Recommended Practice for Use of Inductive Magnetic Field Probes in Electric Propulsion Testing

Polzin, Kurt A.; Hill, Carrie; Turchi, P. J.; Burton, Rodney L.; Messer, Sarah; Lovberg, R. H.; Hallock, Ashley K.

doi:10.2514/1.b35406

Cited by 13 publications

(8 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This operating point corresponded to the highest total efficiencies from a recent performance study [23]. The pre-pulse neutral density is estimated to be in the n ≈ 1 × 10 19 range, and at its peak plasma density has been measured at n e ≈ 1× 10 19 1 m −3 with electron temperature peaking at T e ≈ 9 eV [13].…”

Section: Operating Conditionsmentioning

confidence: 82%

“…The magnetic field measurements presented in this work were acquired using a two-axis Bdot probe constructed according to electric propulsion community best practices [19]. This probe consists of two orthogonally-oriented 1.25 cm diameter by 0.64 cm long fiberglass bobbins, around which 24 AWG enameled copper wire is wound.…”

Section: Inductive Probesmentioning

confidence: 99%

“…where we have made the assumption that the induced plasma current runs only in the azimuthal direction. We assume in equation ( 7) that displacement currents are negligible in our device per [19]. This stems from the fact that displacement fluctuations are only expected at frequencies greater than the plasma frequency.…”

Section: Current and Forcementioning

confidence: 99%

See 2 more Smart Citations

Inductive probe measurements in a rotating magnetic field thruster

Sercel,

Gill,

Jorns

2023

Plasma Sources Sci. Technol.

View full text Add to dashboard Cite

The induced magnetic field during acceleration in a pulsed rotating magnetic field (RMF) thruster is experimentally investigated. A two-axis Bdot probe is employed to characterize the time-resolved evolution of the fields in a 5 kW-class test article. This device is operated at an average power of 4 kW with an RMF frequency of 415 kHz, pulse widths of 125 µs, and a repetition rate of 155 Hz. Plasma currents induced in the thruster are shown to be 2500 A and to have sufficient magnitude to form a Field-Reversed Configuration (FRC) plasmoid. The Lorentz force resulting from the induced magnetic field contributes ∼25% of measured thrust at this operating condition. Of this Lorentz thrust, ∼58% is due to plasma current interaction with the steady applied bias field, while the remainder is caused by interaction with secondary induced currents in nearby structural elements. This structure force is predicted to scale quadratically with plasma current magnitude. These results are discussed in the context of the historically low performance of these devices and strategies for improving their operation are presented.

show abstract

Section: Operating Conditionsmentioning

confidence: 82%

Section: Inductive Probesmentioning

confidence: 99%

See 1 more Smart Citation

Inductive probe measurements in a rotating magnetic field thruster

Sercel,

Gill,

Jorns

2023

Plasma Sources Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…The first probe was located 0.5 cm from the drive coil face and 0.81 cm from the coil mid-plane. To calibrate output of the probes, a sensitivity curve was found for the range 100 kHz-500 kHz by using a pulsed Helmholtz coil in accordance with the procedure given by Polzin et al [21]. Integration of the Ḃr signals to obtain B r was achieved numerically using the same procedure for integrating data from the plasma Rogowski coil.…”

Section: Magnetic Field Measurementsmentioning

confidence: 99%

Current sheet evolution in a planar inductive pulsed plasma thruster

Promislow,

Little

2024

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

The evolution of the current sheet is fundamental to the understanding and operation of planar inductive pulsed plasma thrusters. Methods for experimentally determining the time-varying mutual inductance and plasma resistance associated with the current sheet are presented. From these, time-histories of the resistive heating in and electromagnetic acceleration of the sheet are found. Analysis of experimental data obtained from a compact, low discharge energy inductive pulsed plasma thruster shows that current sheet evolution is well described by three phases: ionization, formation, and acceleration. Evidence is provided for the plasma current and resistive heating becoming localized near the upstream edge of the current sheet as the sheet forms. The influence of initial propellant density and pre-ionization on the characteristics of the sheet are examined. Both higher propellant densities and increased pre-ionization are found to produce current sheets which exhibit greater magnetic impermeability. Higher densities cause the sheet to form closer to the coil face, improving coupling, while stronger pre-ionization leads to more rapid resistive heating, causing the sheet to form earlier in time.

show abstract

“…Inductive magnetic field probes, also called Ḃ probes, are routinely used in electric propulsion testing to measure unsteady magnetic field produced by time-varying currents [14,15,[43][44][45][46], and in laboratory magnetic confined plasma to detect magnetic field perturbation and MHD instabilities [10,47]. Operationally, these types of probes self-generate an output voltage when immersed in a time-changing magnetic field, proportional to dB/dt.…”

Section: Diagnosticsmentioning

confidence: 99%

Resistive MHD modes in hollow cathodes external plasma

Becatti¹,

Burgalassi²,

Paganucci³

et al. 2022

Plasma Sources Sci. Technol.

View full text Add to dashboard Cite

A significant number of plasma instabilities occur in the region just outside of hollow cathodes, depending on the injected gas flow, the current level and the application of an external magnetic field. In particular, the presence of an axial magnetic field induces a helical mode, affecting all the plasma parameters and the total current transported by the plasma. To explore the onset and behavior of this helical mode, the fluctuations in the plasma parameters in the current-carrying plume outside of a hollow cathode discharge have been investigated. The hollow cathode was operated at a current of 25 A, and at variable levels of propellant flow rate and applied magnetic fields. Electromagnetic probes were used to measure the electromagnetic fluctuations, and correlation analysis between each of the probe signals provided spatial-temporal characterization of the generated waves. Time-averaged plasma parameters, such as plasma potential and ion energy distribution function, were also collected in the near-cathode plume region by means of scanning emissive probe and retarding potential analyzer. The results show that the helical mode exists in the cathode plume at sufficiently high applied magnetic field, and is characterized by the presence of a finite electromagnetic component in the axial direction, detectable at discharge currents $\geq$ 25 A. A theoretical analysis of this mode reveals that one possible explanation is consistent with the hypotheses of resistive magnetohydrodynamics, which predicts the presence of helical modes in the forms of resistive kink. The analysis has been carried out by linear perturbation of the resistive MHD equations, from which it is possible to obtain the dispersion relation of the mode and find the $k-\omega$ unstable branch associated with the instability. These findings provided the basis for more detailed investigation of resistive MHD modes and their effect in the plume of hollow cathodes developed for electric propulsion application.

show abstract

Recommended Practice for Use of Inductive Magnetic Field Probes in Electric Propulsion Testing

Cited by 13 publications

References 9 publications

Inductive probe measurements in a rotating magnetic field thruster

Inductive probe measurements in a rotating magnetic field thruster

Current sheet evolution in a planar inductive pulsed plasma thruster

Resistive MHD modes in hollow cathodes external plasma

Contact Info

Product

Resources

About