**Brian LaBombard**

** Senior Research Scientist**

*Reasearch Topics*

*Research Interests*

Brian has been a leader in the area of experimental plasma boundary and divertor physics in magnetic fusion devices since joining that nascent field as a graduate student in 1978. Boundary plasma physics plays a critical role in the performance of magnetic fusion devices – setting the power and particle flux densities to first wall surfaces, determining impurity levels in the plasma core, imposing boundary conditions for plasma flow and rotation, and participating in the formation of edge transport barriers, all of which ultimately determine the level of plasma energy confinement.

The scientific feasibility of energy production from plasma fusion will soon be demonstrated in ITER, yielding 10 times more power out than in. Yet, much more research is needed to identify robust solutions to power exhaust and plasma-material interaction challenges for electricity-producing fusion reactors. Ultimately, the success of these devices will come from assembling the knowledge base, developing the first-principles understanding and demonstrating the means to control boundary plasma phenomena.

*Education*

MIT, Cambridge, Massachusetts, Sc.D. (1986) Nuclear Engineering, Applied Plasma Physics

U. Lowell, Lowell, Massachusetts, B.S.,*summa cum laude* (1978) Nuclear Engineering

U. Lowell, Lowell, Massachusetts, B.S.,

*Biographical Sketch*

Brian began his plasma studies as an MIT doctoral student on the Alcator A and C tokamaks. Building a unique array of Langmuir probes, he performed experiments that revealed edge plasma conditions with unprecedented detail and uncovered key information on poloidal transport asymmetries and MARFE phenomena. In 1986, Dr. LaBombard joined the PISCES plasma-material facility at UCLA. As co-principal investigator, he initiated basic plasma physics experiments on PISCES-A and CCT (Continuous Current Tokamak) and was a project leader for construction of the PISCES-B facility. Dr. LaBombard joined Alcator C-Mod in 1988 at the start of its construction phase and, with the help of students, led the assembly of an extensive set of edge diagnostics for C-Mod. In support of the broader magnetic fusion science program, Brian also makes key contributions in the design/engineering of first-wall and divertor components.

Brian has made seminal contributions to boundary plasma physics: uncovering ‘main-chamber recycling’ phenomenon in C-Mod’s diverted plasmas and revealing intermittent, non-diffusive transport in the scrape-off layer as the underlying cause; identifying edge plasma transport and its scaling with collisionality as a key physics ingredient in the empirical tokamak density limit; demonstrating that ballooning-like transport asymmetries drive near-sonic parallel plasma flows in the plasma edge and that such transport-driven flows impose a toroidal rotation boundary condition for the confined plasma; uncovering evidence that pressure gradients are constrained near the last-closed flux surface, being clamped at a ‘critical value’ that scales with poloidal magnetic field squared and varies with plasma collisionality. These observations broadly connect with results from state-of-the-art numerical simulations of electromagnetic plasma turbulence, pointing toward a first-principles understanding of the underlying transport physics, including the physics of the tokamak density limit. Two of Brian's first-authored papers [Nuclear Fusion 44 (2004) 1047 and Nuclear Fusion 45 (2005) 1658] were nominated for the 2007 and 2008 Nuclear Fusion awards – one of the ten “very best papers published” in 2004 and 2005, respectively.

Brian is a fellow of the American Physical Society, a key contributor to the ITER physics basis and a research supervisor for graduate and undergraduate students. He has served as external examiner for numerous graduate theses and mentor for the national undergraduate fellowship program in fusion.

Brian has made seminal contributions to boundary plasma physics: uncovering ‘main-chamber recycling’ phenomenon in C-Mod’s diverted plasmas and revealing intermittent, non-diffusive transport in the scrape-off layer as the underlying cause; identifying edge plasma transport and its scaling with collisionality as a key physics ingredient in the empirical tokamak density limit; demonstrating that ballooning-like transport asymmetries drive near-sonic parallel plasma flows in the plasma edge and that such transport-driven flows impose a toroidal rotation boundary condition for the confined plasma; uncovering evidence that pressure gradients are constrained near the last-closed flux surface, being clamped at a ‘critical value’ that scales with poloidal magnetic field squared and varies with plasma collisionality. These observations broadly connect with results from state-of-the-art numerical simulations of electromagnetic plasma turbulence, pointing toward a first-principles understanding of the underlying transport physics, including the physics of the tokamak density limit. Two of Brian's first-authored papers [Nuclear Fusion 44 (2004) 1047 and Nuclear Fusion 45 (2005) 1658] were nominated for the 2007 and 2008 Nuclear Fusion awards – one of the ten “very best papers published” in 2004 and 2005, respectively.

