dielectric heating , also: capacity current heating

The best understood biological effect of electromagnetic fields is to cause dielectric heating.

This provides for highly efficient, but less penetrative, dielectric heating.

For dielectric heating, the generated power density per volume is given by:

Water, fat, and other substances in the food absorb energy from the microwaves in a process called dielectric heating.

When injury from exposure to microwaves occurs, it usually results from dielectric heating induced in the body.

Industrially they are used in plasma generating equipment, for dielectric heating, and in semiconductor manufacturing.

Dielectric heating involves the heating of electrically insulating materials by dielectric loss.

Changing electric dipole fields, as such, are used commercially as near-fields mainly as a source of dielectric heating.

Dielectric heating must be distinguished from Joule heating of conductive media, which is caused by induced electric currents in the media.

Dielectric heating (diathermy) is used in medicine; the frequencies used typically lie in the ultrasonic, shortwave, and microwave ranges.

To support this A-shape, the plywood armrest, which is curved at a right angle (through high-frequency dielectric heating), is affixed to the upper section.

Metals absorb this energy much more efficiently than tissue through dielectric heating; Richard Smalley has suggested that carbon nanotubes could be used to similar purpose.

Dielectric loss is caused when the insulating material inside the transmission line absorbs energy from the alternating electric field and converts it to heat (see dielectric heating).

Methods of electric heating include resistance heating, electric arc heating, induction heating, and dielectric heating.

A microwave oven passes (non-ionizing) microwave radiation (at a frequency near 2.45 GHz) through food, causing dielectric heating primarily by absorption of the energy in water.

The ADS millimeter wave energy works on a similar principle as a microwave oven, exciting the water and fat molecules in the skin, and instantly heating them via dielectric heating.

Dielectric heating at low frequencies, as a near-field effect, requires a distance from electromagnetic radiator to absorber of less than about 1/6 of a wavelength (λ/2π) of the source frequency.

In agriculture, RF dielectric heating has been widely tested and is increasingly used as a way to kill pests in certain food crops after harvest, such as walnuts still in the shell.

One well-understood effect of microwave radiation is dielectric heating, in which any dielectric material (such as living tissue) is heated by rotations of polar molecules induced by the electromagnetic field.

Nevertheless, the primary heating effect of all types of electromagnetic fields at both radio and microwave frequencies occurs via the dielectric heating effect, as polarized molecules are affected by a rapidly alternating electric field.

If the conductivity of the material is small, or the frequency is high, such that (with ), then dielectric heating is the dominant mechanism of loss of energy from the electromagnetic field into the medium.

Unlike Ohmic heating by electric current passing through the conductive tissue in conventional electrosurgery, diathermy means dielectric heating, produced by rotation of molecular dipoles in high frequency alternating electric field.

Dielectric heating of liquid water is also temperature-dependent: At 0 C, dielectric loss is greatest at a field frequency of about 10 GHz, and for higher water temperatures at higher field frequencies.

Dipole rotation is the mechanism normally referred to as dielectric heating, and is most widely observable in the microwave oven where it operates most efficiently on liquid water, and much less so on fats and sugars.

Shigeru Nakajima, a younger brother of Yoji Ito and a scientist at the Japan Radio Company (JRC), was also investigating magnetrons, primarily for the medical dielectric heating (diathermy) market.