A microwave energy source that generates a microwave energy is disclosed. The microwave energy source has an on-state and an off-state. A control circuit is coupled to the microwave energy source and includes an output to generate a control signal that adjusts a pulse frequency of the microwave energy. A voltage generator applies a non-zero voltage to the microwave energy source during the off-state. A frequency and a duty cycle of the non-zero voltage is based on a frequency and a duty cycle of the control signal. A waveguide is coupled to the microwave energy source. The waveguide has a supply gas inlet that receives a supply gas, a reaction zone that generates a plasma, a process inlet that injects a raw material into the reaction zone, and an outlet that outputs a powder based on a mixture of the supply gas and the raw material within the plasma.

A microwave energy source that generates a microwave energy is disclosed. The microwave energy source has an on-state and an off-state. A control circuit is coupled to the microwave energy source and includes an output to generate a control signal that adjusts a pulse frequency of the microwave energy. A voltage generator applies a non-zero voltage to the microwave energy source during the off-state. A frequency and a duty cycle of the non-zero voltage is based on a frequency and a duty cycle of the control signal. A waveguide is coupled to the microwave energy source. The waveguide has a supply gas inlet that receives a supply gas, a reaction zone that generates a plasma, a process inlet that injects a raw material into the reaction zone, and an outlet that outputs a powder based on a mixture of the supply gas and the raw material within the plasma.

Provided is a linearly polarized ultra-short terahertz wave generating device which has a parabolic barrel mirror installed at one side of a multiple thin film, to generate an ultra-short terahertz wave having single linear-polarized light and uniformly formed output distribution.

To suppress both influence of electron emission from a cathode side surface and consumption of energy to be supplied to a heater, while being provided with a grid, an electron gun of the present invention includes: a cathode capable of emitting electrons by heating; a grid capable of controlling the electron emission; and a cathode shield which is an conductor including a material portion located in the vicinity of a side surface of the cathode and facing at least a portion of the side surface via a gap or a heat insulating material, and not being made in direct physical coupling nor in direct physical contact with the cathode.

Provided is a linearly polarized ultra-short terahertz wave generating device which has a parabolic barrel mirror installed at one side of a multiple thin film, to generate an ultra-short terahertz wave having single linear-polarized light and uniformly formed output distribution.

To suppress both influence of electron emission from a cathode side surface and consumption of energy to be supplied to a heater, while being provided with a grid, an electron gun of the present invention includes: a cathode capable of emitting electrons by heating; a grid capable of controlling the electron emission; and a cathode shield which is an conductor including a material portion located in the vicinity of a side surface of the cathode and facing at least a portion of the side surface via a gap or a heat insulating material, and not being made in direct physical coupling nor in direct physical contact with the cathode.

A main power supply 51 supplies power to a main voltage circuit 5 applying a voltage to an electron gun unit 2a and a collector unit 26, a body power supply 31 supplies power to a body voltage circuit 3 applying a voltage to a body unit 25 and the collector unit 26, and a body power supply stabilization circuit 33 maintains an input/output voltage varying between an electron gun side supply line 51b of the main power supply 51 in the main voltage circuit 5 and a body side supply line 31b of the body power supply 31 in the body voltage circuit 3 at a predetermined output voltage.