Electron field emission from broad-area electrodes

Noer, R.

doi:10.1007/bf00617778

Cited by 99 publications

(49 citation statements)

References 92 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Electron emission from sharp, well-cleaned tips follows closely to the Fowler-Nordheim field emission law and its later modifications taking into account finite temperature and other refinements (Alpert et al, 1964;Noer, 1982;Halbritter, 1983) and takes place typically at 1-2 GV/m surface field. (Since the dependence of the current density on the electric field E is proportional to E 2 exp(−1/E), the emission increases rapidly from insignificant to large values.)…”

Section: Electron Field Emission Currentmentioning

confidence: 72%

“…(Since the dependence of the current density on the electric field E is proportional to E 2 exp(−1/E), the emission increases rapidly from insignificant to large values.) For broad-area electrodes containing attached dust, local impurities and adsorbed gases, however, significant electron field emission is typically observed already at ∼100 times smaller fields of order 10 MV/m (Noer, 1982;Halbritter, 1983).…”

Section: Electron Field Emission Currentmentioning

confidence: 99%

“…In the laboratory, there are always two electrodes present, anode and cathode. There are experimental indications that the onset and nature of electron field emission at the cathode also depends on the properties of the anode (Noer, 1982). The physical mechanism is possibly that relatively weak but very localised electron beams initially emitted by the cathode knock loose some ions from the anode upon impacting it.…”

Section: Electron Field Emission Currentmentioning

confidence: 99%

See 2 more Smart Citations

On the feasibility of a negative polarity electric sail

Janhunen

2009

Ann. Geophys.

View full text Add to dashboard Cite

Abstract. An electric solar wind sail is a recently introduced propellantless space propulsion method whose technical development has also started. In its original version, the electric sail consists of a set of long, thin, centrifugally stretched and conducting tethers which are charged positively and kept in a high positive potential of 20 kV by an onboard electron gun. The positively charged tethers deflect solar wind protons, thus tapping momentum from the solar wind stream and producing thrust. Here we consider a variant of the idea with negatively charged tethers. The negative polarity electric sail seems to be more complex to implement than the positive polarity variant since it needs an ion gun instead of an electron gun as well as a more complex tether structure to keep the electron field emission current in check with the tether surface. However, since this first study of the negative polarity electric sail does not reveal any fundamental issues, more detailed studies would be warranted.

show abstract

Section: Electron Field Emission Currentmentioning

confidence: 72%

Section: Electron Field Emission Currentmentioning

confidence: 99%

Section: Electron Field Emission Currentmentioning

confidence: 99%

See 1 more Smart Citation

On the feasibility of a negative polarity electric sail

Janhunen

2009

Ann. Geophys.

View full text Add to dashboard Cite

show abstract

“…Therefore, the local electric field is replaced with PPmV/d, where V is the voltage across the electrodes, d is the electrode gap distance, P is the field enhancement factor, and P^ 's the macroscopic field enhancement factor. The field enhancement factor, p, is a suindard parameter used in vacuum arc applicaiions [23,24] to account for the enhancement of the electric field at the surface of the cathode due to microscopic surface roughness. The macroscopic field enhancement factor, Pn,, accounts for the deviation of the electric field near the cathode tip from the mean field, V/d, due to the cathode and anode geometry.…”

Section: The Determination Of Ihe Mechanism Responsible For Initialmentioning

confidence: 99%

An investigation of the breakdown voltage characteristics of a 30 kWclass ammonia arcjet

Tilley

Bromaghim

McFall

et al. 1993

29th Joint Propulsion Conference and Exhibit

View full text Add to dashboard Cite

Public reporting burden for this collection of information is estimated to average 1 tiour per response, including ttie time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of infomnatlon, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of infomiation if it does not display a currently valid 0MB contr-oi number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) Sep 1993 REPORT TYPE Technical Paper PL-TP-93-3029Approved for Public Release Distribution Unlimited The primary objective of this work was to identify methods to reduce the mean dynamic breakdown voltage (MDBV) of the ammonia propellant in the ESEX 26 kW arcjet. The approach to this objective was to establish a test matrix to investigate the influence of mass flow rate, electrode gap distance, cathode tip shape, and voltage ramp rate on the MDBV. Only the mass flow rale and voltage ramp rale were observed to significantly affect the MDBV; the MDBV was observed to rise as either of ihese parameters were increased. These test results provided the basis for the start circuit redesign for the ESEX flight experiment, and also represent an initial data base of breakdown characteristics in high power ammonia arcjeis. The second objective of this work was to identify the mechanisms associated with propellant breakdown in an arcjet. Progress towards this objective includes the following. A framework for investigating breakdown mechanisms in an arcjet was established which provides explanations for the strong dependence of the MDBV on the voltage ramp rale, the mass flow rate, and other parameters. A combination of a model, the calculation of electric field contours inside of the arcjet, and SEM photographs of a cathode tip indicate that the projection model for enhance field emission cannot alone account for the mean dynamic breakdown voltages observed in ihe high power arcjet. This result suggests that dielectric surface layers on the cathode tip are responsible for the enhanced field emission required to explain the observed MDBVs. SUPPLEMENTARY NOTES I. InU"oductionA reliable ignition method is essential for ihe space qualification of an arcjet propulsion system. Arcjeis are most commonly ignited by applying a high voltage pulse across the electrodes to breakdown the propellant. Following breakdown, the arcjet rapidly (on the order of lOO's of microseconds) transitions into a steady state high power arc. This study will focus on the initial phase of arcjet ignition: propellant breakdown. In ...

show abstract

“…In situ cleaning by plasma glow discharge was also tested to see whether an improvement was noticeable in the mitigation of the dark current. This technique of gas conditioning to lower the field enhancement factor β has already been reported [14,15,16] and used successfully in accelerators to process niobium accelerating cavities, see description in [12], as well as for curing other issues [17].…”

Section: Introductionmentioning

confidence: 99%

Field emission dark current of technical metallic electrodes

Pimpec

Ganter

Betemps

2007

Nuclear Instruments and Methods in Physics Research Section A:

View full text Add to dashboard Cite

In the framework of the Low Emittance Gun (LEG) project, high gradient acceleration of a low emittance electron beam will be necessary. In order to achieve this acceleration, a -500 kV, 250 ns FWHM, pulse will be applied between two electrodes. Those electrodes should sustain the pulsed field without arcing, must not outgas and must not emit electrons. Ion back bombardment, and dark current will be damaging to the electron source as well as for the low emittance beam. Electrodes of commercially available OFE copper, aluminium, stainless steel, titanium and molybdenum were tested, following different procedures including plasma glow discharge cleaning.

show abstract

Electron field emission from broad-area electrodes

Cited by 99 publications

References 92 publications

On the feasibility of a negative polarity electric sail

On the feasibility of a negative polarity electric sail

An investigation of the breakdown voltage characteristics of a 30 kWclass ammonia arcjet

Field emission dark current of technical metallic electrodes

Contact Info

Product

Resources

About