Magnetron Weedkiller

thedatastream, Fri May 25 2007, 07:55PM

Just watching Chelsea Flower Show on the BBC and a thought occurred - could you use an old microwave magnetron and MOT to destroy weeds / slugs / snails / garden pests?

Requirements would be safety (long pole, pointintg away, limiting power output) and effectivness.

Any comments? Anyone tried this before? Something like this would be interesting (have to pay to get the paper :( Link2 )

Any safety concerns with reflected microwave energy?

What sort of waveguide should one use for focusing the microwave energy?

Is the controlling of power as simple as controlling the mains supply voltage to the magnetron (like SCR controlled power supply) or would a PWM of the magnetron short pulses of high power) be better?

Thanks
James
Re: Magnetron Weedkiller
Adrian, Sat May 26 2007, 10:35AM

Reflected microwave energy could damage your or other peoples eyes. Reflections may cause minor heating in surfaces the microwaves touch but I doubt it would be detectable at larger distances (1m+).

I suspect whatever device their prototype uses had a enclosure that sits over the weeds and creates a seal as to prevent escaping radiation. I also think this is aimed at large-area weed control (several square feet at a time) as I imagine its pointlessly impractical to kill a few here-and-there weeds found in a typical decently maintained garden.

IIRC, microwaves reflect off the ground.

Heat may not effect weeds too much. Small pests (ants etc) will most likely remain unharmed (this was discussed years ago at the hv community...).

You might be able to make a snail boil or something, they're probably 80+% water.