| Saint Elmo's Fire |
| Ingredients: 1 Charcoal Briquet 1 Sq. Ft. Aluminum foil 5 Coins 1 Discarded oven-safe bowl. 1 Unwanted microwave oven |
| Procedure: Wad the foil to form a bed for the charcoal. Place it in an oven-safe bowl. Drop the briquet on top. Sprinkle with coins. Cook the assembly, using maximum power, for five minutes. Watch carefully . . . . |
| Waveguide Arc Fault Warning: Saint Elmo's Fire will eventually enter the port supplying your microwave power. Saint Elmo's fire naturally encroaches upon an RF power source. Once it's in the waveguide, the superheated plasma spells doom. Don't blow your source. Your mission, should you choose to accept, is to open the door whenever you sense there's zapping you cant see. It will sound like: BVVvvvfffff.... Once extinguished, you are free to close the door, and retstart the Saint Elmo's Fire. |
| Caution: Arc-byproducts are nasty. Hot residue, fumes, and ultra-violet radiation all present hazzards. Consult your health physicist for details (or ask your mom to supervise). |
| Do this outdoors. Stand upwind. |
| Process Description: The briquet is a microwave susceptor. It comes to glow dull red. Flammable gasses are expelled. Arcing occurs between the metal objects. This arcing requires non-contact close spacing. Arcs can ignite flammable gasses leaving the briquet. Flames absorb microwave power. The flame becomes self-sustaining, without need for further flammable gas input. We call this "ionization," or Saint Elmo's Fire. This can waft pleasantly around a microwave-oven interior, until it flickers out, or until it gets into the waveguide. We jerk the door open to end each event. Caution: We always avoid breathing metal vapor. |
| My briquettes may have been wet or moist. They were outside when I found them. Spontaneous combustion can occur when wet charcoal decomposes in a confined space. For safety, wet charcoal should be dried outdoors, in a BBQ, a safe distance from other flammable materials. |
| VSWR related problems . . . . Microwave power can hit a dead-end and reflect back into its source. This is happens when we run a microwave oven while it is empty. Forward and reflected waves meet in passing, tending for a given region, to either cancel or add. A pattern of "hotspots" (or antinodes) forms, wherever waves are additive. This pattern of antinodes appears motionless. We call these motionless patterns standing waves. They ring electrically like a bell rings physically. Designers usually detest them. As power pours in, the ringing gets bigger. Eventually, standing-wave voltage gets so high break-down occurs (it arcs somewhere). An over-temperature cutout switch on the waveguide, near the microwave source, interrupts resulting waveguide arcs. Internals of the Magnetron-tube (microwave source) are also subjected to these voltage extreems. It's like a house of mirrors, the waves bounce back and fourth with increasing intensity. Tubes may arc internally with excessive standing-wave voltage buildup. Tube-arcs, if sustained, will eventually blow the power fuse. If your microwave appears completely dead, check the fuse. To do so, unplug the unit. Remove the cover. Find the fuse, and if it's bad, replace it. |
| When the ember at the center of the charcoal briquete gets small, turn the microwave oven off. |
| VSWR stands for (Voltage : Standing Wave) Ratio. |
| A VSWR of 1:1 would exist if we presented forward power and found none reflected back. In practice, we never quite achieve such a "perfect match." Perfect matching would require identical source impedance, transmission-line impedance, and load impedance. A perfect match could also exist if perfect transformers were used to couple dissimilar impedances characteristic-to source, line, and load. Commercial broadcast antenna matching appears feasible to a VSWR of 1:1.05. |
|
| Caution: We break the law when we damage US currency and put it back into circulation. Pottery Barn Rule: You break it, you bought it. |