Aurora Borealis Experiment - Princeton Plasma Physics Lab .Aurora Borealis Experiment: A Planeterella

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Aurora Borealis Experiment: A Planeterella for

Education and Outreach

The Planeterella is an experiment, invented by Jean

Lilensten of the Labartoire de Planetologie de Grenoble in

France, designed to simulate various space plasma

phenomena, typically aurorae. A Planeterella consists of

two differently sized spheres with magnets inside them,

and a copper electrode. Usually at least one piece is

positively biased while the other is negatively biased.

When the potential between the cathode and anode reach

breakdown voltage, plasma is formed. The plasma

simulates space plasma around planets created by solar

wind. We have made a modified version of the

Planeterella, called the Aurora Borealis Experiment

(ABX), based upon Lilenstens plans.


How it Works



Conclusion and Future Work

Mercer County Community College*, Princeton Plasma Physics Laboratory+ Aurora Borealis Experiment

Courtesy of:

Create a demonstration of space plasma

phenomena that can be used for students at

a variety of levels

Bell jar, aluminum spheres, permanent

magnets, two DC power supplies used to

create necessary conditions

The transfer of charged particles from a

magnetic sphere represent solar wind

Gas is air, plasma is created at breakdown

voltage which depend upon separation of

spheres, pressure, and voltage

Under correct manipulation, magnets inside

the spheres create what appears to be


Electrical Setup

Vacuum Setup

Left: Vacuum pump

Top Right: Exhaust pump

Bottom Right: Pressure

gauge and control

Left: PPPLs Aurora

Borealis Experiment

Left: Entire view of vacuum

setup ready for use

Neodymium permanent magnets with a surface

field of at least 1 Tesla must be used.

Right: Birkelands

original Terella c.1895


Planeterella by J.

Lilensten, the

basis for PPPLs


Left: Aluminum base

plate drafted in Autocad

and cut in PPPL metal


Right: PLA pieces (in

yellow) made from 3D printer along with

aluminum spheres and copper electrode

Left sphere is

negative, right is


Magnets in both

spheres are


No apparent

influence of


Left: Autocad drawing of

aluminum base plate

At 3 inch separations, most discharges occurred

between 450-550V at pressures of 75-95mTorr.

Power supplies used. The left

supply is set to positive while

the right supply is set to


Left sphere is

negative, right is


Vertical magnets in

left sphere and none

in right sphere

No apparent

influence of magnets

Left sphere is

negative, right is


Vertical magnets in

left sphere horizontal

magnets in right

Magnets on right

appear to deform the

plasma around the

left sphere

Arcing to the base plate needs to be fixed

Addition of electromagnets

Move the spheres while under vacuum

Increase strength of permanent magnets

In some configurations the magnets are able

to influence the system

Optimal breakdown conditions: 2.75 inch

separation, 500V, 70mTorr

Michael McNulty*+, Andrew Zwicker*, Andy Carpe*, Josh Bloom*