Understanding the Significance and Accuracy of Plasma Excitation Temperature Using the Boltzmann Plot Method

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This study addresses crucial factors often overlooked in the literature and provides guidelines for improving the accuracy and interpretation of temperature measurements in plasma diagnostics.

Alessandro De Giacomo, a researcher from the University of Bari in Italy, sheds light on the significance, precision, trueness, and accuracy of the excitation temperature obtained through the Boltzmann plot method. Published in Spectrochimica Acta Part B: Atomic Spectroscopy, the paper addresses several critical aspects often overlooked in the current literature, providing in-depth analysis and guidelines for the proper use and interpretation of Boltzmann plot-derived temperature values (1).

The excitation temperature is a vital parameter in plasma spectroscopy, providing insights into the energy distribution of excited atoms or ions. The Boltzmann plot method is commonly employed to determine this temperature by analyzing the relative intensities of spectral lines. However, certain factors can significantly impact the accuracy and reliability of the obtained temperature values, which are crucial for precise plasma diagnostics.

De Giacomo's research highlights several important considerations that are often neglected in the current literature. The study explores the effect of the signal-to-noise ratio (S/N) on the accuracy of the Boltzmann plot method, emphasizing the need for careful signal optimization and noise reduction techniques. Additionally, the paper clarifies the distinction between the average temperature and the time- and space-integrated temperature, known as the apparent temperature, which is essential for accurate temperature characterization in different plasma regions.

To demonstrate the significance of these factors, both experimental simulations and real experiments are utilized. The research findings underline the sensitivity of the Boltzmann plot method to various parameters and provide insights into the potential sources of errors and uncertainties. By addressing these issues, researchers can enhance the accuracy and reliability of plasma excitation temperature measurements, enabling more robust plasma diagnostics and analysis.


The paper concludes with practical guidelines for the appropriate use of the Boltzmann plot method and the interpretation of temperature values. These guidelines aim to assist researchers in obtaining accurate and meaningful temperature measurements, facilitating more precise plasma characterization and advancing our understanding of plasma processes.

This research contributes to the field of plasma spectroscopy by highlighting the significance of the Boltzmann plot method and providing valuable insights into the precision, trueness, and accuracy of excitation temperature determination. By considering the discussed factors and following the proposed guidelines, researchers can optimize their plasma diagnostics and achieve more reliable temperature measurements in various plasma environments.


(1) Bousquet, B.; Gardette, V.; Motto Ros, V.; Gaudiuso, R.; Dell’Aglio, M.; De Giacomo, A. Plasma excitation temperature obtained with Boltzmann plot method: Significance, precision, trueness and accuracy. Spectrochimica Acta Part B: At. Spectrosc. 2023, 204, 106686. DOI: 10.1016/j.sab.2023.106686