1.1. Scientific motivation for a new facility

One of the major difficulties in studying space and astrophysical plasmas is characterizing energy and momentum transport across the broad range of scales of dynamical importance. For example, in galactic dynamics, there are roughly twelve orders of magnitude between the ion-scale fluctuations in the galactic disc and the much larger scales on which the energy transfer processes between the thermal plasma and cosmic rays operate (Brunetti & Jones Reference Brunetti and Jones2014). Similar scale problems exist in our local heliosphere, where large-scale fluctuations driven by solar rotation are six orders of magnitude larger than small-scale fluctuations on electron gyration periods that terminate the turbulent cascade (Kiyani, Osman & Chapman Reference Kiyani, Osman and Chapman2015). Understanding the mesoscale processes that determine the energy partition between thermal plasma species and couple the small- and large-scale dynamics is critical for making progress on open questions in both space and astrophysical systems.

The processes that are most critical to understand, and currently most poorly understood, are those occurring in high-beta (thermal pressure is greater than or approximately equal to magnetic pressure), magnetized, weakly collisional plasmas (Kunz et al. Reference Kunz2019). These include, but are not limited to:

1. (i) Instabilities not only produce electromagnetic fluctuations but also constrain these same fluctuations by scattering particles and modifying the plasma’s energy and momentum transport. These processes are important in a variety of astrophysical environments. In the solar wind, the role of pressure-anisotropy-driven instabilities in constraining the fluctuations present is well established (Bale et al. Reference Bale, Kasper, Howes, Quataert, Salem and Sundkvist2009). Outside of the heliosphere, instabilities play a large role in a number of astrophysical systems, including accretion discs at the heart of galaxies, galaxies themselves and the intracluster medium (Balbus & Hawley Reference Balbus and Hawley1991; Quataert, Dorland & Hammett Reference Quataert, Dorland and Hammett2002; Quataert Reference Quataert2008; Kunz et al. Reference Kunz, Schekochihin and Stone2014, Reference Kunz, Jones and Zhuravleva2022). Instabilities also play a large role in cosmic-ray energization near supernova remnants (Bell Reference Bell2004), the coupling between the thermal plasma in the galactic disc and cosmic rays (Kulsrud & Pearce Reference Kulsrud and Pearce1969), shock heating throughout the universe (Spitkovsky Reference Spitkovsky2008; Caprioli & Spitkovsky Reference Caprioli and Spitkovsky2013; Wilson et al. Reference Wilson, Sibeck, Breneman, Contel, Cully, Turner, Angelopoulos and Malaspina2014, Reference Wilson, Sibeck, Turner, Osmane, Caprioli and Angelopoulos2016) and potentially the generation of radio halos (Brunetti & Jones Reference Brunetti and Jones2014). Relevant instabilities include firehose and mirror instabilities (Gary et al. Reference Gary, Skoug, Steinberg and Smith2001; Kasper, Lazarus & Gary Reference Kasper, Lazarus and Gary2002; Hellinger et al. Reference Hellinger, Trávníček, Kasper and Lazarus2006; Schekochihin et al. Reference Schekochihin, Cowley, Kulsrud, Rosin and Heinemann2008; Rosin et al. Reference Rosin, Schekochihin, Rincon and Cowley2011), heat-flux and gradient-driven instabilities (Komarov et al. Reference Komarov, Churazov, Kunz and Schekochihin2016; Komarov et al. Reference Komarov, Schekochihin, Churazov and Spitkovsky2018; Riquelme, Quataert & Verscharen Reference Roberg-Clark, Drake, Reynolds and Swisdak2016, Reference Roberg-Clark, Drake, Reynolds and Swisdak2018; Verscharen Reference Riquelme, Quataert and Verscharen2016) and streaming instabilities (Bell Reference Bell2004; Amato & Blasi Reference Amato and Blasi2009), among others.

