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Optical and spectroscopic study of a supersonic flowing helium plasma: energy transport in the afterglow.

ABSTRACT: Flowing plasma jets are increasingly investigated and used for surface treatments, including biological matter, and as soft ionization sources for mass spectrometry. They have the characteristic capability to transport energy from the plasma excitation region to the flowing afterglow, and therefore to a distant application surface, in a controlled manner. The ability to transport and deposit energy into a specimen is related to the actual energy transport mechanism. In case of a flowing helium plasma, the energy in the flowing afterglow may be carried by metastable helium atoms and long-lived helium dimer ions. In this work a systematic investigation of the optical and spectroscopic characteristics of a supersonic flowing helium plasma in vacuum and its afterglow as function of the helium gas density is presented. The experimental data are compared with numerical modeling of the plasma excitation and helium dimer ion formation supported by a Computational Fluid Dynamic simulation of the helium jet. The results indicate that the plasma afterglow is effectively due to helium dimer ions recombination via a three-body reaction.

SUBMITTER: Brandi F

PROVIDER: S-EPMC7083830 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Optical and spectroscopic study of a supersonic flowing helium plasma: energy transport in the afterglow.

Brandi F F Labate L L Rapagnani D D Buompane R R Leva A di AD Gialanella L L Gizzi L A LA

Scientific reports 20200320 1

Flowing plasma jets are increasingly investigated and used for surface treatments, including biological matter, and as soft ionization sources for mass spectrometry. They have the characteristic capability to transport energy from the plasma excitation region to the flowing afterglow, and therefore to a distant application surface, in a controlled manner. The ability to transport and deposit energy into a specimen is related to the actual energy transport mechanism. In case of a flowing helium p ...[more]

PMID: 32198449

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Project description:BackgroundA previous multi-center clinical study of low energy (20% power), single-pass helium plasma dermal resurfacing (HPDR) showed positive results but did not fully reveal the true potential of this novel technology. A second multi-center clinical study, reported herein, was therefore undertaken to evaluate efficacy and safety of high energy (40%), double pass HPDR for treatment of facial rhytids (ClinicalTrials.gov Identifier: NCT04185909).MethodsFifty-five eligible subjects seeking improvement in facial rhytids were enrolled for study at one of four investigational sites. All subjects underwent full-face HPDR treatment. The forehead, nose, cheeks, and peri-oral treatment zones were treated at 40% power with two passes whereas the peri-orbital and jawline/mandibular zones were treated at 20% power (up to 40% for jawline/mandibular zone) and one or two passes. Photographic images of the face were captured using the VISIA-CR system. Three-month posttreatment Fitzpatrick Wrinkle and Elastosis Scale (FWS) scores were compared to baseline scores as determined by blinded independent photographic reviewers (IPRs) and study investigators.ResultsBlinded IPRs and study investigators observed a ≥1-point FWS improvement in 100% of subjects with mean change in IPR FWS from baseline to the 90-day visit of -3.6 (±1.2). 96.4% of subjects indicated "improvement" in appearance at the 90-day visit utilizing the modified Global Aesthetic Improvement Scale. Evaluation of VISIA-CR data revealed statistically significant improvements in wrinkles, brown spots, and pore counts. Overall, 269 Adverse Events in 55 subjects were reported; most were mild-moderate in severity (99.3%), anticipated (86.2%), and of relatively short duration with most having resolved within 30 days (60.6%) of treatment.ConclusionTreatment of facial rhytids with high energy, double pass HPDR as detailed herein enables a marked improvement in FWS that parallels or surpasses competing technologies. VISIA-CR analysis demonstrates additional improvements in skin quality with statistically significant quantitative improvements in brown spots and enlarged pores as well as wrinkles. Effective rhytid effacement combines with high subject satisfaction and few unanticipated adverse events for a reasonable benefit-risk ratio.

Project description:Background and objectivesA novel helium plasma device was evaluated for efficacy and safety for dermal resurfacing (ClinicalTrials.gov Identifier: NCT03286283). The helium plasma device delivers energy in a controlled, bimodal fashion that when compared with the nitrogen plasma predicate device in a porcine animal model demonstrated a more limited depth of thermal effect but a greater skin tissue contraction.Study design/materials and methodsFifty-five eligible subjects seeking improvement in facial rhytids were enrolled for study at one of three investigational sites. Most subjects underwent full-face treatment. Power levels were limited to 20% at peri-oral and peri-orbital areas-a level that correlates to an energy density 40% lower than the highest setting on the predicate device. Three-month post-treatment Fitzpatrick Wrinkle and Elastosis Scale (FWS) scores were compared with baseline scores as determined by blinded independent photographic reviewers (IPRs) and study investigators.ResultsBlinded IPRs observed a ≥1-point FWS improvement in 63.64% of subjects whereas study investigators noted a ≥1-point FWS improvement in 54 of 55 subjects (98.18%) of subjects. 90.9% of subjects indicated "improvement" in appearance utilizing the modified Global Aesthetic Improvement Scale. Subgroup analysis showed 1-point (±0.05) FWS improvement by IPRs and study investigators for Fitzpatrick Skin Types II and III, age≥62, two of three study sites, and post-treatment oral steroid use. Eighty Non-Serious Adverse Events in 39 subjects were reported, most of which resolved within 14 days or less. There were no Serious Adverse Events or Unanticipated Device Effects reported.ConclusionAt the modest power level studied, a significant improvement from a single pass helium plasma dermal resurfacing treatment was observable in most subjects by IPRs and investigators, and no serious adverse events were reported. The discrepancy between IPR and study investigator FWS improvement may be explained in part by the limitations of assessing two-dimensional photographs versus live in-person evaluation of subjects. Studies evaluating higher energy levels and/or multiple treatment passes are ongoing. Lasers Surg. Med. © 2020 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals, Inc.

Dataset Information

Optical and spectroscopic study of a supersonic flowing helium plasma: energy transport in the afterglow.

Publications

Optical and spectroscopic study of a supersonic flowing helium plasma: energy transport in the afterglow.

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