2.1 Leadership structure

In 2022, the MagNetUS community established that the organization would be led by three elected officers, along with elected leaders of several working groups geared toward specific tasks. At present, the working groups and descriptions of their responsibilities are as follows:

• • Annual meeting working group: organizes the annual MagNetUS meeting, including preparation of the scientific agenda.

• • Facilities working group: coordinates communications and activities among collaborative experimental facilities. Works with funding agencies as appropriate to coordinate joint calls for facility run time.

• • User base working group: advocates for facility users and addresses their needs and concerns. Develops publicity and on-boarding strategies to cultivate, welcome and assist new users.

• • Outreach, education and workforce development working group: coordinates outreach and educational programs, such as workshops, internships and science communication events.

• • Software and data management working group: advocates for sustainable and open software development, works toward implementing metadata standards and coordinates joint numerical projects and data-mining efforts.

Additionally, ad hoc working groups can be formed as needed to address specific issues that arise. For example, an ad hoc working group has been formed within the MagNetUS community to plan for a next-generation experimental facility to study the physics of collisionless, magnetized, high beta plasmas, such as the plasma in the solar wind and other astrophysical environments, where beta is the ratio of plasma pressure to magnetic pressure.

2.2 Scientific scope

Within the scope of DPS relevant to magnetized plasmas, the MagNetUS community has chosen not to limit participation to any particular research thrusts or priorities, so as to be inclusive to a wide range of plasma researchers. This encourages a wider variety of topics to be shared and promotes intellectual diversity in the network. However, several topics have been identified as important to the community based on presentations at the annual meeting, ongoing discussions and usage of the associated facilities. These include turbulence; collisionless dissipation and other kinetic-scale phenomena; dust dynamics; magnetic reconnection; non-thermal particle acceleration; plasma–material interactions; shocks and compressibility; non-neutral plasmas; waves and instabilities; self-organization and pattern formation; vortices and coherent structures; transport phenomena; and high-beta, flow-dominated plasma behaviour. Hardware and software techniques, such as diagnostic development, data analysis and numerical simulation methods, are also a priority. These subjects are of broad interest due to their importance in fusion science and technology, space and astrophysics, and low-temperature plasma science. Although emphasis within MagNetUS is placed on magnetized plasma research in the laboratory, naturally occurring (e.g. astrophysical) plasmas are important to the community, as are plasmas with varying degrees of magnetization.

Priorities for DPS research in the USA are guided in part by several recent national reports: ‘Plasma: at the frontier of scientific discovery’ (Adamovich et al. Reference Adamovich, Anders, Baalrud, Bale, Bonitz, Brizard, Carter, Cary, Daligault and Danielson2017), ‘A Community Plan for Fusion Energy and Discovery Plasma Sciences’ (Baalrud et al. Reference Baalrud, Ferraro, Garrison, Howard, Kuranz, Sarff and Solomon2020) and ‘Powering the Future: Fusion and Plasmas’ (Fusion Energy Sciences Advisory Committee - FESAC 2021). The first report is dedicated entirely to DPS, whereas the latter two reports contain separate sections regarding fusion science and DPS research. Taken together, these reports offer a comprehensive overview of the state of DPS research and important future directions. Many topics emphasized in these reports are relevant to research represented in MagNetUS, including self-organization; conversion between magnetic and kinetic energy in plasmas; low-temperature plasma chemistry; non-equilibrium and interfacial plasmas; strongly coupled, quantum-mechanical and antimatter plasmas; the origin of magnetic fields in astrophysical systems; and extreme or explosive events in astrophysical plasmas.

2.3 Participation and funding

Participation in MagNetUS activities is open, and presently free of charge, to any researcher or worker of any background or career stage involved in plasma science. It may include attending and presenting at annual meetings, involvement in the Joint Call for facility run time described in § 3 or involvement in working group projects. At present, the MagNetUS organization is not directly funded in a centralized way. Instead, progress has been supported through the participating facilities and research groups. In some cases, dedicated funding has been pursued by individuals through their home institutions on behalf of the organization (e.g. for supporting annual meetings).

