Generalization of the Langmuir–Blodgett laws for a nonzero potential gradient

Sutherland, Orson; Ankiewicz, Adrian; Boswell, Rod

doi:10.1063/1.1850480

Cited by 9 publications

(9 citation statements)

References 24 publications

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“…A maximum of 30 kV has been obtained in laboratory tests (2005 and 2006) at the European Space Agency development centre (ESTEC) of a dual stage 4 grid (DS4G) ion thruster prototype designed and built at the Space Plasma, Power and Propulsion laboratory at the ANU (Walker et al 2006, Bramanti et al 2009. A generalization of the Langmuir-Blodgett laws used for ion extraction with grids has been recently discussed (Sutherland et al 2005a) which shows the limits of equation ( 9). In summary, ion extraction and acceleration with grids is an effective method and plays a major role in the development of electric propulsion.…”

Section: With Grids (Eg Gridded Ion Thrustersmentioning

confidence: 99%

Plasmas for spacecraft propulsion

Charles

2009

J. Phys. D: Appl. Phys.

331

263

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This review presents the basics of plasma discharges applied to electric spacecraft propulsion. It briefly reports on the mature and flown technologies of gridded ion thrusters and Hall thrusters before exploring the recent yet immature technology of plasma thrusters based on expansion from low pressure high density inductively coupled and wave-excited plasma sources, e.g. the radiofrequency helicon source. Prototype development of plasma engines for future space travel is discussed using the example of the helicon double layer thruster. A summary of highlights in electric propulsion based space missions gives some insight into the challenges of future high power missions in more remote regions of space.

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Section: With Grids (Eg Gridded Ion Thrustersmentioning

confidence: 99%

Plasmas for spacecraft propulsion

Charles

2009

J. Phys. D: Appl. Phys.

331

263

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“…In this section we describe the different SC laws, their applicability to plasma ion source extraction, and how they conflict with the plasma ambipolar flow model [15]. The classical one dimensional CL law answers the question: what is the maximum current density that can be drawn from parallel system of infinitely large emitter and collector pair with a given distance D (emitter at z = 0 and collector at z = D) and voltage V between them, given an infinite supply of charged particles at the emitter?…”

Section: Theorymentioning

confidence: 99%

Critical assessment of the applicability of the Child-Langmuir law to plasma ion source extraction systems

Kosonen

Kalvas

Toivanen

et al. 2023

Plasma Sources Sci. Technol.

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Applicability of the classical one-dimensional and the recently developed multi-dimensional Child-Langmuir laws to plasma ion source extraction systems is studied. Experiments with a filament-driven multicusp ion source using a simplified extraction system, and comprehensive simulations with two different software packages, suggest that ion beams, which are typically assumed to be space charge or Child-Langmuir limited, are actually divergence-limited. In addition, it was observed that the dynamic plasma meniscus and geometric effects of the extraction system have a greater impact on the ion beam behavior than the effects predicted by the multi-dimensional Child-Langmuir law. Nevertheless, it was found that ion beams produced by the ion source exhibit space charge limited behavior, the beam current scaling with the extraction voltage as $I\propto V^{3/2}$, provided that the entire beam is measured and its divergence is kept small and constant for each extraction voltage. This implies that the applicability of the Child-Langmuir law on a specific extraction system cannot be resolved by a straightforward voltage sweep and beam current measurement but instead, the plasma parameters must be adjusted for each extraction voltage. By shifting the focus from the Child-Langmuir limited framework to the divergence-limited framework, a clearer interpretation of the beam current -- voltage characteristics of extraction systems can be achieved. This shift in perspective may also lead to the development of new design paradigms that can further enhance the performance of plasma ion source extraction systems.

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“…[21][22][23][24][25][26][27][28] Tubes in which the trajectories of the electrons are determined by magnetic and electric fields between the cathode and the anode are called magnetrons. 15 If the geometry of the cathode and anode is cylindrically concentric, the structure is called a cylindrical magnetron.…”

Section: Theorymentioning

confidence: 99%

On thermionic emission and the use of vacuum tubes in the advanced physics laboratory

Angiolillo

2009

American Journal of Physics

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Two methods are outlined for measuring the charge-to-mass ratio e / m e of the electron using thermionic emission as exploited in vacuum tube technology. One method employs the notion of the space charge in the vacuum tube diode as described by the Child-Langmuir equation; the other method uses the electron trajectories in vacuum tube pentodes with cylindrical electrodes under conditions of orthogonally related electric and magnetic fields ͑the Hull magnetron method͒. The vacuum diode method gave e / m e = 1.782Ϯ 0.166ϫ 10 +11 C / kg ͑averaged over the vacuum diodes studied͒, and the Hull magnetron method gave e / m e = 1.779Ϯ 0.208ϫ 10 +11 C / kg ͑averaged over both pentodes and the anode voltages studied͒. These methods afford opportunities for students to determine the e / m e ratio without using the Bainbridge tube method and to become familiar with phenomena not normally covered in a typical experimental methods curriculum.

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Generalization of the Langmuir–Blodgett laws for a nonzero potential gradient

Cited by 9 publications

References 24 publications

Plasmas for spacecraft propulsion

Plasmas for spacecraft propulsion

Critical assessment of the applicability of the Child-Langmuir law to plasma ion source extraction systems

On thermionic emission and the use of vacuum tubes in the advanced physics laboratory

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