Brian is a fellow of the American Physical Society, a key contributor to the ITER physics basis and a research supervisor for graduate and undergraduate students. He has served as external examiner for numerous graduate theses and mentor for the national undergraduate fellowship program in fusion.

"ADX: A concept for a high-power density, advanced divertor tokamak test experiment"

PPPL Seminar, May12, 2014

"Heat and particle exhaust in tokamak reactors: challenges and potential solutions"

PSFC Seminar, Dec. 20, 2013

APS 2013, Denver, CO: "Critical need for MFE: the Alcator DX high power divertor test facility"

Poster

MIT Energy Night 2013: "Alcator DX: a high power density experimental facility to advance the development of magnetic fusion energy"

Poster

Presentation to DoE at Alcator C-Mod Quarterly Revew, March 7, 2013

Alcator_DX: Oral Presentation

White Paper submitted to FESAC subcommittee on future facilities, Feb. 14, 2013

Alcator_DX: High Power Density Advanced Divertor Test Facility

*X-point Target Divertor in Alcator DX*

APS 2013, Denver, CO: "X-point target divertor concept and the Alcator DX high power divertor test facility"

Oral Presentation

Presentation at MIT PSFC, Feb. 4, 2013

X-point Target Divertor Concept

APS 2013, Denver, CO: "New insights on boundary plasma turbulence and the Quasi-Coherent Mode in Alcator C-Mod using a Mirror Langmuir Probe"

The QCM is unambiguously identified as an electron drift-wave with significant interchange drive and EM contributions.

Invited Talk

Press Release

D Brunner et al Plasma Phys. Control. Fusion 55 095010 (2013).

TTF2013, Santa Rosa, CA: "Mirror Langmuir Probe observations of edge plasma turbulence and the Quasi-Coherent Mode in Alcator C-Mod"

Oral Presentation

Poster Presentation

Transport and drift-driven plasma flow components in the Alcator C-Mod boundary plasma

N. Smick, Nuclear Fusion 53 (2013) 023001

Divertor ‘death-ray’ explained: An artifact of a Langmuir probe operating at negative bias in a high-recycling divertor

D. Brunner, J. Nucl. Mater. 2013

APS 2012, Providence, RI: "Mirror Langmuir Probe measurements of fluctuation-induced heat and particle transport in the Alcator C-Mod boundary plasma

Oral Presentation

APS 2011, Salt Lake City, UT: "Shoelace' Antenna System for Direct Excitation of C-Mod's Quasi-Coherent Mode (QCM) and Boundary Layer Turbulence"

Poster_Presentation

APS 2010, Chicago, IL - Scaling of the power exhaust channel in Alcator C-Mod

Invited Paper, Phys. Plasmas 18 (2011) 056104

APS 2010, Chicago, IL - Scaling of the power exhaust channel in Alcator C-Mod

Invited Talk

Press Release from APS Meeting

Joint Research Target - Heat flux 'footprints' in the boundary plasmas of Alcator C-Mod, DIII-D and NSTX

FY2010 Annual Performance Target Final Report

Boundary Layer Heat Transport Experiments in Alcator C-Mod in Support of the FY2010 US DoE Joint Research Target

PSFC Internal Report

PSI 2010, San Diego, CA - Divertor heat flux footprints in EDA H-mode discharges on Alcator C-Mod

Poster Presentation

Paper (published in J. Nucl. Mater.)

APS 2008, Dallas, TX - Relationship between Edge Gradients and Plasma Flows in Alcator C-Mod

Contributed Oral

TTF 2008, Boulder, CO - Scrape-off layer flows, toroidal rotation and critical gradient phenomena in the tokamak edge

Plenary Invited Talk

APS 2007, Orlando, FL - Critical gradients and plasma flows in the edge of Alcator C-Mod

Invited Paper, Phys. Plasmas 15 (2008) 056106.

APS 2007, Orlando, FL - Critical gradients and plasma flows in the edge of Alcator C-Mod

Invited Talk

Press Release from APS Meeting

APS 2006, Philadelphia, PA - Critical edge gradients and flows with reversed magnetic field in Alcator C-Mod

Contributed Oral

PSI 2006, Hefei, Anhui, China - Operational Phase Space of the Edge Plasma and Its Sensitivity to Magnetic Topology in Alcator C-Mod

Contributed Talk

Paper - J, Nucl. Mater. 363-365 (2007) 517.

