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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 Lilensten’s plans.

Introduction

How it Works

Construction

Results

Conclusion and Future Work

Mercer County Community College*, Princeton Plasma Physics Laboratory+

Aurora Borealis Experiment

Courtesy of: http://www.globalwarmingclassroom.info/earth_magnetosphere.htm

• 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

aurorae

Electrical Setup

Vacuum Setup

Left: Vacuum pump

Top Right: Exhaust pump

Bottom Right: Pressure

gauge and control

Left: PPPL’s 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: Birkeland’s

original Terella c.1895

Right:

Planeterella by J.

Lilensten, the

basis for PPPL’s

Planeterella

Left: Aluminum base

plate drafted in Autocad

and cut in PPPL metal

shop

Right: PLA pieces (in

yellow) made from 3D printer along with

aluminum spheres and copper electrode

• Left sphere is

negative, right is

positive

• Magnets in both

spheres are

horizontal

• No apparent

influence of

magnets

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

negative

• Left sphere is

negative, right is

positive

• Vertical magnets in

left sphere and none

in right sphere

• No apparent

influence of magnets

• Left sphere is

negative, right is

positive

• 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*