skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Fast ion transport in the quasi-single helical reversed-field pinch

Journal Article · · Physics of Plasmas
DOI:https://doi.org/10.1063/1.5084059· OSTI ID:1648958

The reversed-field pinch (RFP) can spontaneously transition from an axisymmetric magnetic topology to a 3D-helical geometry. Investigations on fast ion transport associated with energetic particle driven Alfvén instabilities, tearing mode induced stochasticity, and neoclassical effects have been performed on the Madison Symmetric Torus. STELLGAP produced shear-Alfvén continua seeded with V3FIT 3D-equilibrium reconstructions describe the response of Alfvénic bursting activity as a direct consequence of the equilibrium change on the fast ion resonance. Furthermore, far infrared interferometry resolved electron density perturbations associated with the bursts provide a spatial measurement of the mode structure and support the reconstructions. The bursts produce no global resonant fast ion transport; however, their disappearance at a high core-resonant amplitude implies other transport mechanisms at play. Additionally, neutral particle analysis and neutron signals suggest fast ion losses at sufficient core tearing mode strength, supporting the lack of Alfvénic activity. The guiding-center code ORBIT corroborates rapid fast ion loss times in the helical state largely as a consequence of remnant tearing modes. Additionally, ORBIT simulations demonstrate little neoclassical enhancement of particle transport. While superbanana orbits may exist, the growth in the core-resonant fast ion island and the associated secondary mode overlap govern the largest transport process, leading to robust fast ion losses in the 3D-RFP.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Grant/Contract Number:
AC05-00OR22725; FC02-05ER54814
OSTI ID:
1648958
Alternate ID(s):
OSTI ID: 1511780
Journal Information:
Physics of Plasmas, Vol. 26, Issue 2; ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 9 works
Citation information provided by
Web of Science

References (36)

3D toroidal physics: Testing the boundaries of symmetry breakinga) journal May 2015
Three dimensional equilibrium solutions for a current-carrying reversed-field pinch plasma with a close-fitting conducting shell journal March 2016
Fast-Particle-Driven Alfvénic Modes in a Reversed Field Pinch journal September 2012
Control of 3D equilibria with resonant magnetic perturbations in MST journal September 2015
Transport in non-axisymmetric tori with up-down asymmetry journal September 1993
Hamiltonian guiding center drift orbit calculation for plasmas of arbitrary cross section journal January 1984
Self-organized helical equilibria as a new paradigm for ohmically heated fusion plasmas journal June 2009
Study of stochastic toroidal field ripple losses of charged fusion products at the midplane of TFTR journal March 1993
Experimental scaling of fluctuations and confinement with Lundquist number in the reversed-field pinch journal April 1998
Omnigenity and quasihelicity in helical plasma confinement systems journal September 1997
Superbanana Orbits in Stellarator Geometries journal December 1979
Omnigenity as generalized quasisymmetry journal May 2012
Observation of Weak Impact of a Stochastic Magnetic Field on Fast-Ion Confinement journal September 2005
Measurement of energetic-particle-driven core magnetic fluctuations and induced fast-ion transport journal March 2013
Three-dimensional effects on energetic particle confinement and stability journal May 2011
The behaviour of fast ions in tokamak experiments journal April 1994
Neoclassical Transport in the Helical Reversed-Field Pinch journal November 2010
Comparison of experimental and theoretical fast ion slowing-down times in DIII-D journal October 1988
Single-Helical-Axis States in Reversed-Field-Pinch Plasmas journal July 2008
Experimental Demonstration of Improved Neoclassical Transport with Quasihelical Symmetry journal February 2007
Reduced particle and heat transport with quasisymmetry in the Helically Symmetric Experiment journal May 2007
The behaviour of fast ions in tokamak experiments journal February 1995
Ripple‐induced energetic particle loss in tokamaks journal August 1996
Basic physics of Alfvén instabilities driven by energetic particles in toroidally confined plasmas journal May 2008
Fast ion confinement in the three-dimensional helical reversed-field pinch journal August 2014
Particle-Transport Analysis in Reversed Field Pinch Helical States journal September 2004
Vanishing Magnetic Shear And Electron Transport Barriers In The RFX-Mod Reversed Field Pinch journal January 2011
Shear Alfvén continua in stellarators journal August 2003
Energetic particle transport in compact quasi-axisymmetric stellarators journal September 1999
Internal Transport Barrier Broadening through Subdominant Mode Stabilization in Reversed Field Pinch Plasmas journal May 2016
Energetic-particle-driven instabilities and induced fast-ion transport in a reversed field pinch journal May 2014
Effect of resonant magnetic perturbations on three dimensional equilibria in the Madison Symmetric Torus reversed-field pinch journal March 2016
Study of the scaling of magnetic fluctuations in the RFX reversed field pinch 1 journal June 2000
V3FIT: a code for three-dimensional equilibrium reconstruction journal July 2009
Class of Model Stellarator Fields with Enhanced Confinement journal February 1982
Transport optimization in stellarators journal May 2006

Cited By (3)

Fast Ion Transport in the Three-Dimensional Reversed-Field Pinch journal July 2019
Shear Alfvén wave continuum spectrum with bifurcated helical core equilibria journal September 2019
A measure of fast ion beta at marginal stability in the reversed field pinch journal June 2019

Similar Records

Using neutral beams as a light ion beam probe (invited)
Journal Article · Tue Aug 05 00:00:00 EDT 2014 · Review of Scientific Instruments · OSTI ID:1648958

Overview of results from the MST reversed field pinch experiment
Journal Article · Fri Mar 27 00:00:00 EDT 2015 · Nuclear Fusion · OSTI ID:1648958

Using neutral beams as a light ion beam probe (invited)
Journal Article · Sat Nov 15 00:00:00 EST 2014 · Review of Scientific Instruments · OSTI ID:1648958