Edge and Pedestal Physics ITPA Group Meeting at MIT, April 10-12, 2006 - Plasma flows and critical gradient phenomena near the last-closed flux surface

Workshop Talk

APS 2005, Denver, CO - Operational Phase Space of the Edge Plasma in Alcator C-Mod

Contributed Oral

Evidence for electromagnetic fluid drift turbulence controlling the edge plasma state in the Alcator C-Mod tokamak

Nuclear Fusion 45 (2005) 1658

EPS 2005, Tarragona, Spain - Transport-driven scrape-off layer flows and the role of the x-point

Invited Talk

Sherwood 2005, Stateline, Nevada - Scrape-off layer flows, magnetic topology, and the boundary conditions imposed at the separatrix in a tokamak plasma

Review Talk

APS 2004, Savannah, GA - Transport-driven scrape-off layer flows and the x-point dependence of the L-H power threshold in Alcator C-Mod

Invited Talk

Press Release from APS Meeting

APS 2004, Savannah, GA - Transport-driven scrape-off layer flows and the x-point dependence of the L-H power threshold in Alcator C-Mod

Invited Paper, Phys. Plasmas 12 (2005) 056111

PSI 2004, Portland, ME - Poloidal Transport Asymmetries, Edge Plasma Flows and Toroidal Rotation in Alcator C-Mod

Invited Talk

PSI 2004, Portland, ME - Plasma Profiles and Flows in the High-Field Side Scrape-off Layer in Alcator C-Mod

Contributed Poster

Transport-Driven Scrape-off Layer Flows and the Boundary Conditions Imposed at the Magnetic Separatrix in a Tokamak Plasma

Nucl. Fusion 44 (2004) 1047 (http://www.psfc.mit.edu/library/04ja/04JA017/04JA017_abs.html)

Scrape-off layer flows, magnetic topology and influence on the L-H threshold in a tokamak

Submitted to PRL January 21, 2004, rejected by PRL June 2, 2004 (http://www.psfc.mit.edu/library/04ja/04JA016/04JA016_abs.html)

ITERPhysics Basis Contribution - Cross-field Particle Transportin the Edge Plasma of Tokamak Experiments and Implications for ITER Operation

Report (http://www.psfc.mit.edu/library/03rr/03RR008/03RR008_abs.html)

APS 2003, Albuquerque, NM - Evidence for Electromagnetic Fluid Drift Turbulence Controlling the Edge Plasma State in Alcator C-Mod

Contributed Oral

APS 2003, Albuquerque, NM - Plasma Profiles and Flows in the High-Field Scrape-off Layer in Alcator C-Mod

Contributed Poster

In-Situ Gas Conductance and Flow Measurements Through Alcator C-Mod Divertor Structures With and Without Plasma Present

Report (http://www.psfc.mit.edu/library/03rr/03RR006/03RR006_abs.html)

IAEA2002, Lyon, France - Density Limit and Cross-Field Edge Transport Scaling in Alcator C-Mod

Talk - short version

Talk - full version

Paper (also see: http://www.iaea.org/programmes/ripc/physics/fec2002/html/fec2002.htm)

PSI 2002,Gifu, Japan - Toroidal rotation as an explanation for plasmaflow observations in the Alcator C-Mod scrape-off layer

Poster Presentation

Paper (published in J. Nucl. Mater.)

Analysis of fluctuation-driven particle fluxes measured by probes

Paper - Physics of Plasmas 9 (2002)

APS 2001, Long Beach, CA - Phenomenology and Scaling of Cross-Field Plasma Transport in the Alcator C-Mod Edge Plasma

Contributed poster

IAEATechnical Committee Meeting on DIVERTOR CONCEPTS September 11-14,2001, Aix-en-Provence, France: - Cross-field Plasma Transport inthe Scrape-off Layer: A key physics issue for SOL, divertor and coreplasma

Invited_Review Talk

Plasma Fluctuations in the 'Far SOL'

Paper - Physics of Plasmas 8 (2001) 3702

Workshop on Plasma Turbulence and Transport in Edge/SOL Regions 14-15 May, 2001, Fairbanks, Alaska - Particle Transport in the Alcator C-ModScrape-off Layer

Talk

APS 2000, Quebec City, Canada - Particle transport in the scrape-off layer and relationship to discharge density limit in Alcator C-Mod

