Measuring the equations of state in a relaxed magnetohydrodynamic plasma

Kaur, Manjit; Barbano, L. J.; Suen-Lewis, E. M.; Shrock, J. E.; Light, Adam; Brown, M. R.; Schaffner, David

doi:10.1103/physreve.97.011202

Cited by 11 publications

(18 citation statements)

References 22 publications

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“…The goal of Swarthmore was to explore whether the helical Taylor state could become a suitable target for compression. Under this project, the team sought to measure the equations of state for a Taylor state by carrying out compression and heating experiments by creating a parcel of magnetized plasma, compressing it against the end wall of a chamber, and measuring plasma density, temperature, and magnetic field during compression [75], [76]. The team conducted their experiments on the existing Swarthmore Spheromak Experiment device (SSX), which has an advanced diagnostic suite and the capability to perform 100 experiments per day, which enabled rapid progress in understanding the behavior of these plasma plumes and illuminating their potential for use as new targets in the pursuit of fusion reactors.…”

Section: Exploratory Concepts Lawrence Berkeley National Laboratomentioning

confidence: 99%

“…In this work the team found that the parallel component of the Chew, Goldberger, and Low (CGL) equation of state was the best fit for the behavior of the Taylor state. [75] As a result, our understanding of the state of the art for Taylor state compression was advanced. The Swarthmore team observed that Taylor states have very different flux loss behavior than other targets, like field-reversed configurations, which may lead to significant flux decay when translating a Taylor State through a series of coils [77].…”

Section: Exploratory Concepts Lawrence Berkeley National Laboratomentioning

confidence: 99%

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Retrospective of the ARPA-E ALPHA Fusion Program

et al. 2019

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This paper provides a retrospective of the ALPHA (Accelerating Low-cost Plasma Heating and Assembly) fusion program of the Advanced Research Projects Agency-Energy (ARPA-E) of the U.S. Department of Energy. ALPHA's objective was to catalyze research and development efforts to enable substantially lower-cost pathways to economical fusion power. To do this in a targeted, focused program, ALPHA focused on advancing the science and technology of pulsed, intermediate-density fusion approaches, including magneto-inertial fusion and Z-pinch variants, that have the potential to scale to commercially viable fusion power plants. The paper includes a discussion of the origins and framing of the ALPHA program, a summary of project status and outcomes, a description of associated technology-transition activities, and thoughts on a potential follow-on ARPA-E fusion program. Introduction:In 2014 the Advanced Research Projects Agency-Energy (ARPA-E) of the U.S. Department of Energy (DOE) launched a new research program on low-cost approaches to fusion-energy development [1]. The "Accelerating Low-Cost Plasma Heating and Assembly" (ALPHA) program set out to enable more rapid progress towards fusion energy by establishing a wider range of technological options that could be pursued with smaller, lower-cost experiments, short development and construction times, and high experimental throughput. Mainstream fusion research generally refers to magnetically or inertially confined fusion, both of which require expensive facilities for reasons briefly described below and explored in more detail in several books[2] [3]. ALPHA focused on magneto-inertial fusion (MIF), a class of pulsed fusion approaches with fuel densities in between those of magnetic and inertial fusion[4], [5] [6]. This paper presents a brief background on the origins of the ALPHA program, the results achieved by ALPHA-funded teams, and a look ahead to potential next steps for low-cost fusion development. OriginsARPA-E's mission is to develop transformational new energy technologies [7]. While DOE has pursued fusion energy as a potentially transformational opportunity for decades, ARPA-E had not supported any work in fusion prior to the ALPHA program. This was in part due to a perception that fusion was inherently the realm of "big science" and that ARPA-E, which runs relatively small, targeted, short-term programs across a wide spectrum of energy technologies-did not have a role to play in that development. In launching ALPHA, ARPA-E sought to change this dynamic and bring new players into the field -both in terms of the kinds of teams doing fusion development (e.g., smaller groups and private startups), and in terms of the sources of funding (e.g., private investors). The ALPHA program