2. (ii) Turbulence is a major channel of energy transfer in many space and astrophysical systems. Understanding the details of how turbulence transfers energy from scale to scale and the processes by which it ultimately transfers energy to the particles is critical for a number of open questions. The resulting energy and momentum transport affects everything from the state of the turbulent solar wind at Earth (Breech et al. Reference Breech, Matthaeus, Cranmer, Kasper and Oughton2009; Howes Reference Howes2010) to the amount and type of radiation emitted from astrophysical objects such as accretion discs (The Event Horizon Telescope Collaboration et al. 2019a , b , 2021). Furthermore, turbulence affects the evolution of large-scale structures everywhere from our heliosphere (Tu & Marsch Reference Tu and Marsch1995; Verscharen, Klein & Maruca Reference Verscharen, Klein and Maruca2019; Richardson et al. Reference Richardson, Burlaga, Elliott, Kurth, Liu and von Steiger2022) to more distant galaxies and their surrounding circumgalactic media (Tumlinson, Peeples & Werk Reference Tumlinson, Peeples and Werk2017; Ji et al. Reference Ji2020; Lochhaas et al. Reference Lochhaas2023). Due to the very large-scale separation between the turbulent dissipation and the macroscopic evolution, widely used fluid models of these large-scale systems (Tóth et al. Reference Tóth2012; Thomas & Pfrommer Reference Thomas and Pfrommer2022; Talbot et al. Reference Talbot, Pakmor, Pfrommer, Springel, Werhahn, Bieri and van de Voort2024) use effective heat conduction and viscosity terms to approximate the energy and momentum transport due to turbulent dissipation. The underlying turbulent dissipation model chosen can significantly affect the observed behavior of the system (e.g. Chael et al. Reference Chael, Rowan, Narayan, Johnson and Sironi2018, Reference Chael, Narayan and Two-temperature2019). The ambient, turbulent magnetic fluctuations in these systems can also affect the trajectory of cosmic rays, the most energetic particles in the universe, and can impact our understanding of where these fast, charged particles originate (Owen et al. Reference Owen, Wu, Yoshiyuki Inoue and Mitchell2023).

To enhance our understanding of energy and momentum transport in the aforementioned space and astrophysical systems, a plasma device capable of achieving collisionless conditions while being magnetized with high plasma beta is necessary. Basic plasma science experiments have had success in studying astrophysical phenomena where one or two of the conditions (collisionless, magnetized, and high beta) are met (Keiter et al. Reference Keiter, Scime, Balkey, Boivin, Kline and Gary2000; Brown & Schaffner Reference Brown and Schaffner2014; Schaffner, Wan & Brown Reference Schaffner, Wan and Brown2014; Dorfman & Carter Reference Dorfman and Carter2016; Endrizzi et al. Reference Douglass Endrizzi, Clark, Flanagan, Greess, Milhone, Millet-Ayala, Olson, Peterson, Wallace and Forest2021; Peterson et al. Reference Peterson2021; Schroeder et al. Reference Schroeder, Howes, Kletzing, Skiff, Carter, Vincena and Dorfman2021; Ji et al. Reference Ji2023; Bose et al. Reference Bose, TenBarge, Carter, Hahn, Ji, Juno, Savin, Tripathi and Vincena2024). However, existing experiments (e.g. Forest et al. Reference Forest2015; Gekelman et al. Reference Gekelman2016) struggle to achieve all three conditions simultaneously, leaving a key gap in our approach to solving the problems mentioned above. Recent community planning documents have therefore envisioned a next generation laboratory facility to tackle these problems (Carter et al., Reference Carter2020; Milchberg & Scime, Reference Milchberg and Scime2020; Baalrud et al., Reference Baalrud, Ferraro, Garrison, Howard, Kuranz, Sarff and Solomon2020; Dorfman et al., Reference Dorfman2023; National Academies of Sciences, Engineering, and Medicine 2024). Unlike spacecraft, laboratory experiments can take multi-point measurements of a controlled, reproducible plasma (Howes Reference Howes2018; Lichko et al. Reference Lichko, Endrizzi, Juno, Olson, Dorfman and Young2020, Reference Lichko2023). Such experiments can therefore complement and extend the utility of spacecraft in exploring the multi-scale and multi-dimensional physics that occurs in space and astrophysical systems. Thus, the proposed device will take advantage of these unique capabilities of laboratory experiments to enable novel plasma science experiments with broad relevance to space and astrophysical plasmas.

Table 1.

Machine requirements: key dimensionless parameter requirements that existing facilities struggle to satisfy which will open up a new physical regime for studies of energy and momentum transport via turbulence and instabilities.

