Welcome!

Profile Image I'm a research scientist at the Space Science Institute (and visiting researcher at UCLA) working with plasma, the fourth state of matter. To find out more about why plasma matters, see the video of me on the "Outreach" tab. Click any of the other tabs to learn more about my work.
Click here for my contact information.

RESEARCH

I look at key processes both in basic laboratory experiments and in satellite data to see how plasma behaves. Click the circles below for more!
  • I’m currently working to put together the hardware necessary to deploy a relativistic electron beam on the Large Plasma Device (LAPD) to study the waves generated and how the beam propagates through the plasma. The physics we learn will aid future missions to put electron beams on spacecraft where they can trace magnetic field lines, allowing us to see how space weather disturbs the field. Results will also improve our understanding of radio bursts thought to be generated by energetic electron beams on the sun. Preliminary experiments with a lower energy (20keV) beam show robust wave generation via a Landau resonance process. Supported by NSF (PHY-1707275) and NASA (80NSSC18K1232).
  • My work with Dr. Troy Carter focuses on non-linear interactions between Alfvén waves, the fundamental magnetic mode of plasmas. Alfvén waves are thought to play a key role in the heating of the solar corona, the nature of the turbulent solar wind, and energetic particle loss in tokamaks. In all three contexts, the decay of a large amplitude Alfvén wave may be an important mechanism. Recent experiments we conducted on the Large Plasma Device (LAPD) represent the first fundamental laboratory study of the non-linear interactions responsible for Alfvén wave decay instabilities, including:
    --- Laboratory observation of the Alfvén-acoustic mode coupling at the heart of the Parametric Decay Instability. (Read our PRL paper)
    --- The first observation of a sheer Alfvén wave parametric instability in the laboratory.  (Read our PRL paper)
  • The ion foreshock region upstream of the Earth's bow shock is a prime natural laboratory for the study of non-linear Alfvén wave interactions. An ion beam accelerated from the shock front back into the solar wind may interact with the solar wind core to generate large-amplitude, Ultra Low Frequency (ULF) waves at a small fraction of the ion cyclotron frequency. In this GRL paper, we show the first satellite measurement of the ULF wave growth rate. The measured growth rate is consistent with dispersion solver results for observed ion distributions, validating resonant beam instability theory. Results will inform future missions near shocks and future non-linear studies related to turbulence and dissipation in the heliosphere.
  • I completed my PhD work with Drs. Hantao Ji and Masaaki Yamada on the Magnetic Reconnection Experiment (MRX) at Princeton. We studied impulsive reconnection events observed in the experiment in which a build-up of magnetic energy is followed by a quick release and concluded that 3-D physics is necessary to explain the observations. This has implications for similar events that occur in space and laboratory plasmas, including the Earth's magnetotail. Read our GRL paper here.

    Earlier in my PhD work, I modified and ran 2.5-D, fully kinetic PIC simulations with MRX geometry and boundary conditions under the guidance of Drs. Bill Daughton and Vadim Roytershteyn. We found a that the ion-scale features of these simulations well match MRX data, but discrepancies persist in the electron-scale physics. Read our PoP paper here.

PUBLICATIONS

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S. Dorfman and T. A. Carter, "Observation of an Alfvén Wave Parametric Instability in a Laboratory Plasma," Phys. Rev. Lett. 116, 195002 (2016).

S. Dorfman, H. Hietala, P. Astfalk, and V. Angelopoulos, "Growth Rate Measurement of ULF Waves in the Ion Foreshock," Geophys. Res. Let. 44 (2017).

S. Dorfman and T. A. Carter, "Nonlinear Excitation of Acoustic Modes by Large-Amplitude Alfvén Waves in a Laboratory Plasma," Phys. Rev. Lett. 110, 195001 (2013).

S. Dorfman and T. A. Carter, "Non-linear Alfvén wave interaction leading to resonant excitation of an acoustic mode in the laboratory," Phys. Plasmas 22, 055706 (2015).

S. Dorfman, H. Ji, M. Yamada, J. Yoo, T. Tharp, E. Lawrence, C. Myers., "Three-dimensional, Impulsive Magnetic Reconnection in a Laboratory Plasma," Geophys. Res. Let. 40, 233-238 (2013).

S. Dorfman, W. Daughton, V. Roytershteyn, H. Ji, Y. Ren, and M. Yamada, "Two-dimensional fully kinetic simulations of driven magnetic reconnection with boundary conditions relevant to the Magnetic Reconnection Experiment," Phys. Plasmas 15, 102107 (2008).

S. Dorfman, H. Ji, M. Yamada, J. Yoo, T. Tharp, E. Lawrence, C. Myers., "Experimental Observation of 3-D, Impulsive Reconnection Events in a Laboratory Plasma," Phys. Plasmas 21, 012109 (2014).

S. Dorfman, Experimental study of 3-D, impulsive reconnection events in a laboratory plasma, Ph.D. thesis, Princeton University (2012).

S. Dorfman, et al, "Electromagnetic Perturbations in the Reconnecting Current Sheet in MRX." AIP Conf. Proc. 871, 306 (2006).

V. Roytershteyn, S. Dorfman, W. Daughton, H. Ji, M. Yamada, and H. Karimabadi, "Electromagnetic instability of thin reconnection layers: Comparison of three-dimensional simulations with MRX observations." Phys. Plasmas 20, 061212 (2013).

V. Roytershteyn, W. Daughton, S. Dorfman, Y. Ren, H. Ji, M. Yamada, H. Karimabadi, L. Yin, B.J. Albright, and K.J. Bowers, "Driven magnetic reconnection near the Dreicer limit", Phys. Plasmas 17, 055706 (2010).

N. Jain, J. B�chner, S. Dorfman, H. Ji, and A. S. Sharma, "Current disruption and its spreading in collisionless magnetic reconnection." Phys. Plasmas 20(11), 112101 (2013).

H. Ji, Y. Ren, M. Yamada, S. Dorfman, W. Daughton, and S. P. Gerhardt , "New insights into dissipation in the electron layer during magnetic reconnection," Geophys. Res. Let. 35 L13106 (2008).

Y. Ren, M. Yamada, H. Ji, S. Dorfman, S. P. Gerhardt, and R. Kulsrud, "Experimental study of the Hall effect and electron diffusion region during magnetic reconnection in a laboratory plasma," Phys. Plasmas 15, 082113 (2008).

T. D. Tharp, M. Yamada, H. Ji, E. Lawrence, S. Dorfman, C. E. Myers, and J. Yoo, "Quantitative Study of Guide-Field Effects on Hall Reconnection in a Laboratory Plasma." Phys. Rev. Lett. 109, 165002 (2012).

T. D. Tharp, M. Yamada, H. Ji, E. Lawrence, S. Dorfman, C. Myers, J. Yoo, Y M. Huang, and A. Bhattacharjee, "Study of the effects of guide field on Hall reconnection." Phys. Plasmas 20 , 055705 (2013).

AWARDS

NASA Early Career Investigators Program Award (2019)
UCLA Chancellor's Award for Postdoctoral Research, Honorable Mention (2015)
NASA Jack Eddy Postdoctoral Fellowship (2014)
AGU Basu United States Early Career Award (2013)
AGU Scarf Award for Outstanding PhD Thesis (2013)
DOE Fusion Energy Sciences Postdoctoral Fellowship (2011)
National Defense Science and Engineering Graduate Fellowship (2007)
DOE Fusion Energy Sciences Fellowship (2006)
Thomas H. Stix Prize in Plasma Physics (2006)
Joel Matthew Orloff Award for Highest Scholarship in Physics at MIT (2005)
Carl Oberman Fellowship in Plasma Physics (2005)
Princeton First Year Science and Engineering Fellowship (2005)
Inducted into Phi Beta Kappa and Sigma Pi Sigma (2005)
National Merit $2500 Scholarship (2001)
Derivation of Shot Noise theory added to Junior Lab Course Reader (2004)

OUTREACH

In today's environment of flat-line budgets for research and increased public skepticism, it's important to get the word out on why science matters. I love giving talks to general audiences, so don't hesitate to email me with speaking invitations.
Play video --> Play the video on the left to watch me explain plasma in three minutes.
Click here to listen to a podcast about my work on the Large Plasma Device. I've previously spoken at the Santa Monica Public Library, Nerd Nite, Pint of Science, Mindshare, and UCLA's Falling Walls Lab. My initiatives include Global Plasma Month (2015) and the Los Angeles High Table living room speaker series (2014-present).