A system for implementing a power source to initiate and sustain a test sample in a plasma state within a plasma torch, comprising: a power amplifier adapted to generate, at an output, a radio-frequency power signal with an adjustable operating frequency, said output of said power amplifier being connected to an input of an impedance match, so as to provide said radio frequency power signal thereto, said power amplifier further being adapted to generate a reference phase signal derived from said radio-frequency power signal; a variable power supply adapted to supply power to said power amplifier; said impedance match adapted to provide said radio-frequency power signal to a plasma coil that has a variable resonance condition and is positionable adjacent to said plasma torch; a phase probe positioned adjacent to said plasma coil adapted to generate a coil phase signal corresponding to said adjustable operating frequency; a phase-locked loop device including a phase detector, wherein said phase detector is adapted to receive and compare said reference phase signal, derived from said output of said power amplifier, to said coil phase signal to determine a phase relationship between said reference signal and said coil phase signal, wherein said phase-locked loop device generates a drive signal to said power amplifier based upon said phase relationship between said reference phase signal and said coil phase signal, and wherein said drive signal controls said adjustable operating frequency so that said phase relationship between said reference phase signal and said coil signal is controlled so as to maintain resonance condition at said plasma coil; and a controller adapted to control said variable power supply to supply a desired power to said power amplifier. a power amplifier adapted to generate, at an output, a radio-frequency power signal with an adjustable operating frequency, said output of said power amplifier being connected to an input of an impedance match, so as to provide said radio frequency power signal thereto, said power amplifier further being adapted to generate a reference phase signal derived from said radio-frequency power signal; a variable power supply adapted to supply power to said power amplifier; said impedance match adapted to provide said radio-frequency power signal to a plasma coil that has a variable resonance condition and is positionable adjacent to said plasma torch; a phase probe positioned adjacent to said plasma coil adapted to generate a coil phase signal corresponding to said adjustable operating frequency; a phase-locked loop device including a phase detector, wherein said phase detector is adapted to receive and compare said reference phase signal, derived from said output of said power amplifier, to said coil phase signal to determine a phase relationship between said reference signal and said coil phase signal, wherein said phase-locked loop device generates a drive signal to said power amplifier based upon said phase relationship between said reference phase signal and said coil phase signal, and wherein said drive signal controls said adjustable operating frequency so that said phase relationship between said reference phase signal and said coil signal is controlled so as to maintain resonance condition at said plasma coil; and a controller adapted to control said variable power supply to supply a desired power to said power amplifier.