1.2. Goals of the planning process

To tackle this problem, the CHIMERAS (Collisionless HIgh-beta Magnetized Experiment Researching Astrophysical Systems) project working group has been formed under the auspices of MagNetUS, which is a network comprising several basic plasma science facilities and their collaborators. The working group consists of 30+ scientists from various parts of the community (space observation, numerical simulations, theory, and laboratory experiments) and is actively defining the necessary technical requirements to design an experimental facility to address the science goals in § 1.1. Our planning process has two major aims:

1. (i) Design a device to create a $\beta _i = 8 \pi n T_i / B^2 \gtrsim 1$ , collisionless, magnetized plasma in the laboratory for the first time. This new regime will enable novel plasma science experiments with broad relevance to space and astrophysical plasmas. We will for the first time be able to study astrophysically relevant collisionless instabilities and magnetized plasma turbulence.

2. (ii) Nurture the budding investigator network working on the device by involving researchers from different parts of the field (space observation, computer simulations, theory and laboratory experiments) and different career stages (including graduate students and postdocs) in the above discussions. This broad array of expertise will expose participants to subject areas and research techniques with which they may not be familiar.

A summary of the key dimensionless parameter requirements necessary to address our first aim is given in table 1. The high-beta condition is necessary because the space and astrophysical environments this machine aims to emulate are typically $\beta _i \gtrsim 1$ , and the onset of several of the targeted instabilities is dependent on $\beta _i$ . The collisionless condition comes from the two-fluid Alfvén wave dispersion relation (Mallet et al. Reference Mallet, Dorfman, Abler, Bowen and Chen2023); to explore kinetic scales, we wish to minimize Alfvén wave damping in the regime where the waves are dispersive. Since the frequency of Alfvén waves in the device is expected to range from a fraction of the ion cyclotron frequency ( $f_{ci}$ ) to slightly less than $f_{ci}$ , we will sometimes write this criterion in terms of the ratio of the electron-ion collision frequency to the ion cyclotron angular frequency ( $\nu _{ei}/\omega _{ci}$ ). The need to fit magnetohydrodynamic (MHD) Alfvén waves in the device gives rise to the magnetized condition; this leads to different conditions for machine length along the background magnetic field $L_\parallel$ and the machine diameter perpendicular to the field $L_\perp$ . The relevant conditions are in terms of the ion gyroradius $\rho _i$ and the ion skin depth $d_i$ . We need to resolve perpendicular wavenumbers ( $k_\perp$ ) that satisfy $k_\perp \rho _i \sim 1$ in order to capture the relevant anisotropy-driven instability physics. Meanwhile, we need to be able to launch Alfvén waves at perpendicular scales larger than both $\rho _i$ and $d_i$ in the turbulence experiments in order to avoid complications due to the presence of dispersive effects and Hall effects, respectively (Mallet et al. Reference Mallet, Dorfman, Abler, Bowen and Chen2023). Since the smallest $k_\perp$ that can fit in the device will be $2\pi /L_\perp$ , the factor of fifty is the minimum necessary to enable both the instability and the turbulence experiments, as it allows for $k_\perp \rho _i \gtrsim 0.13$ (or $k_\perp d_i \gtrsim 0.13$ ). The scale requirement in the parallel direction allows a low-frequency Alfvén wave ( $\omega \ll {\omega _{ci}}$ ) to fit in the device; this may be seen by noting that the MHD Alfvén wave dispersion relation can be written as $k_\parallel d_i = \omega /\omega _{ci}$ . The device will therefore be large enough to contain counter-propagating, low-frequency Alfvén waves for the turbulence experiments and large enough to resolve low-frequency Alfvén waves that result from the instabilities.

2.1. Preliminary set of dimensionless parameters

Our preliminary set of parameters for both the instability (A) and turbulence (B) experiments are outlined in table 2 (dimensional) and table 3 (dimensionless). These parameters are optimized around the requirements in table 1 and assume that the experiments will be conducted in hydrogen plasma. The optimization process is illustrated in figure 1. The red and blue shadings indicate different levels of $\beta _i$ and $\nu _{ei}/\omega _{ci}$ , respectively; the regions with darker shading are better able to meet each of the first two requirements in table 1. In dimensional terms, the primary difference between the two experimental set-ups is the magnetic field strength, $B_0$ ; this difference is because the high-beta condition is not strictly necessary for the turbulence experiments (set-up B).

Table 2.

Preliminary set of dimensional parameters in hydrogen plasma for both high-beta collisionless instabilities (A) and solar wind magnetized plasma turbulence (B): parameters are plasma density, electron temperature, ion temperature, background magnetic field, driven Alfvén wave frequency, ion cyclotron frequency, ion skin depth, ion gyroradius, electron–ion collision frequency, driven Alfvén parallel wavelength, chamber diameter and chamber length. Note that the ion cyclotron frequency and Alfvén wave frequency are both ordinary frequencies, while the electron–ion collision frequency is an angular frequency.

