nonconstant transport coefficients
journal, January 1988

Electron profile stiffness and critical gradient studies
journal, August 2012

Difficulties and solutions for estimating transport by perturbative experiments
journal, October 2014

Observation of Critical-Gradient Behavior in Alfvén-Eigenmode-Induced Fast-Ion Transport
journal, February 2016

Anomalous Flattening of the Fast-Ion Profile during Alfvén-Eigenmode Activity
journal, December 2007

Diagnostic applications of transient synchrotron radiation in tokamak plasmas
report, February 1990

Fast-ion transport by Alfvén eigenmodes above a critical gradient threshold
journal, May 2017