Two sources were used:
\nkINPen\u00ae MED \u2013 titled PJ for \u201cPlasma Jet\u201d in the manuscript and dataset. Settings are known from literature (~1MHz, 3-6 kV ptp) @ 1atm pressure, see e.g. https://iopscience.iop.org/article/10.1088/1361-6463/aab3ad.
Multijet \u2013 titled \"Plasma Jet Array System\" PJAS for the paper. Voltage and Frequency go along with kINPen (~1MHz, 3-6 kV ptp) @ 1atm pressure. The device was available in two construction variations with two different Valve Settings. The PJAS operates a gas switching technology, where valves switch the argon supply to the designated channels at different flushing times. The two variations were:
\nDevice I: having a homemade integrated circuit for the gas switching technology and the high voltage circuit receiving 66 V DC voltage from the base unit
\nDevice II: having a homemade discrete circuitry for the gas switching technology and the high voltage circuit receiving 60 V DC voltage from the base unit.
\nWith the two different settings on the valve opening:
\nSetting 1: a fixed value of 8 ms flushing per channel, resulting in programming delay of 8.2 ms up to 8.3 ms for the physical measurements
\nSetting 2: 30 ms valve opening and 2 ms delay before consecutive next valve opening.
The final combination of device and setting together with association to respective measurements is mentioned as e.g. \u2018PJAS I-2\u2019 for PJAS device I at setting 2.
\n", "procedure": "Plasma jets were flushed at least 15 minutes prior to performing diagnostics with argon, at least once per day. The device was mounted at a 0 mm distance by linear stages. For continous temperature measurements, motorized stages moved the temperature probe continously in front of a fixed plasma source.
\nFor ignition of plasma, argon was supplied at 5 bar pre pressure. Diagnostics and targets were mounted. The mass flow control (F-201 CM with E-8412-A-10, 5 slm range, Bronkhorst, NL) was set to the investigated flow range (2.5 slm or 5 slm). Then the plasma device was ignited.
Argon in ambient air at 1 atm and ~5atm pre-pressure; Temperature was around 20-25\u00b0C. Flow rate was controlled by mass flow control: F-201 CM with E-8412-A-10, 5 slm range, Bronkhorst, NL; despite the device having an internal flow control unit.
\n", "procedure": "Gas was flushed for at least 15 minutes before diagnostics initiation.
\n" }, "target": { "name": "copper, conductive metal mesh", "properties": "A copper plate was used as a target for the leakage current measurements.\r\nThere was no target used for the temperature measurements.\r\nThe target for the OES measurements was a conductive metal mesh. \r\nA dielectric surface was used as the target for gas species determination.", "procedure": "Targets were mounted in plate holders from Thorlabs. Mounted on linear stages. In case of leakage current, a motorized stage (x,y,z, Thorlabs) was used for figure 4a and 4c." }, "diagnostics": { "name": "Patient leakage current (PLC), fiber-optical temperature (FOT) probe, UV absorption spectroscopy, optical emission spectroscopy, OES", "properties": "Fiber optic temperature (FOT) analysis using a probe model TS5 (with 0.2 K precision, 0.55 mm out diameter) from Weidmann.
\nPatient leakage current (PLC) measured according DIN EN 60601-1-6 via UNIMET 800ST from Bender.
\nOptical emission spectroscopy (OES) measured with AvaSpec 3684 spectrometer (200 - 1100 nm range, ~2 nm resolution).
\nOzone and nitrogen dioxide density via gas detector system model APOA-360 for ozone and APNA-370 for nitrogen dioxide (both models from Horiba).
Temperature measurements.
\nIn order to acquire the temperature as a function of distance, a fiber-optical temperature (FOT) probe (0.2 K precision, 0.55 mm out diameter, model TS5, Weidmann, Germany) was placed in front of each channel 1 to 4 in succession, oriented to face away from the gas flow direction. The distance was controlled either with a motorized stage (MTS50/M-Z8 in the XYZ configuration with TSC 001 motor control, Thorlabs, USA) controlled with Kinesis (Version 1.14.37, Thorlabs, USA) for PJAS I-1 or manually with a linear stage for PJAS I-2 and II-2. The FOT probe was placed in front of each nozzle to measure the core of the outlet flow as well as sideways for radial profile measurements. Despite previous measurement routines, the present detection system was operated at constant movement and constant data acquisition of the FOT probe. Thereby, a more detailed profile of the temperature as a function of distance could be resolved [29]. For the temperature profile over distance, the motorized stage moves at a constant velocity of 0.15 mm s\u22121 with the FOT probe moving either constantly away or toward the capillary orifice. The profile for each channel of the PJAS as well as the PJ was acquired. For the overall temperature map of the PJAS, the FOT probe also moved continuously sideways
\nover the full array of channels with a velocity of 0.5 mm s\u22121. The distance to the outlet was stepwise increased at 1 mm resolution.
Patient leakage current.
\nIn order to determine the PLC, a similar operation of the motorized stages was used. A copper strip on a plastic surface serves as a counter electrode. The counter electrode was connected via an RC-circuit (according to DIN EN 60 601-1-6 via UNIMET\u00ae 800ST, Bender GmbH & Co. KG, Gruenberg, Germany) to ground [30, 31]. The motorized stage moves the grounded electrode toward the capillary orifice at a velocity of 0.1 mm s\u22121 from a distance of 10 mm toward 1 mm. The measurements were performed for all four channels simultaneously and for individual channels as well. For the latter setting, the grounded electrode is shielded with a plastic part except for an access area of 1 \u00d7 1 cm\u22122 in front of the investigated channel. Data acquisition for temperature and PLC measurements
\nwas performed with the homemade Python code PlaDinSpec (Python 3.8).
Optical emission spectroscopy.
\nOES was employed to identify the emitting species as a function of distance by the PJAS. All OES measurements were performed with the PJ impinging on a grounded metallic mesh over a quartz plate similar to a setup described previously [32]. A spectrometer (Avantes, AvaSpec 3648, 200\u20131100 nm range, \u223c2 nm resolution, 300 line mm\u22121 grating, blazed at 300 nm, deep-UV-detector coated CCD linear array) with an optical fiber connected to a cosine corrector was employed for OES measurements. The optical fiber was placed in front of each PJAS channel in succession at 80 ms integration time and 100 averages. The OES system was calibrated for absolute light intensity measurements. The distance between the plasma outlet and target was varied from 3 mm to 25 mm.
UV absorption spectroscopy
\nLong-lasting reactive species in the gas phase were measured using a commercial gas detector system (model APOA-360 for O3 and APNA-370 for NO2, Horiba, Japan). The PJAS was placed in front of the detection tube (end on, 0\u25e6) at a distance of up to 100 cm. In addition, measurements were performed with the PJAS at an 90\u25e6 impact angle on a dielectric plate at 10 mm distance and the detection tube placed at an angle of 45\u25e6 or 90\u25e6 toward the PJAS at a distance of up to 100 cm away (see further [28]).