Adiabatic Compression of a Compact Torus

Woodruff, S.; Stuber, James; Bowman, Craig T.; Sieck, P.E.; Melnik, Paul; Romero-Talamás, C.A.; O'Bryan, J.B.; Miller, Robert L.

doi:10.1080/15361055.2017.1350488

Cited by 2 publications

(1 citation statement)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We are considering two approaches for sustaining and heating a spheromak plasma to fusion temperatures: multi-pulse coaxial helicity injection (CHI) in this paper and magnetic compression in Ref. 4. For both approaches, the initial spheromak plasma is formed by CHI.…”

Section: Introductionmentioning

confidence: 99%

Simulation of multi-pulse coaxial helicity injection in the Sustained Spheromak Physics Experiment

2018

Self Cite

View full text Add to dashboard Cite

Nonlinear, numerical computation with the NIMROD code is used to explore magnetic selforganization during multi-pulse coaxial helicity injection in the Sustained Spheromak Physics eXperiment. We describe multiple distinct phases of spheromak evolution, starting from vacuum magnetic fields and the formation of the initial magnetic flux bubble through multiple refluxing pulses and the eventual onset of the column mode instability. Experimental and computational magnetic diagnostics agree on the onset of the column mode instability, which first occurs during the second refluxing pulse of the simulated discharge. Our computations also reproduce the injector voltage traces, despite only specifying the injector current and not explicitly modeling the external capacitor bank circuit. The computations demonstrate that global magnetic evolution is fairly robust to different transport models and, therefore, that a single fluid-temperature model is sufficient for a broader, qualitative assessment of spheromak performance. Although discharges with similar traces of normalized injector current produce similar global spheromak evolution, details of the current distribution during the column mode instability impact the relative degree of poloidal flux amplification and magnetic helicity content.

show abstract

Section: Introductionmentioning

confidence: 99%

Simulation of multi-pulse coaxial helicity injection in the Sustained Spheromak Physics Experiment

2018

Self Cite

View full text Add to dashboard Cite

show abstract

Numerical study and optimization of the formation and sustainment of a coaxial helicity injection spheromak

2018

View full text Add to dashboard Cite

Nonlinear, numerical computation with the NIMROD code is used to explore magnetic self-organization during the formation, sustainment, and relaxation of a spheromak with coaxial helicity injection. The formation process is largely insensitive to the local current distribution in the annular current column and details of the injector current trace, instead depending on the peak injected current (specifically λinj/λeig) and the bias flux Ψbias. The injected flux Φinj needed to trigger the column mode instability, the resulting local poloidal flux amplification AΨ, the amount of injected energy retained in the plasma as magnetic energy ηM, and the magnetic helicity per unit of injected energy ηK all scale with λinj/λeig. Both Φinj and ηK scale with the bias flux Ψbias, and ηM and ηK scale inversely with the pre-fill density. Sustained relaxation occurs when the injector current is maintained between two threshold values, 0.8 < λinj/λeig < 1 for the geometry studied. Overall, our results suggest that the performance of the spheromak configuration is very robust and therefore allows for flexibility in the design and operation of a Proof-of-Principle spheromak concept.

show abstract

Adiabatic Compression of a Compact Torus

Abstract: County (UMBC) ScholarWorks@UMBC digital repository on the Maryland Shared Open Access (MD-SOAR) platform.

Cited by 2 publications

References 13 publications

Simulation of multi-pulse coaxial helicity injection in the Sustained Spheromak Physics Experiment

Simulation of multi-pulse coaxial helicity injection in the Sustained Spheromak Physics Experiment

Numerical study and optimization of the formation and sustainment of a coaxial helicity injection spheromak

Contact Info

Product

Resources

About