Publications by Federico David Halpern

DIII-D research towards establishing the scientific basis for future fusion reactors

Wilfred Anthony Cooper, Richard Pitts, Olivier Sauter, Stefan Müller, Mario Ludovico Podesta, Francesca Maria Poli, Dongbin Zhao, Gang Yu, Huan Du, Alessandro Bortolon, Alessandro Marinoni, Jeffrey Huang, Sun Hee Kim, Jérôme Guterl, Zhixian Yan, Fang Liu, Terunobu Akiyama, Xin Yang, Wei Wu, Lorenzo Anton-Louis Talà, Federico David Halpern, Gabriele Merlo, Yu Fu, Shouguo Wang, Sung Chul Park, Xi Chen, Tzu-Hsien Shen, Bingying Zhao, Kyungjin Kim, Ji Hyun Kim, Yi Wang, Hui Wang, Zheng Wang

DIII-D research is addressing critical challenges in preparation for ITER and the next generation of fusion devices through focusing on plasma physics fundamentals that underpin key fusion goals, understanding the interaction of disparate core and boundary ...

IOP Publishing Ltd2019

Poloidal asymmetry in the narrow heat flux feature in the TCV scrape-off layer

Basil Duval, Ivo Furno, Holger Reimerdes, Stefano Coda, Jan Horacek, Benoît Labit, Joaquim Loizu Cisquella, Paolo Ricci, Christian Gabriel Theiler, Federico David Halpern, Federico Nespoli, Cedric Kar-Wai Tsui

Heat flux profiles inferred from a reciprocating probe at the outer midplane of the TCV tokamak during inner wall limited discharges feature radial fall-off lengths that shorten near the last closed flux surface (LCFS) consistent with the so-called narrow ...

American Institute of Physics (AIP)2017

Blob properties in full-turbulence simulations of the TCV scrape-off layer

Ivo Furno, Benoît Labit, Paolo Ricci, Fabio Riva, Federico David Halpern, Fabio Avino, Federico Nespoli

To investigate blob properties in the tokamak scrape-off layer (SOL), we perform dedicated numerical nonlinear simulations of plasma turbulence in the SOL of a TCV discharge using the Global Braginskii Solver code. A blob detection technique is used for th ...

2017

Outer midplane scrape-off layer profiles and turbulence in simulations of Alcator C-Mod inner-wall limited discharges

Federico David Halpern

A region of steep plasma gradients, the so-called "narrow-feature," has been found in the near scrape-off layer (SOL) of inner-wall limited (IWL) discharges. Dedicated IWL discharges were carried out in Alcator C-Mod [Marmar et al., Nucl. Fusion 55, 104020 ...

Amer Inst Physics2017

Scrape-off-layer current loops and floating potential in limited tokamak plasmas

Joaquim Loizu Cisquella, Paolo Ricci, Federico David Halpern, Paola Paruta

We investigate the question of how plasma currents circulate and close in the scrape-off-layer (SOL) of convection-limited tokamak plasmas. A simplified two-fluid model describes how currents must evacuate charge at the sheaths due to cross-field currents ...

Cambridge University Press2017

Non-linear simulations of the TCV Scrape-Off Layer

Ivo Furno, Benoît Labit, Joaquim Loizu Cisquella, Paolo Ricci, Fabio Riva, Federico David Halpern, Federico Nespoli

To investigate the mechanisms leading to the heat deposition onto the first wall in the Scrape-Off Layer (SOL), we perform dedicated numerical non-linear simulations of the SOL plasma dynamics of a TCV discharge using the GBS code. The simulated parallel h ...

Elsevier Science Bv2017

Velocity shear, turbulent saturation, and steep plasma gradients in the scrape-off layer of inner-wall limited tokamaks

Paolo Ricci, Federico David Halpern

The narrow power decay-length (lambda(q)), recently found in the scrape-off layer (SOL) of inner-wall limited (IWL) discharges in tokamaks, is studied using 3D, flux-driven, global two-fluid turbulence simulations. The formation of the steep plasma profile ...

IOP Publishing Ltd2017

The GBS code for tokamak scrape-off layer simulations

Trach-Minh Tran, Sébastien Jolliet, Joaquim Loizu Cisquella, Paolo Ricci, Fabio Riva, Annamaria Mosetto, Federico David Halpern, Christoph Wersal

We describe a new version of GBS, a 3D global, flux-driven plasma turbulence code to simulate the turbulent dynamics in the tokamak scrape-off layer (SOL), superseding the code presented by Ricci et al. (2012) [14]. The present work is driven by the object ...

Elsevier2016

Neoclassical tearing mode seeding by coupling with infernal modes in low-shear tokamaks

Wilfred Anthony Cooper, Jonathan Graves, Federico David Halpern, Daniele Brunetti, Andreas Kleiner

A numerical and an analytical study of the triggering of resistive MHD modes in tokamak plasmas with low magnetic shear core is presented. Flat q profiles give rise to fast growing pressure driven MHD modes, such as infernal modes. It has been shown that i ...

