Heater, apparatus, and associated method

An apparatus, comprising:

• a heating element operable to heat to a temperature in a range of greater than 500° C.;
• a cement matrix encasing the heating element, the cement matrix having a first surface and a second opposing surface;
• a first tube communicating with the first surface of the cement matrix and providing mechanical support thereto, and a second tube communicating with the second surface of the cement matrix;
• and
• during operation, energy supplied to the heating element causes thermal energy to flow into the first tube to a capsule disposed within a region of the first tube, the thermal energy is sufficient to increase the capsule temperature to be in a range of greater than 500° C., and to generate pressure within the capsule to be in a range of greater than 500 MPa as a response to the increase in temperature while the first tube is restrained by the cement matrix such that a volume within the capsule increases in an amount of less than 5 percent.