2.4 Workforce development

Importantly, the MagNetUS and DPS communities play an integral role in building a skilled and diverse workforce capable of meeting the demands of the growing plasma-relevant industries, including the semiconductor, nanotechnology, fusion, space and defence industries, to name a few. Dedicated effort is needed to introduce plasma Science, Technology, Engineering and Mathematics (STEM) courses, provide technical training and offer networking opportunities to facilitate successful transitions in plasma-relevant careers. University-based DPS research, in conjunction with MagNetUS, can introduce science-inclined individuals to plasma STEM by tapping into a pool of motivated students. University experiments are often relatively small and flexible, thus, providing excellent hands-on training and experience that may not be feasible at larger public or private facilities. Engagement and education efforts organized by MagNetUS will provide an avenue to introduce young minds to plasma STEM, including those at Primarily Undergraduate Institutions (PUIs), Community Colleges, Minority Serving Institutions (MSIs) and high schools. Networking opportunities facilitated by MagNetUS (e.g. meetings and joint projects) connect students to other research groups and potential career paths. Training opportunities are planned through MagNetUS to help students and early-career scientists build marketable skill sets attractive to employers in plasma-relevant industries and beyond. Finally, the Joint Call framework broadens participation in plasma physics by making experimental resources available to students, early career faculty and scientists and other colleagues who may not have these capabilities at their home institution. MagNetUS activities help spread awareness of these opportunities and bring new and diverse personnel into the field. In the near term, our goal is to train scientists to fulfil the increasing demand for plasma-relevant skills in industry. In the long term, we aim to build an ecosystem where the next generation of plasma scientists can be nurtured and supported.

The MagNetUS community has also been highly supportive of the recently founded Plasma Network for Education and Training (PlasmaNET). The main goal of PlasmaNET is to build a community-based network of people interested in public engagement, education, broadening participation and workforce development for plasma science. Specific goals include supporting newly hired plasma outreach coordinators through resources, workshops and shared data, helping plasma professionals formalize their broader impact work so that they gain recognition for such work from their departments/institutions, and developing effective assessment tools. MagNetUS members have supported PlasmaNET through member participation, contribution of resources and coordination of PlasmaNET events, including the 2022 APS-DPP mini-conference titled ‘Workforce Development Through Research-Based, Plasma-Focused Science Education and Public Engagement’ and the 2024 PlasmaNET Workshop on ‘Plasma Communication and Engagement’. Members of the MagNetUS community co-authored a summary report (Kostadinova et al. Reference Kostadinova, Greco, Murdock, Barraza-Valdez, Hasson, Harper, West-Abdallah, Harper, Brown and Scime2023) after the mini-conference and coordinated the timing and co-location of the PlasmaNET workshop and the 2024 MagNetUS meeting.

3.1 Basic Plasma Science Facility

The Basic Plasma Science Facility (BaPSF) is a collaborative research facility located at the University of California Los Angeles in Los Angeles, CA.Footnote ³ It participates regularly in the Joint Call. It features the cylindrical Large Plasma Device (LAPD) (Gekelman et al. Reference Gekelman, Pfister, Lucky, Bamber, Leneman and Maggs1991, Reference Gekelman, Pribyl, Lucky, Drandell, Leneman, Maggs, Vincena, Van Compernolle, Tripathi and Morales2016) and several smaller experiments. The LAPD is a 20 m long, 1 m diameter cylindrical vacuum vessel with an axially oriented magnetic field that can generate a steady-state, large volume, magnetized ambient plasma with excellent shot-to-shot reproducibility at high repetition rates (up to 1 Hz). The machine can produce variable background magnetic field profiles along its length, variable ambient gas fills (e.g. H, He, Ne, Ar and mixtures) and variable ambient densities. The plasma is generated using up to two LaB$_{6}$ (lanthanum hexaboride) cathodes on either end of the machine. The device has a large number of diagnostic ports distributed axially and azimuthally throughout the machine and is highly configurable. It also features automatic probe steppers that can gather volumetric plasma data across many consecutive shots using a wide range of physical probes.

The LAPD at BaPSF is highly configurable, which results in a wide variety of plasma phenomena that can be studied, including turbulent transport, the nonlinear behaviour of Alfvén waves, magnetized collisionless shocks, wave/particle interactions, helicon wave propagation and coupling and magnetic reconnection. Just a few recent experiments since the inception of MagNetUS are described here. Shear Alfvén wave reflection has been observed for the first time from a gradient in the Alfvén speed where the ratio of the gradient scale length to the Alfvén wavelength was matched to conditions relevant to those of solar coronal holes (Bose et al. Reference Bose, TenBarge, Carter, Hahn, Ji, Juno, Savin, Tripathi and Vincena2024). In another experiment, shear Alfvén waves were launched within a kink-unstable magnetic flux rope; a three-wave interaction between the launched wave and the kink oscillation generated Alfvén wave sidebands with smaller perpendicular structures that approached dissipation scales (Vincena et al. Reference Vincena, Tripathi, Gekelman and Pribyl2024). A high repetition rate laser (1 Hz, 12 J over 20 ns) was used to create a laser blow-off plasma that produced magnetic reconnection when fired into a dipole magnetic field embedded within the background LAPD plasma (Rovige et al. Reference Rovige, Cruz, Dorst, Pilgram, Constantin, Vincena, Cruz, Silva, Niemann and Schaeffer2024); this allowed the study of Hall fields associated with the reconnection in an experiment relevant to ion-scale magnetospheres as can be found on local regions of the Moon. In a completely different reconnection experiment, field-aligned ion beams were observed when two kink-unstable flux ropes collided to drive the reconnection (Tang, Gekelman & Sydora Reference Tang, Gekelman and Sydora2023). Finally, multiple plasma pressure filaments were arranged to generate unstable perturbations that drove convective mixing of the filaments; nonlinear gyro-kinetic simulations confirmed the perturbations were drift-Alfvén waves (Sydora et al. Reference Sydora, Simala-Grant, Karbashewski, Jimenez, Van Compernolle and Poulos2024).

