On the feasibility of a negative polarity electric sail

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.

Download Full-text

Increased electric sail thrust through removal of trapped shielding electrons by orbit chaotisation due to spacecraft body

Annales Geophysicae ◽

10.5194/angeo-27-3089-2009 ◽

2009 ◽

Vol 27 (8) ◽

pp. 3089-3100 ◽

Cited By ~ 34

Author(s):

P. Janhunen

Keyword(s):

Solar Wind ◽

Three Dimensional ◽

Electron Gun ◽

Solar Wind Stream ◽

Space Propulsion ◽

Positive Potential ◽

Trapped Electrons ◽

Natural Mechanism ◽

Electric Solar Wind Sail ◽

Positively Charged

Abstract. An electric solar wind sail is a recently introduced propellantless space propulsion method whose technical development has also started. 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 order 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. The amount of obtained propulsive thrust depends on how many electrons are trapped by the potential structures of the tethers, because the trapped electrons tend to shield the charged tether and reduce its effect on the solar wind. Here we present physical arguments and test particle calculations indicating that in a realistic three-dimensional electric sail spacecraft there exist a natural mechanism which tends to remove the trapped electrons by chaotising their orbits and causing them to eventually collide with the conducting tethers. We present calculations which indicate that if these mechanisms were able to remove trapped electrons nearly completely, the electric sail performance could be about five times higher than previously estimated, about 500 nN/m, corresponding to 1 N thrust for a baseline construction with 2000 km total tether length.

Download Full-text

Method for vacuum state evaluation based on analysis of dynamics changes of electron field emission current and X-radiation in time

20th International Symposium on Discharges and Electrical Insulation in Vacuum ◽

10.1109/isdeiv.2002.1027349 ◽

2003 ◽

Cited By ~ 4

Author(s):

K. Walczak

Keyword(s):

Field Emission ◽

Vacuum State ◽

Emission Current ◽

Electron Field Emission ◽

State Evaluation ◽

Field Emission Current ◽

Electron Field ◽

Analysis Of Dynamics

Download Full-text

Evaluation of internal pressure of vacuum interrupters based on dynamics changes of electron field emission current and X-radiation

11th International Symposium on High-Voltage Engineering (ISH 99) ◽

10.1049/cp:19990918 ◽

1999 ◽

Author(s):

K. Walczak

Keyword(s):

Internal Pressure ◽

Field Emission ◽

Emission Current ◽

Electron Field Emission ◽

Field Emission Current ◽

Electron Field

Download Full-text

Electric solar wind sail mass budget model

Geoscientific Instrumentation Methods and Data Systems ◽

10.5194/gi-2-85-2013 ◽

2013 ◽

Vol 2 (1) ◽

pp. 85-95 ◽

Cited By ~ 39

Author(s):

P. Janhunen ◽

A. A. Quarta ◽

G. Mengali

Keyword(s):

Solar Wind ◽

Solar System ◽

High Speed ◽

Solar Wind Plasma ◽

Performance Model ◽

Propulsion System ◽

Electron Gun ◽

Design Parameters ◽

Plasma Stream ◽

Electric Solar Wind Sail

Abstract. The electric solar wind sail (E-sail) is a new type of propellantless propulsion system for Solar System transportation, which uses the natural solar wind to produce spacecraft propulsion. The E-sail consists of thin centrifugally stretched tethers that are kept charged by an onboard electron gun and, as such, experience Coulomb drag through the high-speed solar wind plasma stream. This paper discusses a mass breakdown and a performance model for an E-sail spacecraft that hosts a mission-specific payload of prescribed mass. In particular, the model is able to estimate the total spacecraft mass and its propulsive acceleration as a function of various design parameters such as the number of tethers and their length. A number of subsystem masses are calculated assuming existing or near-term E-sail technology. In light of the obtained performance estimates, an E-sail represents a promising propulsion system for a variety of transportation needs in the Solar System.

Download Full-text

Large and Stable Field-Emission Current from Heavily Si-Doped AlN Grown by MOVPE

MRS Proceedings ◽

10.1557/proc-621-r5.12.1 ◽

2000 ◽

Vol 621 ◽

Cited By ~ 1

Author(s):

Makoto Kasu ◽

Naoki Kobayashi

Keyword(s):

Electric Field ◽

Field Emission ◽

Light Emission ◽

Electron Field Emission ◽

Maximum Current Density ◽

Field Emission Current ◽

Maximum Current ◽

Electron Field ◽

Si Doped ◽

Stable Field

ABSTRACTWe investigated electron field emission (FE) from heavily Si-doped AlN grown by metalorganic vapor phase epitaxy. We found that, as the Si-dopant density increases, the threshold electric field decreases, which indicates that electrons are supplied to the surface effectively as a result of Si doping. We show that heavily Si-doped AlN has a maximum FE current of 347 μA (the maximum current density of 11 mA/cm2), stable FE current (fluctuation: 3%), and a threshold electric field of 34 V/μm. We observed visible light emission (luminance: about 1200 cd/m2) from phosphors excited by the field-emitted electrons.

Download Full-text