Table 3.

Preliminary set of dimensionless parameters in hydrogen plasma for both high-beta collisionless instabilities (A) and solar wind magnetized plasma turbulence (B): parameters are the ratio of electron thermal speed to Alfvén speed, parallel wavenumber corresponding to $f_0$ from table 2 times ion skin depth, the ratio of collisionality to ion cyclotron angular frequency $({\omega _{ci}} =2\pi f_{ci}$ ), electron beta and ion beta.

Figure 1.

Location of set-ups A and B in parameter space. Blue shading indicates different levels of $\beta _i$ while red shading indicates different levels of $\nu _{ei}/{\omega _{ci}}$ . Black lines show the value of $L_\perp =50 \max (d_i,\rho _i)$ for set-ups A and B. (a) Location of set-up A in $n$ - $T$ parameter space. (b) Location of set-up B in $n$ - $T$ parameter space. (c) Location of both set-ups in $B$ - $T$ parameter space. Note that $L_\perp =3.62$ m everywhere to the right of the $\beta _i=1$ line in (c), not just on black dashed line.

According to the requirements in table 1 and parameters in table 2, a large chamber with diameter $L_ \bot \sim 50\max \left ( {{d_i},{\rho _i}} \right )=7.25 \,\textrm {m}$ and length $L_ \parallel \sim 100\max \left ( {{d_i},{\rho _i}} \right )=14.5 \,\textrm {m}$ will work for studying both turbulence as well as kinetic instabilities in a magnetized, collisionless, high ion beta plasma. Generating high-density plasma ( $n \gt {10^{13}}\,{\textrm {c}}{{\textrm {m}}^{ - 3}}$ ) in a large chamber is challenging; thus, we use this as our upper limit on plasma density, which effectively sets the lower limit on the device size.Footnote ¹ These limits were calculated assuming a hydrogen plasma. A helium plasma would allow for increased diagnostic flexibility (see § 3.1.2), but would increase the scale (in dimensional units) that corresponds to $k_\perp \rho _i = 1$ and thus necessitate a larger vessel size.

2.2. Necessity of a source-target geometry

To access new plasma parameter regimes in which the plasma is magnetized, collisionless, and high $\beta _i$ , it was the conclusion of the workshop discussion that the configuration of the experiment would require a geometry in which a source plasma would fill a target chamber. This particular configuration arose from the key constraint in generating both large $\beta _i$ and a magnetized plasma. Currently operating experiments which have $\beta _i\gt 1$ are too small to achieve the magnetized condition; when the plasma’s own magnetic field is weak enough to achieve high beta, the ion gyroradius is often comparable to, or larger than, the system size (Bott et al. Reference Bott2021; Endrizzi et al. Reference Douglass Endrizzi, Clark, Flanagan, Greess, Milhone, Millet-Ayala, Olson, Peterson, Wallace and Forest2021; Meinecke et al. Reference Meinecke2022). Furthermore, any plasma created in a single chamber which has plasma pressure greater than magnetic pressure will rapidly expel the magnetic field; thus, the plasma will not remain magnetized.

Correspondingly, we must engineer a system in which an initially confined, magnetized, collisionless plasma source is allowed to expand into a secondary target chamber so that as the plasma expands, the plasma naturally enters the conditions desired due to its own dynamical evolution. To reduce the loss of plasma to the walls and improve confinement time, the walls of the target chamber can be lined with permanent magnets in either a line-cusp or a broken line-cusp configuration (Limpaecher & MacKenzie Reference Limpaecher and MacKenzie1973; Gekelman & Stenzel Reference Gekelman and Stenzel1975; Leung, Samec & Lamm Reference Leung, Samec and Lamm1975; Forest et al. Reference Forest2015). Additionally, fusion-like temperatures can be realized in the source chamber through combinations of electron cyclotron resonant heating and neutral beam injection, which would push the plasma further into the collisionless regimes necessary to study the kinetic plasmas commonly observed in astrophysical systems.