3.2 The DIII-D National Fusion Facility

The DIII-D National Fusion Facility (Luxon Reference Luxon2002) is a DOE user facility, operated by General Atomics in San Diego, California.Footnote ⁴ It is one of the premier experimental platforms for advanced tokamak research. While its primary research is in fusion, a portion of run time is dedicated to DPS, which is regularly awarded through the Joint Call. The DIII-D is a large magnetic confinement device designed to study the conditions necessary for sustained nuclear fusion, with the ultimate goal of generating electricity through fusion power. The facility's versatile configuration allows for a wide range of experiments aimed at understanding plasma behaviour, improving confinement and developing advanced control techniques. The DIII-D has made significant contributions to the development of the H-mode, a high-confinement regime critical for future fusion reactors. Equipped with an array of diagnostics including magnetic probes, Thomson scattering and charge-exchange recombination spectroscopy, DIII-D provides detailed measurements of plasma parameters such as temperature, density and current profiles. The facility's flexible design supports various plasma shapes and configurations, including elongated, shaped plasmas that are more relevant to reactor design. Additionally, the DIII-D's advanced heating systems, including neutral beam injection and electron cyclotron heating, enable precise control over plasma conditions. Research at DIII-D spans key areas such as transport and turbulence, edge localized modes, disruption mitigation and the development of innovative plasma-facing materials. As a user facility, DIII-D fosters extensive collaboration with researchers from around the world, driving progress toward the realization of practical fusion energy. The insights gained from DIII-D experiments directly inform the design and operation of next-generation fusion devices, such as ITER and future fusion power plants, making it a cornerstone of international fusion research efforts.

The DIII-D tokamak plays a crucial role in advancing plasma physics, particularly within the Frontier Science program. One of the key areas of research involves wave–particle interactions, where non-Maxwellian gradients drive instabilities that lead to redistribution of energetic particles such as runaway electrons. This can impact energy transport and influence turbulence and magnetohydrodynamic (MHD) modes, including Alfvén eigenmodes (Spong et al. Reference Spong, Heidbrink, Paz-Soldan, Du, Thome, Van Zeeland, Collins, Lvovskiy, Moyer and Austin2018). The facility's ability to study high-$\beta$ plasmas makes it an ideal platform for understanding electromagnetic effects on turbulence, which has parallels in astrophysical systems. Magnetic islands, which can increase transport and disrupt confinement, are systematically controlled in DIII-D to study their effects on plasma stability and turbulence (Williams et al. Reference Williams, Pueschel, Terry, Nishizawa, Kriete, Nornberg, Sarff, McKee, Orlov and Nogami2020). Magnetic reconnection is another major research focus at DIII-D, including investigations of fast reconnection processes, heat transport and the role of plasmoid instabilities in these events. Material science experiments have been conducted as well, particularly in the development of heat-resistant materials for aerospace applications. For example, carbon ablation experiments at DIII-D replicated conditions experienced by the Galileo probe during its entry into Jupiter's atmosphere, providing valuable data for spacecraft design and fusion research (Orlov et al. Reference Orlov, Hanson, Escalera, Taheri, Villareal, Zubovic, Bykov, Kostadinova, Rudakov and Ghazinejad2021). Recent studies on the edge of L-mode plasmas have explored the role of density fluctuation statistics and turbulence spreading, particularly using beam emission spectroscopy. These experiments have revealed significant insights into how density blobs and voids propagate at the plasma edge, affecting turbulence spreading and contributing to the broader understanding of heat flux width in the scrape-off layer (Khabanov et al. Reference Khabanov, Hong, Diamond, Tynan, Yan, McKee, Chrystal, Scotti, Yu and Zamperini2024).

