Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Generation of laboratory nanoflares from multiple braided plasma loops

Nature Astronomy volume 7, pages 655–661 (2023)Cite this article

Subjects

Abstract

Solar flares are intense bursts of electromagnetic radiation accompanied by energetic particles and hard X-rays. They occur when magnetic flux loops erupt in the solar atmosphere. Solar observations detect energetic particles and hard X-rays but cannot reveal the generating mechanism because the particle acceleration happens at a scale smaller than the observation resolution. Thus, details of the cross-scale physics that explain the generation of energetic particles and hard X-rays remain a mystery. Here, we present observations from a laboratory experiment that simulates solar coronal loop physics. Transient, localized 7.6-keV X-ray bursts and a several-kilovolt voltage spike are observed in braided magnetic flux ropes of a 2-eV plasma when the braid strand radius is choked down to be at the kinetic scale by either magnetohydrodynamic (MHD) kink or magnetic Rayleigh–Taylor instabilities. This sequence of observations reveals a cross-scale coupling from MHD to non-MHD physics that is likely responsible for generating solar energetic particles and X-ray bursts. All the essential components of this mechanism have been separately observed in the solar corona.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on SpringerLink
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Experimental setup.
Fig. 2: Time series images of experimental plasma loop evolution and X-ray and voltage measurements.
Fig. 3: X-ray energy measurements.
Fig. 4: Two experimental nanoflare events.
Fig. 5: Comparison between solar observation and experimental observation.

Similar content being viewed by others

Data availability

The experimental data reported here were generated by the Caltech Solar Loop Experiment and have been uploaded to https://data.caltech.edu/records/rcrh7-7ps89.

Code availability

Information about LTspice circuit simulation software is available at https://www.analogue.com/en/design-centre/design-tools-and-calculators/ltspice-simulator.html.

References

  1. Cirtain, J. W. et al. Energy release in the solar corona from spatially resolved magnetic braids. Nature 493, 501–503 (2013).

    Article  ADS  Google Scholar 

  2. Testa, P. et al. Evidence of nonthermal particles in coronal loops heated impulsively by nanoflares. Science 346, 1255724 (2014).

    Article  Google Scholar 

  3. Fleishman, G. D. et al. Decay of the coronal magnetic field can release sufficient energy to power a solar flare. Science 367, 278–280 (2020).

    Article  MathSciNet  MATH  ADS  Google Scholar 

  4. Bahauddin, S. M., Bradshaw, S. J. & Winebarger, A. R. The origin of reconnection-mediated transient brightenings in the solar transition region. Nat. Astron. 5, 237–245 (2021).

    Article  ADS  Google Scholar 

  5. Fleishman, G. D., Nita, G. M., Chen, B., Yu, S. & Gary, D. E. Solar flare accelerates nearly all electrons in a large coronal volume. Nature 6, 674–677 (2022).

    Article  ADS  Google Scholar 

  6. Lemen, J. R. et al. in The Solar Dynamics Observatory (Eds Pesnell, W. D. et al.) 17–40 (Springer, 2011).

  7. Kobayashi, K. et al. The high-resolution coronal imager (Hi-C). Solar Phys. 289, 4393–4412 (2014).

    Article  ADS  Google Scholar 

  8. Parker, E. Magnetic neutral sheets in evolving fields. I. General theory. Astrophys. J. 264, 635–647 (1983).

    Article  ADS  Google Scholar 

  9. Parker, E. Nanoflares and the solar X-ray corona. Astrophys. J. 330, 474–479 (1988).

    Article  ADS  Google Scholar 

  10. Alfvén, H. & Carlqvist, P. Currents in the solar atmosphere and a theory of solar flares. Solar Phys. 1, 220–228 (1967).

    Article  ADS  Google Scholar 

  11. Carlqvist, P. Current limitation and solar flares. Solar Phys. 7, 377–392 (1969).

    Article  ADS  Google Scholar 

  12. Stenson, E. V. & Bellan, P. Magnetically driven flows in arched plasma structures. Phys. Rev. Lett. 109, 075001 (2012).

