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InertialElectrostatic Confinement (IEC) for Space Propulsion



IEC is a simple type of fusion reactor developed in the 60's by Farnsworth. Nowadays this reactor is also beeing tested as a in-space propulsion system due to its high Isp.


The Farnsworth-Hirsch fusor, uses Inertial Electrostatic Confinement to fuse atoms together, thats why the name (IEC). Although not so practical to generate Energy, this reactor serves as a viable source of neutrons.


The system works in several steps.


1) Ionization of neutral gas.

2) Townsend Avalanche.

3) Glow discharge.

4) Ions are driven by electric field to the center of the IEC.

a) Travel back and forth through the inner spherical grid

b) Lose kinetic energy by non elastic colisions to other ions.

5) Drawing electrons to the center to neutralise the potential difference of the virtual anode.


It was chosen as a plasma thruster due to its high energy density.


Operation modes:


1) Spot Mode: Small plasmaconfinament inside the cathode grid.

2) Star Mode: Star like plasma inside the whole reactor.

3) Tight-Jet Mode: Tight Plasma jet beeing shoot out of the Reactor.

4) Spray-Jet Mode: Spray like Plasma jet shoot out of the Reactor.


Losses of the process can be design dependent or design independent.

Design dependent:

1) Ion-grid collision.

2) Electron-grid collision

3) Ionization.


Design Independent:

1) Bremsstrahlung.

2) Exitation.

3) Ion-Neutral gas colision.





Image of a IEC Fusor

Different concepts and Potential Well