3.3 Magnetized Plasma Research Laboratory

The Magnetized Plasma Research Laboratory (MPRL) is a collaborative research facility located at Auburn University in Auburn, AL, and regularly participates in the Joint Call.Footnote ⁵ It largely focuses on low-temperature magnetized plasmas, including dusty plasmas, using its flagship device, the Magnetized Dusty Plasma Experiment (MDPX) (Thomas, Merlino & Rosenberg Reference Thomas, Merlino and Rosenberg2012). The MDPX features a 4 T superconducting split-bore magnet system with excellent axial and radial diagnostic access. The original MDPX plasma device had a capacitively coupled radio-frequency plasma source to produce space plasma relevant conditions and plasmas similar to those used in the semiconductor processing industry. An interesting feature of MDPX is that the whole plasma chamber, including the plasma source (capacitively coupled, inductively coupled, laser ablation, DC sources, etc.) can be swapped between different experiments, thus allowing different types of experiments led by the larger low-temperature and dusty plasma community. The MPRL also includes the ALEXIS (Auburn Linear EXperiment for Instability Studies) mid-scale linear plasma device to investigate plasma instabilities and transport relevant to the ionosphere and the magnetosphere. In addition, there are several smaller table-top unmagnetized plasma devices that are specifically designed to be compatible with MDPX for future magnetized plasma studies. Some of the current student-driven research being pursued at MPRL encompass a large range of topics such as pattern formation of filamentary structures in magnetized plasmas, nanoparticle growth in plasmas, laser trapping of dust particles, studies of dust clusters and dust thermodynamics, laser blow off at high magnetic fields, dust acoustic waves in magnetized plasmas, controlling dust charging and dynamics by externally applied UV light, investigating externally imposed ordered structures, using dust as a diagnostic and development of new laser-based non-perturbative plasma diagnostics. The MPRL laboratory also actively tries to involve researchers and professors from PUI(s) and MSI(s) to encourage undergraduate research and routinely hosts research experience for undergraduate students.

Examples of recent collaborative research projects conducted at MPRL include the following: dusty plasma experiments in unmagnetized plasmas involved studying the thermodynamics of dust clusters by creating perfect two-dimensional monolayers. A novel method of injecting a controlled number of dust particles (for any number between 1 and 45, for example) allowed the formation and investigations of dust clusters having any prescribed number of dust particles (Kumar et al. Reference Kumar, Liu, Thakur, Thomas and Gopalakrishnan2024). In another set of experiments in unmagnetized and weakly magnetized plasmas (typically in a regime where the electrons are magnetized, but the ions are not), individual dust particles were optically trapped by counter propagating laser beams, which in turn allowed controlled transport of a dust particle in the background plasma (Ekanayaka et al. Reference Ekanayaka, Wang, Thakur and Thomas2024). This effectively opens up the possibility of using the microscopic dust particles as small probes to infer the local plasma electric fields. Studies of plasma chemistry based synthesis of both carbonaceous and titanium oxide nanoparticles have also been performed in both unmagnetized and weakly magnetized plasmas along with material characterization of the different phases of the titanium dioxide nanoparticles (Ramkorun et al. Reference Ramkorun, Chandrasekhar, Rangari, Thakur, Comes and Thomas2024a,Reference Ramkorun, Jain, Taba, Mahjouri-Samani, Miller, Thakur, Thomas and Comesb). Some of the more recent work in the high magnetic field experiment MDPX involve studies of shocks and instabilities during the expansion of laser ablated plasmas in a background magnetic field (White, Xu & Thakur Reference White, Xu and Thakur2024); understanding the dynamics of dust acoustic waves when the direction of the magnetic field and gravity are at oblique angles to each other (Williams et al. Reference Williams, Royer, Thakur, Thomas and Williams2025) and the associated dynamics of dust cloud compression as a function of the external magnetic field; understanding the effect of Zeeman splitting on coherence imaging spectroscopy technique that was subsequently used to measure edge flows and edge ion temperatures in the device W7-X stellarator in Germany (Kriete et al. Reference Kriete, Perseo, Gradic, Ennis, König and Maurer2024); and the morphology of field-aligned filaments due to pattern formation at high magnetic fields as a function of the effective ion magnetization (the ion Hall parameter) (Williams et al. Reference Williams, Thakur, Menati and Thomas2022).