    Article  ADS  Google Scholar 

  13. Ha, B. N. & Bellan, P. M. Laboratory demonstration of slow rise to fast acceleration of arched magnetic flux ropes. Geophys. Res. Lett. 43, 9390–9396 (2016).

    Article  ADS  Google Scholar 

  14. Wongwaitayakornkul, P., Haw, M. A., Li, H., Li, S. & Bellan, P. M. Apex dips of experimental flux ropes: helix or cusp? Astrophys. J. 848, 89 (2017).

    Article  ADS  Google Scholar 

  15. Haw, M. A., Wongwaitayakornkul, P., Li, H. & Bellan, P. M. Reverse current model for coronal mass ejection cavity formation. Astrophys. J. Lett. 862, L15 (2018).

    Article  ADS  Google Scholar 

  16. Wongwaitayakornkul, P., Haw, M. A., Li, H. & Bellan, P. M. Magnetically induced current piston for generating extreme-ultraviolet fronts in the solar corona. Astrophys. J. 874, 137 (2019).

    Article  ADS  Google Scholar 

  17. Zhang, Y., Wongwaitayakornkul, P. & Bellan, P. M. Magnetic Rayleigh–Taylor instability in an experiment simulating a solar loop. Astrophys. J. Lett. 889, L32 (2020).

    Article  ADS  Google Scholar 

  18. Newcomb, W. A. Hydromagnetic stability of a diffuse linear pinch. Ann. Phys. 10, 232–267 (1960).

    Article  MATH  ADS  Google Scholar 

  19. Zhou, Y., Pree, S. & Bellan, P. M. Imaging suprathermal X-rays from a laboratory plasma jet using PIN-diode-based and scintillator-based 1D pinhole/coded aperture cameras. Rev. Sci. Instruments 94, 013504 (2023).

    Article  ADS  Google Scholar 

  20. Henke, B. L., Gullikson, E. M. & Davis, J. C. X-ray interactions: photoabsorption, scattering, transmission, and reflection at E = 50–30,000 eV, Z = 1–92. Atomic Data Nuclear Data Tables 54, 181–342 (1993).

    Article  ADS  Google Scholar 

  21. Buneman, O. Dissipation of currents in ionized media. Phys. Rev. 115, 503–517 (1959).

    Article  MathSciNet  MATH  ADS  Google Scholar 

  22. Engelhardt, M. LTspice owned by Analog Devices Inc. Version 17.1.8 https://www.analog.com/en/design-center/design-tools-and-calculators/ltspice-simulator.html (2023).

  23. Moser, A. L. & Bellan, P. M. Magnetic reconnection from a multiscale instability cascade. Nature 482, 379–381 (2012).

    Article  ADS  Google Scholar 

  24. Kruskal, M. D. & Schwarzschild, M. Some instabilities of a completely ionized plasma. Proc. Royal Soc. Lond. Ser. A Math. Phys. Sci. 223, 348–360 (1954).

    MathSciNet  MATH  ADS  Google Scholar 

  25. Ryutov, D., Drake, R. & Remington, B. Criteria for scaled laboratory simulations of astrophysical MHD phenomena. Astrophys. J. Suppl. Ser. 127, 465 (2000).

    Article  ADS  Google Scholar 

  26. Sullivan, C. R. & Zhang, R. Y. Simplified design method for litz wire. In 2014 IEEE Applied Power Electronics Conference and Exposition-APEC 2014 2667–2674 (IEEE, 2014).

  27. Stix, T. H. Magnetic braiding in a toroidal plasma. Phys. Rev. Lett. 30, 833 (1973).

    Article  ADS  Google Scholar 

  28. Aschwanden, M. Physics of the Solar Corona: An Introduction with Problems and Solutions (Springer Science & Business Media, 2006).

    Google Scholar 

  29. Srivastava, A., Zaqarashvili, T., Kumar, P. & Khodachenko, M. Observation of kink instability during small B5.0 solar flare on 2007 June 4. Astrophys. J. 715, 292 (2010).