Invited Talk

Paper - Physics of Plasmas 8 (2001) 2107

Press Release

PSI 2000, Rosenhiem, Germany - Cross-Field Plasma Transport and Main Chamber Recycling in Diverted Plasmas on Alcator C-Mod

Invited Talk

Paper - Nuclear Fusion 40 (2000)

APS 1999, Seattle, WA - Cross-Field Particle Transport through the Separatrix and Scrape-off Layer in Alcator C-Mod

Contributed Oral

Initial Results of the Alcator C-Mod Quasi-Coherent Mode Antenna

T. Golfinopolous, APS2012 Poster.

A 'Shoelace' Antenna System for Direct Excitation of C-Mod's Quasi-Coherent Mode (QCM) and Boundary Layer Turbulence

B. LaBombard, APS2011 Poster.

T. Golfinopolous, APS2011 Poster.

*Mirror Langmuir Probe Development*

A "Mirror Langmuir Probe" is Being Developed -- A Powerful New Technique to Measure Boundary n, Te, Phi Profiles and Turbulence

APS2012 Contributed Oral.

Mirror Langmuir probe: A technique for real-time measurement of magnetized plasma conditions using a single Langmuir electrode

Rev. Sci. Instrum. 78 (2007) 073501.

Construction and operation of a Mirror Langmuir Probe Diagnostic for the Alcator C-Mod Tokamak

L. Lyons Master's Thesis, 2007.

*Edge Plasma Flow Diagnostic Development*

Plasma Flows in the Alcator C-Mod Scrape-off Layer.

N. Smick Doctoral Thesis, 2009.

(WASP) Wall scanning probe for high-field side plasma measurements on Alcator C-Mod.

Rev. Sci. Instrum. 80, 023502 (2009).

Space charge limits of ion sensitive probes.

D Brunner et al Plasma Phys. Control. Fusion 55 125004 (2013)

Scanning retarding field analyzer for plasma profile measurements in the boundary of the Alcator C-Mod tokamak

D. Brunner, et al., Rev. Sci. Instrum. 84 , 033502 (2013).

Scanning ion sensitive probe for plasma profile measurements in the boundary of the Alcator C-Mod tokamak

D. Brunner, et al., Rev. Sci. Instrum. 84 , 053507 (2013).

Development of Probes for Assessment of Ion Heat Transport and Sheath Heat Flux in the Boundary of the Alcator C-Mod Tokamak.

D. Brunner, Doctoral Thesis, 2013.

*Verification of Plasma-Sheath Heat Transfer Physics using Surface Thermocouple Diagnostic*

Surface thermocouples for measurement of pulsed heat flux in the divertor of the Alcator C-Mod tokamak

D. Brunner and B. LaBombard, Rev. Sci. Instrum. 83 (2012) 033501

*Edge Plasma Ion Mass Spectroscopy*

Omegatron Ion Mass Spectrometer - Review of Scientific Instruments 71 (2000) 4107:

Omegatron Ion Mass Spectrometer for the Alcator C-Mod Tokamak

Helium-3 Transport Experiments with Omegatron - Physics of Plasmas 7 (2000) 4573:

*Impurity Dispersal 'Plume' Experiments*

Impurity Plume Experiments: physics and detailed modeling - Plasma Phys. Control. Fusion 46 (2004) 1617.

Impurity plume experiments in the edge plasma of the Alcator C-Mod Tokamak

Impurity Dispersal 'Plumes' - Journal of Nuclear Materials 290-2939 (2001) 598

Impurity Transport Experiments in the Edge Plasmaof Alcator C-Mod using Gas Injection Plumes

Novel Tracer Gas Injecting Probe System - Journal of Nuclear Materials 266-269 (1999) 571

*Alcator C-Mod Cryopump Development*

Design, installation and commissioning of the upper divertor cryopump system in Alcator C-Mod

PSFC/RR-08-06-

APS 2007, Orlando, FL - Design and operation of a novel cryopumping system in Alcator C-Mod

Contributed Poster

*1-D Space,2-D Velocity Kinetic Neutral Transport Code written in IDL**

PSFC Research Report: PSFC/RR-01-9 (KN1D.pro)

KN1D source code can be found here

PSFC Research Report: PSFC/RR-00-9 (Kinetic_Neutrals.pro)

A 1-D Space, 2-D Velocity, Kinetic Neutral Transport Algorithm

* IDL is a trademark of Research Systems, Inc., Boulder, CO

Last Revised: 11/7/2013