3.4 The Phase Space Mapping Experiment (PHASMA)

The PHASMA is located at West Virginia University in Morgantown, WV.Footnote ⁶ It is participating in the Joint Call for the first time in 2024. It is designed to facilitate the measurement of three dimensional electron, ion and neutral velocity distributions using purely optical diagnostics in a three-dimensional experimental target volume (Shi et al. Reference Shi, Srivastav, Beatty, John, Lazo, McKee, McLaughlin, Moran, Paul and Scime2021). Additional purely optical diagnostics provide measurements of magnetic and electric fields as well as turbulent fluctuation spectra and electron density. Plasmas are created in PHASMA with two complementary plasma sources Stevenson et al. (Reference Stevenson, Gilbert, Good, Paul, Shi, Nirwan, Srivastav, Steinberger and Scime2024). The first is a steady-state helicon plasma source that generates plasma densities up to $10^{19}\ {\rm m}^{-3}$ at magnetic fields from 0 to 0.18 T. The second source is a pair of pulsed plasma guns generating merging flux ropes at densities up to $10^{19}\ {\rm m}^{-3}$ and at magnetic fields from 0 to 0.035 T. Working gases include hydrogen, helium, krypton, argon and xenon. The overall length of PHASMA is 4 m, with 1.5 m being the helicon source. The PHASMA includes arrays of motorized Langmuir, triple and magnetic probes that scan across the plasma radius at multiple axial positions. A three-dimensional tomographic array provides full three-dimensional reconstructions of the flux rope region. High speed, ${\sim }9 \times 10^5$ frames per second cameras are available for imaging of the plasma evolution and turbulence.

Completed recent experiments in PHASMA have focused on the evolution and stability of single magnetic flux ropes and the interactions of merging flux ropes undergoing magnetic reconnection. Single flux ropes exhibit an $m = 1$ kink instability with a current threshold of half of the Kruskal–Shafranov current limit, consistent with predictions for non-line tied flux ropes. Measurements of the helicity, paramagnetism and growth rate of the instability matched theoretical predictions and the kink instability also excited Alfvén waves in the plasma (Shi et al. Reference Shi, Srivastav, Beatty, John, Lazo, McKee, McLaughlin, Moran, Paul and Scime2021). The dual flux rope experiments examined the heating and energization of electrons in fully three-dimensional reconnection at spatial scales and time periods that are small enough that ions are not expected to participate in the strong guide field reconnection process (i.e. electron-only reconnection). Both push and pull type reconnection occur during the flux rope merger and the electron heating is localized around the separatrix, consistent with two-dimensional particle-in-cell (PIC) simulations of the reconnection. The measured gain in enthalpy flux is up to 70 % of the incoming magnetic energy. Cold electron beam features, possibly indicative of wave–particle interactions, appear in direct electron velocity distribution function (EVDF) measurements. The electron beam velocity matched the local electron Alfvén speed (Shi et al. Reference Shi, Srivastav, Barbhuiya, Cassak, Scime, Swisdak, Beatty, Gilbert, John and Lazo2022). Three-dimensional (3-D) measurements of the EVDF, obtained with a 3-D Thomson scattering system, found that the electron heating is preferentially parallel to the guide magnetic field and is localized to one separatrix. Through the anisotropic electron heating measurements, the primary electron energization mechanism was identified as being the parallel reconnection electric field. The anisotropic electron heating measurements were reproduced in a 2-D PIC simulation and were consistent with magnetosheath observations of electron-only reconnection in a strong guide field (Shi et al. Reference Shi, Scime, Barbhuiya, Cassak, Adhikari, Swisdak and Stawarz2023).

3.5 Wisconsin Plasma Physics Laboratory (WiPPL)

The WiPPL is a collaborative research facility located at the University of Wisconsin – Madison, in Madison, WI.Footnote ⁷ It includes two medium-scale devices, the Madison Symmetric Torus (MST) and the Big Red Ball (BRB), both of which participate regularly in the Joint Call. Approximately half of the available run time on both devices is dedicated to external projects. A major scientific theme of WiPPL research is studying the flow of energy between particles and fields in plasmas. Other common topics of research include self-organization, turbulence, magnetic reconnection, particle energization, dynamo activity, shocks and plasma stability.

The MST (Dexter et al. Reference Dexter, Kerst, Lovell, Prager and Sprott1991) is a toroidal machine which is the only device in the USA capable of producing reversed-field pinch (RFP) plasmas (Marrelli et al. Reference Marrelli, Martin, Puiatti, Sarff, Chapman, Drake, Escande and Masamune2021). It can also produce low-field ($B\leq 0.14$ T) and low edge safety factor ($0 < q(a) < 2$) tokamak plasmas. It features an active-feedback error-field correction system, a resonant magnetic perturbation system and a neutral beam injector. Both the toroidal and poloidal field circuits are driven inductively, either by a passive pulse-forming network or by a high-bandwidth, feedback-controlled programmable power supply system (Holly et al. Reference Holly, Chapman, McCollam and Morin2015). Key diagnostics include an 11-chord interferometer/polarimeter, fast Thomson scattering, impurity ion charge-exchange recombination spectroscopy, various X-ray detectors and various insertable probes.

