Peak Voltage Vp Research Articles

Ozone production in nanosecond pulsed dielectric barrier discharge in synthetic air: the Effect of Pulse Width

This work investigates the effect of pulse width on the characteristics of electrical discharge, optical emission spectra and ozone production in a water electrode DBD using a modulable nanosecond pulsed power supply. Results show that the increase of pulse width tpw slightly increases the spectral intensity and the rotational temperature Trot, with a typical Trot of 299 ± 5 K at an applied peak voltage Vp of 18.6 kV and a tpw of 400 ns. The electronic excitation temperature Texc increases linearly with Vp and gradually with tpw, while the electron density ne shows a non-linear relationship with tpw. Results also show that an increase in tpw slightly increases the energy density. At low energy densities (SIE < 50 J/L), increasing tpw can improve ozone generation efficiency, reaching a maximum of 99.64 ± 0.87 g/kWh at 33.60 ± 1.53 J/L at a tpw of 900 ns. This investigation provides substantial insight into the nanosecond pulsed ozone production.

A radio frequency signal driver for quadrupole used in desktop orthogonal-injection time-of-flight mass spectrometer

According to the demand of home-made spectrometer, a radio frequency (RF) signal driver was developed. This RF signal driver is composed of signal generating circuit, signal amplification circuit and power output circuit, to drive the radio frequency quadrupole (RFQ). The designed RFQ is used to transfer ions generated in atmospheric pressure ion source to a home-made desktop orthogonal-injection time-of-flight mass analyzer. This signal driver is divided into low-frequency part and high-frequency part to support RFQ transferring ions of larger values (i.e., m/z=100–600) and smaller values (i.e., m/z=20–100) respectively. The low-frequency part of the RF signal driver can provide RF signals with resonance frequency of 1.43MHz, peak to peak voltage Vp–p of 0–1080V, and the high-frequency part can provide RF signals with resonance frequency of 2.05MHz, peak to peak voltage Vp–p of 0–520V. With the radio frequency signal driver described in this paper, ions in the range m/z 20–600 can be transmitted efficiently by RFQ.

Laser-induced voltage effects in c-axis inclined NaxCoO2 thin films

Laser-induced voltage effects in c-axis inclined NaxCoO2 thin films have been studied by using different laser sources with the wavelength ranging from ultraviolet to far infrared. Due to the transverse thermoelectric effect, a giant open-circuit voltage signal with the peak voltage Vp of about 16V is detected when the film surface is illuminated by an ultraviolet 308nm pulsed laser with the laser energy on the film is about 1.5mJ. Open-circuit voltage signals are also detected when the film is illuminated by the 532nm and 10.6μm lasers. The results demonstrate that the c-axis inclined NaxCoO2 thin film has a great potential application in the detection of laser radiations for wide spectral range, especially in the weak ultraviolet pulsed laser detection.

CaF2/Si/CaF2 double-barrier resonant-tunnelling diodes on Si substrates

CaF2/Si/CaF2 double-barrier resonant-tunnelling diodes have been fabricated by various processes with molecular beamepitaxy in SiO2 windows patterned on Si(111) substrates. Two types ofI–V characteristics with negative differential resistance (NDR) were observed in thetemperature range from 75 K up to about 200 K. The one is very stable in forward andbackward voltage sweeps, and, in contrast to earlier reports, it does not showany hysteresis or trapping effects. Typical diode parameters were: peak voltageVp = 0.7 V, peak-to-valleycurrent ratio P/V = 1.7 and peakcurrent density Ip = 2 mA cm−2 at105 K. The second is less stable and the NDR appeared only during forwardbias sweeps, possibly due to local trapping effects. But it has largerP/V ratios, the typicalparameters being: Vp = 1.2 V,P/V = 5 and Ip = 11 mA cm−2 at 77 K. The observed peak current densities of both NDR types are about five orders ofmagnitude higher than those reported previously for diodes with the similar structure. Weassume that an inhomogeneous Si quantum-well thickness with the current flow localized insmall regions of the diode area causes the observed variations in peak voltages,multiple NDR regions, peak spreading and exponentially rising background currents.

Voltage dependence of electron dynamics in high-power extended planar-anode diodes

Measurements confirm the ability of a numerical model to simulate basic features of electron flow and subsequent radiation output from EPA (extended planar-anode) diodes on HERMES III. HERMES III is a 19 MV, 700 kA, 25 ns electron accelerator. These diodes simultaneously terminate a coaxial MITL (magnetically insulated transmission line), and produce intense bursts of bremsstrahlung. The measurements and modeling show that (a) the EPA diode provides an impedance match to the MITL, (b) parapotential flow theory and the range of H− ions generated at the cathode can be used to measure the time-dependent voltage pulse and peak voltage VP, respectively, and (c) that ∼95% of the electrical energy transmitted to the diode can be converted to kinetic energy of electrons incident on bremsstrahlung targets. Further, it is demonstrated that the forward radiation fluence can be described by DA/Q=(76±11)Ṽ1.61 over the VP range 13–19 MV. DA, Q, and Ṽ refer to the forward radiation fluence measured in Mrad(CaF2) cm2, the incident charge measured in C, and the median current-weighted accelerating voltage measured in MV, respectively. The dependence on VP of the beam characteristics at the targets is shown and the detailed kinetic-energy distribution there is discussed.

The Determination of the Thickness of Anodic Al2O3 Film

To compare the properties of anodized aluminium oxide layers an easy thickness determination method is wanted. Crevecoeur and De Wit used a method expressing the thickness in terms of peak voltages obtained by forming again after annealing. The aim of the work described here is to relate the value of the peak voltage to the thickness of the layer measured by ellipsometry.On specimens formed in an aqueous solution of b oric acid and ammonium hydroxide the following relation is found between the thickness d (nm) and peak voltage Vp (volt):d = 1.020 Vp + (0.00044 ± 0.00011) Vp2. On specimens formed in a solution of ammonium pentaborate in ethylene glycol the squared Vp term is of a lower value. however when Vp is less than 150 V the above relation holds for layers formed in both electrolytes, the systematic error then being less than 1%.

Pyroelectric response to single infrared laser pulses in triglycine sulphate and strontium-barium niobate

Expressions are derived for the pyroelectric (PE) voltage response to single ir laser signals much shorter than the thermal time constant τT of the PE sample. It is shown both analytically and experimentally that when the electronic time constant τe is much shorter than the time characteristics of the signal, then the response exactly follows the signal and has a peak voltage Vp proportional to the load resistance RL. In the opposite case, the response rises as long as the signal persists, reaching a peak value proportional to absorbed energy but independent of RL, then decays exponentially with falltime τe ∝ RL, as long as τe≪τT.