A plasma scalpel is one of the few applications of plasma medicine widely used in the clinic, but its ignition mechanism is poorly understood. This paper investigates the ignition phase of a plasma scalpel by obtaining the electrical waveforms, vaporization dynamics, plasma production and the plasma spectrum. Additionally, equivalent circuit and physical models are proposed based on the results. Two kinds of vapor layers are formed in plasma production. One is produced by Joule heating, which occurrs at the initial stage and the other is maintained by plasma heating at the stable discharge stage. When the plasma is generated, the vapor layer will become much thinner, leading to a significant increase in the electric field. The waveforms indicate the discharge has two kinds of patterns: asymmetric and symmetric patterns. The plasma intensity in the asymmetric is much stronger than the symmetric pattern. The fitted OH spectrum reveals that the gas temperature of the plasma can reach 2600 K, which can sustain the thin vapor layer. According to the broadening of the H_α line, the electron density is estimated to be about 7.1 10¹⁵ cm⁻³. Furthermore, when the stable vapor layer is formed, the impedance of the gap increases from 70 Ω to 2000 Ω when the plasma is established. The electron density is estimated again according to the plasma impedance to be about 10¹⁵–10¹⁶ cm⁻³.

等离子手术刀是在临床上广泛使用的等离子医学的少数应用之一，但其点火机理了解甚少。本文通过获取电波形，汽化动力学，等离子体产生和等离子体光谱来研究等离子体手术刀的点火阶段。此外，根据结果提出了等效电路和物理模型。在等离子体生产中形成两种蒸气层。一种是通过焦耳加热产生的，焦耳加热发生在初始阶段，另一种是通过等离子加热在稳定的放电阶段保持的。当产生等离子体时，蒸气层将变得更薄，从而导致电场的显着增加。波形表明放电有两种模式：不对称和对称模式。非对称中的等离子体强度比对称图案强得多。拟合的OH光谱表明，等离子体的气体温度可以达到2600 K，可以维持薄的蒸汽层。根据H的拓宽_α线，电子密度估计为约7.1 10 ¹⁵ cm ^-3。此外，当形成稳定的蒸汽层时，当建立等离子体时，间隙的阻抗从70Ω增加到2000Ω。再次根据等离子体阻抗估计电子密度约为10 ¹⁵ –10 ¹⁶ cm ^-3。