Ferromagnetic element with temperature regulation

In a temperature regulating device:

• a ferromagntic element having a permeability well above unity at temperature well below the effective Curie temperature of said element, and
• control means for applying pulses of electric current to said element with each pulse heating said element to tis effective Curie temperature;
• said element cooling between pulses,
• said control means including means for sensing the permeability of said element during each pulse and for terminating such pulse when such permability declines to a given value and for sensing the permeability of said element after the cessation of each pulse and for producing the next pulse only after said element has cooled so that its permeability is above said given value.

Temperature regulating apparatus, for holding the temperature of a heating element substantially constant while such element is subject to varying cooling loads, comprising:

• a heating element of the type that when in use is subject to a varying cooling load,
• said heating element including:
• a ferromagnetic element having a permeability substantially greater than one when its temperature is below its effective Curie temperature and a permeability on the order of one when its temperature is above its effective Curie temperature,
• power delivery means feeding an electric current, through said element, of sufficient amplitude which if maintained continuously and indefinitely, would heat said element far above its effective Curie temperature, so that said element has a Curie transition characterized by a change in permeability of said element, and
• control means including means for supplying power to said element in the form of a series of pulses of current with each pulse rising to said amplitude, said control means comprising means for sensing said permeability during each pulse and at least reducing said electric current to said element to terminate the pulse in response to such pemreability falling to a give value during an increase in temperature in said element,
• said control means restoring said electric current to said element to start the next pulse only when said permeability is above said given value due to cooling of said element;
• whereby a series of pulse is produced, each of which pulses reaches said amplitude, and each of which pulses is of greater duration for larger cooling loads than for smaller cooling loads;
• said pulses holding said element at said substantially constant temperature.

The method of temperature regulation, of a heating element subject to a variable cooling load, comprising:

• providing said element with ferromagnetic material having a permeability considerably greater than one below its effective Curie temperature and a permeability on the order of one above its effective Curie temperature,
• subjecting said element to at least two cooling loads one of which is larger than another one,
• passing an electric current, of sufficient amplitude which if fed through said element for a prolonged period will heat said element well above its effective Curie temperature, through said element to heat said element at least to a temperature high enough so that at least a part of the Curie transition takes place,
• sensing at least part of said Curie transition and reducing the flow of said current through said element when at least part of said Curie transition is sensed, and
• restoring said current through said element to said amplitude,
• said sensing and restoring steps recurring alternately to thus provide a pulsating current that holds said element at about its effective Curie temperature and at all times prevents a rise in the temperature of said element substantially above its effective Curie temperature,
• said pulsating current comprising pulses of greater time duration for the larger cooling load than for the said another one.

Temperature regulating apparatus, for holding the temperature of a heating element substantially constant while such element is subject to varying cooling loads, comprising:

• a heating element of the type that when in use is subject to a varying cooling load,
• said heating element including:
• a ferromagnetic element having a permeability substantially greater than one when its temperature is below its effective Curie temperature and a permeability on the order of one when its temperature is above its effective Curie temperature,
• a radio frequency power supply feeding current, through said element, of sufficient amplitude, that if maintained continuously and indefinitely, would heat said element far above its effective Curie temperature, so that said element has a Curie transition,
• said power supply having an output and also having the parameters of both current and voltage at said output,
• feedback means for holding one of said parameters, when the current is on, substantially constant at said output, and
• control means for sensing changes in the other of said parameters for turning said radio frequency power supply off and on to produce a series of pulses, said control means turning said power supply off when the permeability of said element falls to a given value due to the heating of said element.

The method of temperature regulation, comprising,

• providing a ferromagnetic element having a permeability well above unity at temperatures well below the effective Curie temperature of said element,
• applying pulses of electric current to said element with each pulse heating said element to its effective Curie temperature,
• allowing said element to cool between pulses,
• sensing the permeability of said element during each pulse and terminating such pulse when such permeability declines to a give value, and
• sensing the permeability of said element after the cessation of each pulse and producing the next pulse only after said element has cooled so that its permeability is above said given value.