This particular configuration has a number of added benefits for the physics goals we seek to address with this new facility. For example, the expansion of the plasma in this system is analogous to the expansion of the solar wind. This feature will allow the community to study how the effects of expansion on the distribution function may be limited by plasma instabilities and how the transport of momentum and heat in an expanding plasma may be modified by collisionless processes. Further, a source region can be constructed which provides a large degree of flexibility for the temperature of the plasma in the target chamber. This flexibility will allow for additional possible diagnostic options. For example, the proposed turbulence configuration can tolerate a range of $\beta _i$ , so operating at lower temperature (lower $\beta _i$ ) is feasible. Although this choice will increase the collisionality, figure 1 shows there is significant flexibility in maintaining the collisionless condition. Decreasing the temperature by a factor of four will still keep the ratio of $\nu _{ei}/\omega _{ci} \lt 0.1$ , thus minimizing the amount of collisional damping expected.

2.3. Diagnostic/measurement requirements

The key quantities to be measured are density ( $n$ ), parallel ( $\parallel$ ) and perpendicular ( $\perp$ ) components of the electron ( $T_{e}$ ) and ion temperature ( $T_{i}$ ), as well as fluctuations in density ( $\delta n$ ), magnetic field ( $\delta B$ ) and bulk ion velocity ( $\delta v$ ) associated with waves and instabilities.Footnote ² The fluctuating quantities must be measured with sufficient spatial and temporal resolution to effectively study turbulence and instabilities. For the turbulence experiment, the parallel wavelength ( $\lambda _{\parallel }$ ) of the excited Alfvén waves is expected to be comparable to or longer than the perpendicular wavelength ( $\lambda _{\perp }$ ); thus the latter sets the limit for spatial resolution. For both the turbulence and ion-scale instability experiments, the key kinetic physics, e.g. the largest ion damping rates of turbulent fluctuations or the largest growth rates of unstable ion modes, is expected to occur around $k_{\perp } \rho _{i} \sim 1$ . Therefore, a spatial resolution smaller than ${\sim}\rho _{i}$ is desired for set-ups A and B. With this resolution and the desired vessel volume (table 1), we also have multiple decades of resolved scales for the turbulence studies (from ${\sim}3.6$ m driving scales down to ${\lesssim}3.6$ cm sub- $\rho _i$ scales). The time resolution for the turbulence experiment is set by the requirement to measure oscillating quantities associated with an Alfvén wave ( $\delta B$ , $\delta v$ , and at small scales $\delta n$ ). The frequency of the excited Alfvén waves is expected to range from a fraction of the ion cyclotron frequency ( $f_{ci}$ ) to slightly less than $f_{ci}$ . For the experiments on anisotropy driven ion instabilities, the bulk of the measurements are expected to be made at $f_{ci}$ scales. Since $f_{ci}$ is the highest frequency that needs to resolved, we require diagnostics that can sample data at rates at least ${\sim}10\,f_{ci}$ .

Typically, the aforementioned quantities are measured with good spatial and temporal resolution in basic plasma physics experiments using in situ probes. However, we will not be able to extensively use in situ probes, as the high heat and particle flux at the densities and temperatures in our proposed experiments (see tables 2 and 3) will significantly reduce the lifetime of the probes. An alternative solution is to adopt optical diagnostics developed by the fusion community as much as possible. These diagnostics do not require in situ components.

In fact, because several of the scientific questions CHIMERAS seeks to address require measurements of the particle distribution functions of electrons and ions, optical diagnostics will be a key component of the experimental measurement suite. Techniques such as laser-induced fluorescence (Boivin & Scime Reference Boivin and Scime2003; Gorbunov et al. Reference Gorbunov, Mukhin, Berik, Vukolov, Lisitsa, Kukushkin, Levashova, Barnsley, Vayakis and Walsh2017) and Thompson scattering (Ghazaryan et al. Reference Ghazaryan, Kaloyan, Gekelman, Lucky, Stephen Vincena, Pribyl and Niemann2022; Kaur et al. Reference Kaur2024) have been routinely deployed in fusion and other laboratory plasmas, and recent demonstrations of these techniques to reconstruct three-dimensional distribution functions (Shi & Scime Reference Shi and Scime2023; Gilbert, Steinberger & Scime Reference Gilbert, Steinberger and Scime2024) are extremely promising. It has now been demonstrated that not only can these diagnostics provide spatially resolved measurements of the bulk non-ideal physics, such as the temperature anisotropy of electrons and ions,Footnote ³ but these diagnostics also offer resolved measurements of detailed non-Maxwellian features of the distribution function (Shi et al. Reference Shi, Prabhakar Srivastav, Cassak, Scime and Swisdak2022). Measurements of this fidelity allow for detailed phase-space analysis that may be used to identify the details of the energy transfer in collisionless plasmas. For example, measurements of ion temperature anisotropy in space plasmas have previously been related to ion cyclotron damping (Kasper et al. Reference Kasper, Maruca, Stevens and Zaslavsky2013) and stochastic heating (Chandran et al. Reference Chandran, Verscharen, Quataert, Kasper, Isenberg and Bourouaine2013). Characterization of energy transfer using the field-particle correlation technique (Klein & Howes Reference Klein and Howes2016; Howes, Klein & Li Reference Howes, Klein and Li2017; Schroeder et al. Reference Schroeder, Howes, Kletzing, Skiff, Carter, Vincena and Dorfman2021) is a lower priority for CHIMERAS due to the challenges measuring fluctuating electric fields discussed in § 3.1.2.

Table 4 shows a list of possible diagnostics that may meet the goals of our experiments after suitable modifications. For some of the diagnostics, such modifications will require further research and development. This point will be discussed in § 3.1.2.

Table 4.

Promising diagnostics that can be used to measure key physical parameters. Important open questions in the ‘remarks’ column are elaborated on in § 3.1.2.

2.4. Training and professional development

The working group also understands the importance of training the next generation of plasma researchers on plasma source development, cutting-edge diagnostics, data analysis techniques and high-fidelity modeling that are crucial to the broader field of laboratory experiments for space and astrophysical plasmas. This unique facility will bring in scientists from different plasma communities, which will expose students and postdoctoral researchers to a broad range of interdisciplinary plasma topics. This synergy provides the perfect platform to serve as a training ground for young scientists. Moreover, this facility will also serve as a center for extensive plasma outreach and public engagement. The facility will bring together plasma scientists from all parts of the US, including several EPSCoR states, allowing us to implement outreach programs in diverse geographical locations and organize more targeted programs for primarily undergraduate institutes and minority serving institutes, in addition to pursuing research experiences for undergraduates and research experiences for teachers programs. Finally, leveraging current working group members’ connections, we plan to work with other organizations such as the Coalition for Plasma Science and MagNetUS (a network of users of the magnetized plasma collaborative research facilities) and the education and outreach committees of the American Physical Society – Division of Plasma Physics, the Princeton Plasma Physics Laboratory, Oak Ridge National laboratory, along with federal agencies such as the National Science Foundation (NSF), Department of Energy (DOE) and the National Aeronautics and Space Administration (NASA) to organize summer schools and hands-on training workshops for graduate, undergraduate and high school students and teachers. This unique combination of a cutting-edge research and educational platform will simultaneously serve the missions of workforce development and public engagement.

3.1. Outstanding challenges

Discussions at the workshops allowed the working group to more precisely define the outstanding challenges which must be answered before the construction of a device can begin. These questions fall into three categories: (i) plasma evolution and wave drive; (ii) diagnostic development and choice of gas species; and (iii) vessel size and shape.

3.2. Dissemination of workshop results and next steps

The working group recognizes the need for community and government support if a device like the one we envision is to become a reality. Our first action toward building the necessary support is to disseminate workshop results to the broader astrophysics, solar physics, heliophysics and plasma physics communities. Members of the working group provided a progress report at the 2024 American Physical Society Division of Plasma Physics conference during the associated MagNetUS reception. As the project matures the working group will increase their presence at other conferences, including but not limited to meetings of the American Astronomical Society, American Geophysical Union (AGU) and Solar Heliospheric and Interplanetary Environment workshop.

The working group plans to host semi-annual workshops after the annual MagNetUS and AGU Fall meetings, respectively, to further develop the device concept and increase community engagement with and investment in the project. Our next steps are to further investigate the current state of the art in plasma diagnostic capabilities and plasma turbulent driver technology and to design a pre-prototype device capable of generating and maintaining a collisionless plasma. Potential research projects that support the design of a next-generation device and could be immediately proposed for funding will be discussed; such projects include but are not limited to diagnostic development efforts (such as those identified in § 3.1.2), development and testing of drivers for turbulence experiments and simulations to better establish the physics of the source and plasma expansion into the target chamber to test and refine the device design. We plan to seek federal and private funding to enable dedicated design and development work and accelerate the current pace of progress.