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Section: Exploratory Concepts Lawrence Berkeley National Laboratomentioning

confidence: 99%

Section: Exploratory Concepts Lawrence Berkeley National Laboratomentioning

confidence: 99%

Retrospective of the ARPA-E ALPHA Fusion Program

et al. 2019

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“…Over the past two decades, the Swarthmore Spheromak Experiment (SSX) has been used in many different configurations for the study of several interesting phenomena, such as magnetic reconnection [13] and self-organization [11,12], MHD turbulence [8], and magnetothermodynamics [14,15]. In the present configuration, the SSX device features a ∼ = 1.5 m-long high-vacuum chamber in which we generate n e ≥ 10 15 cm −3 , T i ≥ 20 eV, B ≤ 0.5 T hydrogen plasmas (See Figure 1).…”

Section: Ssx Devicementioning

confidence: 99%

Temperature and Lifetime Measurements in the SSX Wind Tunnel

Kaur

Gelber

Light

et al. 2018

Plasma

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We describe ion and electron temperature measurements in the Swarthmore Spheromak Experiment (SSX) MHD wind tunnel with the goal of understanding limitations on the lifetime of our Taylor-state plasma. A simple model based on the equilibrium eigenvalue and Spitzer resistivity predicted the lifetime satisfactorily during the first phase of the plasma evolution. We measured an average T e along a chord by taking the ratio of the C I I I 97.7 nm to C I V 155 nm line intensities using a vacuum ultraviolet (VUV) monochromator. We also recorded local measurements of T e and n e using a double Langmuir probe in order to inform our interpretation of the VUV data. Our results indicated that the plasma decayed inductively during a large part of the evolution. Ion Doppler spectroscopy measurements suggested that ions cooled more slowly than would be expected from thermal equilibration with the electrons, which maintained a constant temperature throughout the lifetime of the plasma.

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“…In experiments using relaxed Taylor states [3][4][5][6], we accelerated and compressed magnetized plasmas while measuring local proton temperature T i , plasma density n e , and magnetic field B. A particular equation of state (EOS) was identified in these experiments [7,8].…”

Section: Introductionmentioning

confidence: 99%

Magnetothermodynamics in SSX: Measuring the Equations of State of a Compressible Magnetized Plasma

Brown

Kaur

2019

Fusion Science and Technology

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Magnetothermodynamics (MTD) is the study of compression and expansion of magnetized plasma with an eye towards identifying equations of state for magneto-inertial fusion experiments.We present recent results from SSX experiments on the thermodynamics of compressed magnetized plasmas. In these experiments, we generate twisted flux ropes of magnetized, relaxed plasma accelerated from one end of a 1.5 m long copper flux conserver, and observe their compression in a closed conducting boundary installed at the other end. Plasma parameters are measured during compression. The instances of ion heating during compression are identified by constructing a PV diagram using measured density, temperature, and volume of the magnetized plasma.The theoretically predicted MHD and double adiabatic (CGL) equations of state are compared to experimental measurements to estimate the adiabatic nature of the compressed plasma. Since our magnetized plasmas relax to an equilibrium described by magnetohydrodynamics, one might expect their thermodynamics to be governed by the corresponding equation of state. However, we find that the magnetohydrodynamic equation of state is not supported by our data. Our results are more consistent with the parallel CGL equation of state suggesting that these weakly collisional plasmas have most of their proton energy in the direction parallel to the magnetic field.

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Measuring the equations of state in a relaxed magnetohydrodynamic plasma

Abstract: Measuring the equations of state in a relaxed magnetohydrodynamic plasma." Physical Review 97.1, 011202(R).

Cited by 11 publications

References 22 publications

Retrospective of the ARPA-E ALPHA Fusion Program

Retrospective of the ARPA-E ALPHA Fusion Program

Temperature and Lifetime Measurements in the SSX Wind Tunnel

Magnetothermodynamics in SSX: Measuring the Equations of State of a Compressible Magnetized Plasma

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