IOP Publishing Ltd2016

A theoretical interpretation of the main scrape-off layer heat-flux width scaling for tokamak inner-wall limited plasmas

Richard Pitts, Jan Horacek, Paolo Ricci, Federico David Halpern

The International Tokamak Physics Activity Topical Group on scrape-off layer and divertor physics has amassed a database comprising hundreds of reciprocating Langmuir probe measurements of the main scrape-off layer heat-flux width lambda(q) in inner-wall l ...

Institute of Physics2016

Plasma turbulence in the scrape-off layer of the ISTTOK tokamak

Paolo Ricci, Federico David Halpern, Rogério Manuel Cabete De Jesus Jorge

The properties of plasma turbulence in a poloidally limited scrape-off layer (SOL) are addressed, with focus on ISTTOK, a large aspect ratio tokamak with a circular cross section. Theoretical investigations based on the drift-reduced Braginskii equations a ...

American Institute of Physics (AIP)2016

The physics of the heat flux narrow decay length in the TCV scrape-off layer: experiments and simulations

Richard Pitts, Ivo Furno, Jan Horacek, Benoît Labit, Paolo Ricci, Christian Gabriel Theiler, Federico David Halpern, Federico Nespoli, Cedric Kar-Wai Tsui

2016

Extended MHD simulations of infernal mode dynamics and coupling to tearing modes

Wilfred Anthony Cooper, Jonathan Graves, Federico David Halpern, Daniele Brunetti

A numerical study of pressure driven magnetohydrodynamic (MHD) instabilities in a low-shear tight aspect ratio configuration is presented. When the magnetic shear is sufficiently small over an extended region in the core, enhanced instability occurs due to ...

Iop Publishing Ltd2015

Approaching the investigation of plasma turbulence through a rigorous verification and validation procedure: A practical examplea)

Ambrogio Fasoli, Ivo Furno, Joaquim Loizu Cisquella, Paolo Ricci, Christian Gabriel Theiler, Fabio Riva, Federico David Halpern

In the present work, a Verification and Validation procedure is presented and applied showing, through a practical example, how it can contribute to advancing our physics understanding of plasma turbulence. Bridging the gap between plasma physics and other ...

American Institute of Physics (AIP)2015

Numerical approach to the parallel gradient operator in tokamak scrape-off layer turbulence simulations and application to the GBS code

Sébastien Jolliet, Joaquim Loizu Cisquella, Paolo Ricci, Fabio Riva, Annamaria Mosetto, Federico David Halpern

This paper presents two discretisation schemes for the parallel gradient operator used in scrape-off layer plasma turbulence simulations. First, a simple model describing the propagation of electrostatic shear-Alfven waves, and retaining the key elements o ...

Elsevier2015

Comparison of 3D flux-driven scrape-off layer turbulence simulations with gas-puff imaging of Alcator C-Mod inner-wall limited discharges

Mario Ludovico Podesta, Paolo Ricci, Federico David Halpern

We carry out a quantitative comparison between gas-puff imaging (GPI) turbulence measurements in Alcator C-Mod inner-wall limited discharges (Zweben et al 2009 Phys. Plasmas 18 082505) and 3D flux-driven drift-reduced Braginskii turbulence simulations of s ...

Iop Publishing Ltd2015

Aspect ratio effects on limited scrape-off layer plasma turbulence

Sébastien Jolliet, Joaquim Loizu Cisquella, Paolo Ricci, Annamaria Mosetto, Federico David Halpern

The drift-reduced Braginskii model describing turbulence in the tokamak scrape-off layer is written for a general magnetic configuration with a limiter. The equilibrium is then specified for a circular concentric magnetic geometry retaining aspect ratio ef ...

American Institute of Physics (AIP)2014

Three-dimensional simulations of blob dynamics in a simple magnetized torus

Sébastien Jolliet, Joaquim Loizu Cisquella, Paolo Ricci, Annamaria Mosetto, Federico David Halpern, Annalisa Cardellini

The propagation of blobs, structures of localized enhanced plasma pressure, is studied in global three-dimensional simulations of a simple magnetized torus. In particular, we carry out single-seeded blob simulations to explore the dependence of the blob ve ...

American Institute of Physics (AIP)2014

Verification methodology for plasma simulations and application to a scrape-off layer turbulence code

Sébastien Jolliet, Joaquim Loizu Cisquella, Paolo Ricci, Fabio Riva, Annamaria Mosetto, Federico David Halpern

Bridging the gap between plasma physics and other scientific domains, in particular, the computational fluid dynamics community, a general, rigorous, and simple-to-apply methodology is presented for both the verification of the correct implementation of th ...

American Institute of Physics2014

Theory of the scrape-off layer width in inner-wall limited tokamak plasmas

Sébastien Jolliet, Joaquim Loizu Cisquella, Paolo Ricci, Annamaria Mosetto, Federico David Halpern

We develop a predictive theory applicable to the scrape-off layer (SOL) of inner-wall limited plasmas. Using the non-linear flattening of the pressure profile as a saturation mechanism for resistive ballooning modes, we are able to demonstrate and quantify ...

International Atomic Energy Agency2014