For many years, local MST research focused on studying the RFP configuration as a fusion concept. Notably, an inductive current-profile control technique was used to boost energy confinement to values rivalling that found in tokamak devices of comparable size and field (Chapman et al. Reference Chapman, Almagri, Anderson, Brower, Caspary, Clayton, Craig, Den Hartog, Ding and Ennis2010). Recently, the programmable power supply system has enabled higher toroidal field and allowed for routine operation of MST as a tokamak. It was discovered that MST tokamak plasmas are surprisingly resistant to disruptive behaviour, with the capability of operating in steady conditions at low edge safety factor (Hurst et al. Reference Hurst, Chapman, Almagri, Cornille, Kubala, McCollam, Sarff, Sovinec, Anderson and Den Hartog2022) and high Greenwald fraction (Hurst et al. Reference Hurst, Chapman, Sarff, Almagri, McCollam, Den Hartog, Flahavan and Forest2024). Three-dimensional helical equilibria (e.g. saturated kink modes) have been studied in both the RFP and the tokamak (the quasi-single-helicity state (Boguski et al. Reference Boguski, Nornberg, Gupta, McCollam, Almagri, Chapman, Craig, Nishizawa, Sarff and Sovinec2021) and the density snake, respectively). The acceleration and confinement of fast, non-thermal electrons in both the RFP and tokamak configuration have been studied (DuBois et al. Reference DuBois, Almagri, Anderson, Den Hartog, Lee and Sarff2017; Munaretto et al. Reference Munaretto, Chapman, Cornille, DuBois, McCollam, Sovinec, Almagri and Goetz2020), as well as anomalous heating of ions during RFP sawtooth crashes (Magee et al. Reference Magee, Den Hartog, Kumar, Almagri, Chapman, Fiksel, Mirnov, Mezonlin and Titus2011). Several external groups have conducted diagnostic development work at MST, including advanced X-ray measurements using a camera with tuneable energy sensitivity (Delgado-Aparicio et al.  Reference Delgado-Aparicio, VanMeter, Barbui, Chellai, Wallace, Yamazaki, Kojima, Almagari, Hurst and Chapman2021) and an X-ray microcalorimeter (Eckart et al. Reference Eckart, Beiersdorfer, Brown, Den Hartog, Hell, Kelley, Kilbourne, Magee, Mangoba and Nornberg2021). Other external groups have studied relaxation events (Thuecks & McCollam Reference Thuecks and McCollam2022; Sellner et al. Reference Sellner, von der Linden, Himura, Reksoatmodjo, Sears, You, Almagri, McCollam, Reyfman and Rouda2024) and two-fluid physics (Himura et al. Reference Himura, Almagri, Sarff, Ashida, Inagaki, Fujiwara, Inoue, Sanpei, von der Linden and McCollam2024) using advanced probe designs.

The BRB (Cooper et al. Reference Cooper, Wallace, Brookhart, Clark, Collins, Ding, Flanagan, Khalzov, Milhone and Nornberg2014) is a spherical device with edge multipole cusp confinement using arrays of permanent magnets mounted to the inner wall, so that the confining magnetic field is localized to the edge, while the large-volume interior plasma can be unmagnetized, allowing for high values of plasma $\beta$. Exterior Helmholtz coils and/or mirror coils at the poles are used to apply large-scale fields. The two hemispheres can be easily separated to permit access to the interior, where internal coils and permanent magnets can be mounted. A range of plasma sources are available, including compact toroid injectors and plasma jets. Diagnosis is primarily accomplished using a wide and versatile set of insertable, translatable probes.

The Terrestrial Reconnection Experiment (TREX) is a configuration on the BRB which utilizes internal drive coils to force magnetic reconnection with an opposing background field (Olson et al. Reference Olson, Egedal, Clark, Endrizzi, Greess, Millet-Ayala, Myers, Peterson, Wallace and Forest2021). Here, the absolute reconnection electric field is set by the external drive, but the normalized reconnection rate is shown to be dependent on the system size. With a new cylindrical drive system, TREX is now capable of reaching large Lundquist numbers of $S\sim 10^5$, accessing a regime where kinetic effects such as electron pressure anisotropy are expected to develop and heavily influence the dynamics of the electron diffusion region (Gradney et al. Reference Gradney, Egedal, Barnhill, Flores-García, Greess, Kuchta, Olson, Wallace, Yu and Forest2023). Using a similar coil configuration as TREX to drive supercritical perpendicular shocks, the full structure of the plasma–piston coupling was resolved in experiments on the BRB for the first time (Endrizzi et al. Reference Endrizzi, Egedal, Clark, Flanagan, Greess, Milhone, Millet-Ayala, Olson, Peterson and Wallace2021). A novel plasma equilibrium in the high-$\beta$, Hall regime has been created, producing a centrally peaked, high Mach number Couette flow driven by drawing large currents across a weak, uniform magnetic field (Flanagan et al. Reference Flanagan, Milhone, Egedal, Endrizzi, Olson, Peterson, Sassella and Forest2020). A specialized laboratory model based on a rapidly rotating plasma magnetosphere was also created to study the dynamics of the Parker spiral, the spiralling magnetic structure pervading the Solar System (Peterson et al. Reference Peterson, Endrizzi, Beidler, Bunkers, Clark, Egedal, Flanagan, McCollam, Milhone and Olson2019, Reference Peterson, Endrizzi, Clark, Egedal, Flanagan, Loureiro, Milhone, Olson, Sovinec and Wallace2021). Several external projects on the BRB have utilized the compact torus (CT) injectors, which launch a spheromak-like plasma structure. The CT plasmas have been used to characterize fast magnetosonic waves generated along a background field (Chu et al. Reference Chu, Langendorf, Olson, Byvank, Endrizzi, LaJoie, McCollam and Forest2023), as well for studying the dynamics of a scaled interplanetary coronal mass ejection in the laboratory (Bryant et al. Reference Bryant, Young, LeFevre, Kuranz, Olson, McCollam and Forest2024a,Reference Bryant, Young, LeFevre, Kuranz, Olson, McCollam, Kuchta and Forestb).