    Article  ADS  Google Scholar 

  30. Hillier, A. The magnetic Rayleigh–Taylor instability in solar prominences. Rev. Modern Plasma Phys. 2, 1 (2018).

    Article  ADS  Google Scholar 

  31. Kumar, P., Cho, K.-S., Bong, S.-C., Park, S.-H. & Kim, Y. Initiation of coronal mass ejection and associated flare caused by helical kink instability observed by SDO/AIA. Astrophys. J. 746, 67 (2012).

    Article  ADS  Google Scholar 

  32. Lin, R. P. et al. in The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) (Eds Lin, R. P. et al.) 3–32 (Springer, 2003).

  33. Ergun, R. et al. Observations of double layers in Earth’s plasma sheet. Phys. Rev. Lett. 102, 155002 (2009).

    Article  ADS  Google Scholar 

Download references

Acknowledgements

This material is based upon work supported by the NSF (Awards 1914599 and 2105492 to P.M.B.). The X-ray detector used in this work was developed with support from the USDOE ARPA-E (Grant DE-AR0001159 to P.M.B.).

Author information

Authors and Affiliations

  1. Applied Physics and Materials Science, California Institute of Technology, Pasadena, CA, USA

    Yang Zhang, Seth Pree & Paul M. Bellan

Authors
  1. Yang Zhang
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Seth Pree
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Paul M. Bellan
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

Y.Z. designed the braided loop experiment from the suggestions and guidance of P.M.B. S.P. built the X-ray camera from the suggestions and guidance of P.M.B. Y.Z. and S.P. performed the experiment. The interpretation of the results was done jointly by all authors. Y.Z. drafted the manuscript. All authors revised the manuscript together.

Corresponding author

Correspondence to Yang Zhang.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Astronomy thanks Markus Aschwanden and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Solar loop experiment circuit simulation.

(a) Experiment circuit diagram. The plasma part of the circuit is represented as an inductor and a time-dependent resistor. The plasma inductance is assumed to be 50 nH, which is obtained by simplifying the plasma loop as a half circle loop of wire with 5 cm loop major radius and 1 cm minor (wire) radius. The voltage and current spikes are both peak functions, so the corresponding resistance change is presumed to be also a peak function. We use Gaussian function \({R}_{plasma}={R}_{0}\exp (-a{(t-{t}_{0})}^{2})\) to represent the transient change of the plasma resistance where R0 is the peak resistance value, and t0 is the resistance peak time, and a is related to the full width at half maximum (FWHM). They are chosen according to the relative voltage spike amplitude, voltage peak time and the voltage spike FWHM. In the simulation, R0 = 0.4Ω, t0 = 3.65 μs and a = 5 μs −2 are used. The corresponding plasma resistance is plotted in (b). (c, d) Voltage and current measurement from experiment Shot # 9258. As shown in (a), the voltage measured in (c) is the voltage across the plasma part and an extra inductor. We also measured the voltage across the plasma part by connecting two voltage probes directly to the top electrode and bottom electrode and then subtracting the two voltages. The voltage trace across the plasma is similar but has a several kV larger voltage spike compared with (c). (e, f) Voltage and current curves from the simulation. Voltage and current spikes similar to the experimentally observed spikes are reproduced by the transient resistance increase.

Extended Data Fig. 2 Magnetic Rayleigh Taylor instability observation.

A four-strand braided structure is shown in time series images of hydrogen plasma loop evolution. With the expansion of the plasma loop, a magnetic Rayleigh Taylor instability occurs on the loop and plays the same role as a kink instability to choke the strand radius down and break the strand at later time. The full evolution video can be found in Supplementary Movie 2.

Supplementary information

Supplementary Video 1

This video shows an example of braided plasma loop evolution where a kink instability develops on the top of the loop starting at around 2.68 μs.

Supplementary Video 2

This video shows an example of braided plasma loop evolution where a magnetic Rayleigh–Taylor instability develops on the loop starting at around 2.54 μs.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Zhang, Y., Pree, S. & Bellan, P.M. Generation of laboratory nanoflares from multiple braided plasma loops. Nat Astron 7, 655–661 (2023). https://doi.org/10.1038/s41550-023-01941-x

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41550-023-01941-x

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing