5k10.90 CAN SMASHER

PURPOSE: To blast a tin can into two pieces using electromagnetism.

DESCRIPTION: A large, 240 uF capacitor is charged to 4000 volts and discharged by pulling a string tied to a piece of teflon.  The energy of the cap is discharged through a two-turn coil into which an aluminum soft drink can has been positioned.

This device can be explained in two distinct ways:

(1) The rapidly rising current creates a rapidly rising magnetic field along the axis of the coil, which in turn induces an electric field going in circles inside the coil. The induced electric field causes an electron current in the can which experiences a vxB force in the magnetic field of the coil, causing the can to break into two pieces which are blown to the opposite sides of the lecture hall.

(2) The plasma "theta pinch" phenomenon occurs when the capacitor is discharged. This effect causes radiation pressure on the can which breaks it in two and blasts apart the two halves.

In the photo below, the can on the left is the result of 3 kV of charge in the capacitor.   The can on the right is the result of 4 kV of charge in the capacitor.

This device is DANGEROUS. You must obtain permission from a Lecture-Demonstration staff member
before attempting to operate it by yourself.

EQUIPMENT: Electromagnetic can crusher.

References:
A. W. Desilva, Magnetically Imploded Soft Drink Can, AJP 62(1), 41-45, (1994).
Ronald J. Allen, A Demonstration of the Magnetic Mirror Effect, AJP 30, 867-869 (1962).
James C. Thompson, Magnetic Mirror Effect, AJP 31, 397-398 (1963). 

The capacitor is manufactured by:

JZ 3/20/2000