Collisional Effects on Electron Trajectories in Crossed-Field Devices

Technical Report · Mon Aug 01 04:00:00 EDT 2022

DOI:https://doi.org/10.2172/1884908· OSTI ID:1884908

Komrska, Allison M. ^[1]; Breen, Lorin I. ^[1]; Loveless, Amanda M. ^[1]; Cartwright, Keith L. ^[2]; Garner, Allen L. ^[3]

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1. Purdue Univ., West Lafayette, IN (United States)
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
3. Purdue Univ., West Lafayette, IN (United States); Elmore Family School of Electrical and Computer Engineering, West Lafayette, IN (United States)

Crossed-field diodes (CFDs) are used in multiple high-power applications and are characterized by an applied magnetic field orthogonal to the electric field, induced by the applied voltage across the anode-cathode gap. In vacuum, the Hull cutoff magnetic field (HCMF) represents the maximum applied magnetic field for which an electron from the cathode can reach the anode. This study investigates the effects of non-vacuum conditions on electron trajectories by introducing electron mobility, which represents particle collisions. We used numerical solutions of the electron force law and particle-in-cell simulations (XPDP1) to assess electron motion for various electron mobilities. For magnetic fields above the HCMF in vacuum, reducing the electron mobility increases the time for an electron emitted from the cathode to reach the anode. Reducing mobility below 22 C s/kg eliminates the HCMF for any magnetic field, meaning that an emitted electron will always cross the gap. We derived the magnetic field, mobility, and electron transit time corresponding to this condition by solving for the condition when the electron velocity in the direction across the anode-cathode gap going to zero at the anode. A parametric study of these conditions using theory and XPDP1 is performed under different gap distances, voltages, and magnetic fields.

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• DOE Contract Number: NA0003525
• OSTI ID: 1884908
• Report Number(s): SAND2022-11238R; 709279
• Country of Publication: United States
• Language: English

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