Chemistry Reference
In-Depth Information
8.2.3.5.1 Plasma Sources
Whereas for sterilization/decontamination and surface treatment, application of low-
pressure plasma is possible, plasmas for direct therapeutic applications have to exist in
air environments at atmospheric pressure. Such plasmas must have gas temperatures
below 50
◦
C, and the electrical stress of the investigated tissue or of the treated body
must be negligible. Compilations of atmospheric plasmas for tissue processing are
given in [259,271]. According to the importance of plasma jets and DBDs for plasma
medical investigations, a brief description is given here of these plasma sources (see
also Section 3.8).
8.2.3.5.1.1 Atmospheric Pressure Plasma Jets
Plasma jets with various mechanical constructions with different electrical excitations
are presented in the literature [270]. An inert gas flow of some slm through a capillary
is excited by RF voltage and the generated plasma jet (diameter
1 mm) outside the
capillary can be used for treatment of the various targets (Figure 8.40a). A pulsed
operating of the plasma jet allows the decrease of the gas temperature in the jet below
30
◦
C [271]. The UV radiation of the plasma is an order of magnitude lower than the
minimal dose to produce sunburn in vivo [272]. These properties allow the application
of this tool for medical treatment. The application of the nanosecond-pulsed negative
∼
High-ohmic, HV DC
power supply, pulsed
-
+
Ar
Ar
HV-electrode
(hollow needle)
Capillary
(quartz)
Capillary
RF-electrode
(pin)
Gas channel
Hairline plasma
Plasma jet
(a)
(b)
FIGURE 8.40
(a) Atmospheric pressure RF excited plasma jet and (b) hairline nanosecond
pulsed negative DC corona plasma filament. (From Bussiahn, R. et al.,
Appl. Phys. Lett.
, 96,
143701, 2010.)
