Speaker
Description
Jensen’s model[1] for General Thermal-Field (GTF) emission enables increased precision for injecting electrons self-consistently into physics simulations where electron emission is important, such as vacuum arcs, transmission lines in pulsed power systems, or vacuum diodes. Due to increased computational expense, however, it is important to understand when simpler models may be reasonably used. Of perhaps greatest potential impact: when can simple, effective, space-charge limited (SCL) models be used? By applying the incredibly simple theoretical technique of nexus theory[2] (only slightly more sophisticated than scaling arguments), one can find parameters “in the ballpark” where GTF or SCL are appropriate. To test nexus theory of the GTF-SCL transition, simple Particle-In-Cell simulations in EMPIRE-PIC[3] will be presented. Details of the GTF and SCL implementations in EMPIRE will be briefly discussed, especially as they pertain to serious local instabilities in GTF which, nevertheless, result in nearly-correct aggregate behavior.
[1] K. L. Jensen, “A reformulated general thermal-field emission equation,” J. Appl. Phys. 126, 065302 (2019).
[2] A. M. Darr, C. R. Darr, and A. L. Garner, “Theoretical assessment of transitions among thermionic, field, and space-charge-limited emission,” Phys. Rev. Research 1, 033137 (2020).
[3] M. T. Bettencourt et al., “EMPIRE-PIC: A performance portable unstructured Particle-in-Cell code,” Communications in Computational Physics 30, SAND-2021-2806J (2021).
Acknowledgements:
This work was supported by the Assured Survivability and Agility with Pulsed Power (ASAP) Mission Campaign sponsored Maxwell Fellowship awarded to Adam M. Darr under the Laboratory Directed Research and Development program at Sandia National Laboratories.
Sandia National Laboratories (SNL) is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia under the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