3.6 Bryn Mawr Experiment (BMX)

This facility is located at Bryn Mawr College in Bryn Mawr, PA.Footnote ⁸ It is designed to generate long plumes of turbulent magnetized plasma to investigate magnetized turbulence as well as interactions between plasma flows and targets (Cartagena-Sanchez, Carlson & Schaffner Reference Cartagena-Sanchez, Carlson and Schaffner2022). Situated at a liberal-arts women's institution, BMX offers undergraduate students opportunities for hands-on experimental plasma work and the engagement of groups historically underrepresented in plasma. Initial work has focused on exploring the dissipation scales found in the turbulent plasma, the scale at which magnetic and flow energy begins to transition into thermal energy. Using correlation measurements of magnetic field fluctuations along the flow axis, the Taylor microscale was measured to be approximately 4 cm, approximately 1/6th scale of the outer diameter of the machine (Cartagena-Sanchez et al. Reference Cartagena-Sanchez, Carlson and Schaffner2022). Continued study on the experiment will focus on interactions between the turbulent flow and both insulating and magnetic targets.

3.7 Facility for Laboratory Reconnection Experiments

This facility is located at the Princeton Plasma Physics Laboratory in Princeton, NJ.Footnote ⁹ The Facility for Laboratory Reconnection Experiments (FLARE) is a mid-sized device specifically designed to study magnetic reconnection in regimes that are directly relevant to space and astrophysical plasmas. FLARE's design aims to achieve high Lundquist numbers and large system sizes normalized to kinetic scales, ensuring that it can experimentally access the multiscale reconnection physics governed by the plasmoid instability. This capability is crucial for understanding the fundamental processes that drive reconnection in natural plasma environments, such as those found in solar flares and the Earth's magnetosphere. Following a significant power system upgrade, FLARE is set to be commissioned in 2025 and will operate as a collaborative research facility. This status will allow researchers from various institutions to conduct experiments and contribute to the broader scientific understanding of magnetic reconnection. The facility's ability to reproduce and study these critical plasma phenomena under controlled conditions makes it an invaluable asset to the field of plasma physics, providing insights that bridge the gap between theoretical models and real-world observations. Through its advanced experimental capabilities, FLARE is poised to make significant contributions to our knowledge of space and astrophysical plasma dynamics.

3.8 Space Physics Simulation Chamber

The NRL Space Physics Simulation Chamber (SPSC) is located at the US Naval Research Laboratory in Washington, D.C.Footnote ¹⁰ It is used to conduct investigations into the dynamic behaviour of plasmas scaled to near-Earth space conditions of interest (Amatucci et al. Reference Amatucci, Blackwell, Walker, Gatling and Ganguli2005). Space Chamber projects include the basic physics driving plasma waves and instabilities in the ionosphere and magnetosphere, the development of innovative diagnostics for space and laboratory use, space situational awareness investigations and radiation belt dynamics. A wide variety of in situ and non-invasive plasma diagnostics are available and the machine is fully automated to support long-duration experiments that can run 24 hours a day. The 5 m long main Space Chamber section is equipped with dual 3-axis translation stages, providing millimetre precision positioning of experimental hardware and diagnostics.

3.9 Swarthmore Spheromak Experiment (SSX)

This facility is located at Swarthmore College in Swarthmore, PA.Footnote ¹¹ It is designed to study plasma turbulence and magnetic reconnection in the MHD regime (Brown & Schaffner Reference Brown and Schaffner2015). In the present configuration, magnetized plasma rings are injected at either end, the rings relax to twisted magnetic states and merge at the midplane at high velocity. Magnetic structure, ion temperature and electron density are measured at the midplane. Currently, SSX research is focused on conducting statistical studies of 3-D magnetic reconnection.

