A PORTABLE MICROWAVE SYSTEM FOR WOODWORM DISINFESTATION OF ARTISTIC PAINTED BOARDS

Microwave power can be effectively used for disinfesting wooden object s of woodworms. Disinfestation is achieved by heating woodworms inside wood above their lethal temperature values. A prototype of a portable microwave system suitable for treating small and delicate wooden obje cts is described. The system, working at 2.45 GHz, used a commercial m agnetron, a radiative applicator and a non-contacting thermometer to m onitor the temperature of the painted surface. A flow of air is blown through the applicator to cool the irradiated surface. A treatment ben ch has been set up to heat painted boards in controlled conditions. Th e applicator is placed on the rear side of the board, while the painte d side is monitored by means of an infrared thermometer to maintain it s temperature below safe levels (e.g. 50-55 degrees C). Results concer ning the effect of microwave heating on several specimens infested by woodworms in all metamorphical stages (egg, pupa and larva) are report ed and discussed. Preliminary results about possible detrimental effec ts induced by heating on wooden boards and on painted surfaces are als o reported. An experimental procedure for determining the SAR distribu tion produced by the applicator of the disinfestation system on a wood en board is described. The procedure is based on a thermographic analy sis of the heated object. An analysis of the SAR uncertainty due to th ermal diffusion and to surface radiation and convection losses is carr ied out, showing advantages and limitations of the thermographic metho d.