What characteristic of an ICP source is critical for its function?

The critical characteristic of an inductively coupled plasma (ICP) source that ensures its proper functioning is primarily related to the presence of a high-voltage power supply. In an ICP source, a high-voltage power supply is essential for generating the electromagnetic field required to sustain the plasma. This electric field ionizes the gas, typically argon, allowing the generation of a stable high-temperature plasma that can effectively atomize and excite the sample.

While the composition of the gas used and the temperature of the reaction chamber are important for optimizing the performance of the ICP system, they do not inherently enable the fundamental operation of the ICP itself. The type of sample being analyzed is relevant to the effectiveness of the analysis but does not influence the operational characteristics of the ICP source.

The high-voltage power supply is thus the cornerstone feature that facilitates the generation and maintenance of the plasma, making it a critical component for the function of an ICP source.