4.1 PlasmaPy

The mission of the PlasmaPy projectFootnote ¹² is to foster the growth of a fully open source software ecosystem for plasma research and education, in alignment with the mission of MagNetUS. The PlasmaPy core package contains functionality for representing particles, calculating plasma parameters, finding plasma wave dispersion relationships and analysing data from plasma diagnostics, such as Thomson scattering, Langmuir probes and charged particle radiography (Murphy et al. Reference Murphy, Everson, Stańczak-Marikin, Heuer and Kozlowski2024). As an open source project, all are welcomed to contribute so long as they follow the code of conduct. PlasmaPy's online documentation describes how to use functionality along with the underlying physics. The PlasmaPy team hosted a live coding tutorial immediately following the annual MagNetUS meeting in 2023 as well as a summer school in 2024 as opportunities to learn how to use and contribute to PlasmaPy. PlasmaPy can become a platform for sharing software needed across MagNetUS.

4.2 Plasma Science Virtual Laboratory

Discussions at MagNetUS meetings led to the idea to develop a virtual simulation ‘facility’ which would function similarly to the experimental facilities participating in the Joint Call. Here, users would have an easy-to-use interface to perform simulations without the need to compile or run the codes themselves, thus, reducing barriers that limit access to numerical tools. Preliminary work has led to adding such capabilities to the Plasma Science Virtual Laboratory (VLab)Footnote ¹³ (Abeysinghe et al. Reference Abeysinghe, Smith, Wang, Juno, Mccall, Pierce and Shephard2023) Science Gateway, which provides a simple, web browser-based interface to perform simulations using the Gkeyll simulation framework (Hakim Reference Hakim2024). Through the VLab, users can run pre-defined Gkeyll multi-moment fluid (Hakim, Loverich & Shumlak Reference Hakim, Loverich and Shumlak2006; Wang et al. Reference Wang, Hakim, Bhattacharjee and Germaschewski2015), continuum kinetic (Juno et al. Reference Juno, Hakim, TenBarge, Shi and Dorland2018; Hakim & Juno Reference Hakim and Juno2020) and gyrokinetic (Shi et al. Reference Shi, Hammett, Stolzfus-Dueck and Hakim2017; Mandell et al. Reference Mandell, Hakim, Hammett and Francisquez2020) simulations with certain user adjustable parameters on National Science Foundation (NSF) ACCESS supplied high-performance computing resources. The user can then plot the simulation data or download the full simulation output. VLab is actively being expanded to provide resources for modelling MagNetUS devices, such as the LAPD, DIII-D and MDPX.

4.3 bapsflib

BaPSF's software library, bapsflib, is an open-source Python package designed to facilitate the analysis and interpretation of data from the BaPSF at UCLA.Footnote ¹⁴ The primary goal of bapsflib is to provide a standardized user interface for the HDF5 data files generated at BaPSF. This standardized interface eases data access and allows researchers to more quickly proceed with data analysis. bapsflib standardization includes organization of the metadata associated with a data run, providing functionality for data read out, providing functionality to combine digitized data with control data (like positional data, antenna drive frequencies, etc.) and more. By providing bapsflib, BaPSF makes legacy data runs (pre-2018) accessible and standardized, as well as making data access resilient to infrastructure upgrades to the LAPD. Through bapsflib, UCLA continues to enhance the accessibility and usability of plasma data, fostering collaborative research efforts and accelerating advancements in plasma science.

4.4 OMFIT

OMFIT (one modelling framework for integrated tasks) is a highly versatile and collaborative software platform designed to facilitate the integrated modelling and analysis of fusion experiments (Meneghini et al. Reference Meneghini, Smith, Lao, Izacard, Ren, Park, Candy, Wang, Luna and Izzo2015).Footnote ¹⁵ Developed to streamline the workflow of fusion research, OMFIT enables the seamless coupling of various simulation codes and the integration of diverse datasets, providing a comprehensive tool for interpreting and predicting plasma behaviour. Its modular architecture allows users to incorporate different physics models, perform data analysis and visualize results within a single, cohesive environment. OMFIT supports a wide array of fusion-related tasks, including equilibrium reconstruction, transport simulations, stability analysis and scenario development. By fostering interoperability and collaboration among researchers, OMFIT enhances the efficiency and accuracy of fusion studies, driving advancements in the understanding and optimization of plasma confinement and control. This platform is particularly valuable for its role in bridging the gap between experimental data and theoretical models, thereby accelerating the development of viable fusion energy solutions (Meneghini & Lao Reference Meneghini and Lao2013). Among MagNetUS facilities, OMFIT is most extensively used at DIII-D.