Showing papers on "Pulse repetition frequency published in 2012"
TL;DR: In this paper, an improved processing method was proposed for the Micro Rain Radar 2 (MRR) which is especially suited for snow observations and provides reliable values of effective reflectivity, Doppler velocity and spectral width.
Abstract: . The Micro Rain Radar 2 (MRR) is a compact Frequency Modulated Continuous Wave (FMCW) system that operates at 24 GHz. The MRR is a low-cost, portable radar system that requires minimum supervision in the field. As such, the MRR is a frequently used radar system for conducting precipitation research. Current MRR drawbacks are the lack of a sophisticated post-processing algorithm to improve its sensitivity (currently at +3 dBz), spurious artefacts concerning radar receiver noise and the lack of high quality Doppler radar moments. Here we propose an improved processing method which is especially suited for snow observations and provides reliable values of effective reflectivity, Doppler velocity and spectral width. The proposed method is freely available on the web and features a noise removal based on recognition of the most significant peak. A dynamic dealiasing routine allows observations even if the Nyquist velocity range is exceeded. Collocated observations over 115 days of a MRR and a pulsed 35.2 GHz MIRA35 cloud radar show a very high agreement for the proposed method for snow, if reflectivities are larger than −5 dBz. The overall sensitivity is increased to −14 and −8 dBz, depending on range. The proposed method exploits the full potential of MRR's hardware and substantially enhances the use of Micro Rain Radar for studies of solid precipitation.
141 citations
TL;DR: In this article, the authors demonstrate the use of graphene oxide as a saturable absorber in the passive mode-locking of a diode pumped Tm3+-doped laser.
Abstract: For the first time of our knowledge, we demonstrate the graphene oxide as a saturable absorber (SA) in the passive mode-locking of a diode pumped Tm3+-doped laser. Broadly spectral region sub-10 ps mode-locking in a Tm:YAlO3 (Tm:YAP) laser near 2 μm were obtained. With a pump power of 8.64 W, the average output power of 268 mW with the maximum pulse energy of 3.7 nJ at the pulse repetition frequency (PRF) of 71.8 MHz was obtained.
110 citations
TL;DR: In this article, a 2\mu m ultrafast solid-state Tm:Lu2O3 laser, mode-locked by single-layer graphene, generates transform-limited ~410fs pulses, with a spectral width 11.1nm at 2067nm.
Abstract: We report a 2\mu m ultrafast solid-state Tm:Lu2O3 laser, mode-locked by single-layer graphene, generating transform-limited~410fs pulses, with a spectral width~11.1nm at 2067nm. The maximum average output power is 270mW, at a pulse repetition frequency of 110MHz. This is a convenient high-power transform-limited laser at 2\mu m for various applications, such as laser surgery and material processing.
110 citations
TL;DR: In this article, a photonic-based scheme was proposed for generating phase-coded RF pulses suitable for coherent radar systems with pulse compression techniques, which is capable of flexibly generating software-defined phase-modulated RF pulses with high stability, even at very high carrier frequency, using only a single commercial device.
Abstract: A novel and flexible photonics-based scheme is proposed for generating phase-coded RF pulses suitable for coherent radar systems with pulse compression techniques. After selecting two modes from a mode-locked laser (MLL), the technique exploits an optical in-phase/quadrature modulator driven by a low-sample rate and low-noise direct digital synthesizer to modulate the phase of only one mode. The two laser modes are then heterodyned in a photodiode, and the RF pulse is properly filtered out. The scheme is experimentally validated implementing a 4-bit Barker code and a linear chirp on radar pulses with a carrier frequency of about 25 GHz, starting from an MLL at about 10 GHz. The measures of phase noise, amplitude- and phase-transients, and autocorrelation functions confirm the effectiveness of the scheme in producing compressed radar pulses without affecting the phase stability of the optically generated high-frequency carriers. An increase in the radar resolution from 150 to 37.5 m is calculated. The proposed scheme is capable of flexibly generating software-defined phase-modulated RF pulses with high stability, even at very high carrier frequency, using only a single commercial device with potentials for wideband modulation. It can therefore allow a new generation of high-resolution coherent radars with reduced complexity and cost.
96 citations
TL;DR: An efficient Q-switched Ho(3+)Pr(3+)-doped fluoride fiber laser, producing a peak power of 77 W, with pulse width of 78 ns, with continuous tunability of the pulse repetition frequency from 40 to 300 kHz is reported.
Abstract: We report an efficient Q-switched Ho3+Pr3+-doped fluoride fiber laser, producing a peak power of 77 W, with pulse width of 78 ns. A slope efficiency of 20% with respect to the launched pump power was achieved. A TeO2 acousto-optic modulator allowed continuous tunability of the pulse repetition frequency from 40 to 300 kHz.
90 citations
TL;DR: In this article, a nano second pulsed dielectric barrier discharge plasma reactor has been investigated for conversion of heavy naphtha, and the effect of applied voltage, pulse frequency and inner electrode material has been examined on the quantity and quality of products.
78 citations
TL;DR: In this article, constrained optimization techniques are used to generate spectrally compliant wideband radar waveforms while maintaining a constant amplitude or an otherwise specified pulse envelope, and mismatched filters are created to reduce the high temporal sidelobes.
Abstract: It has been demonstrated that constrained optimization techniques can be used to generate spectrally-compliant wideband radar waveforms. Essential features of this approach include the following: 1) Wide spectral notches can be introduced into wideband radar waveforms while maintaining a constant amplitude or an otherwise specified pulse envelope. 2) Pre-distortion of the waveform, which is included in the waveform generator coefficients, should be able to preserve the spectral notches at the transmitter output. 3) Mismatched filters can be created to significantly reduce the high temporal sidelobes that are created by including a significant amount of spectral notching. These filters incur loss resolution penalties similar to those of conventional range sidelobe weighting functions applied to conventional waveforms.
71 citations
TL;DR: In this article, a Tm-doped Lu2O3 ceramic laser was used to achieve femtosecond mode locking using an ion-implanted InGaAsSb quantum-well-based SESAM.
Abstract: Femtosecond mode locking of a Tm-doped Lu2O3 ceramic laser is reported. Transform-limited pulses as short as 180 fs are generated at 2076 nm with an average output power of 400 mW and a pulse repetition frequency of 121.2 MHz. An output power up to 750 mW can be reached at the somewhat longer pulse duration of 382 fs. Femtosecond pulse generation is realized in the 2030-2100 nm spectral range. Passive mode locking was achieved using an ion-implanted InGaAsSb quantum-well-based SESAM.
69 citations
TL;DR: Key parameters in microbubble-seeded flow conditions were matched with specific types, magnitudes, distributions, and durations of cavitation; this may help in understanding empirically observed in vivo phenomena and guide future pulse sequence designs.
Abstract: Ultrasound and microbubble-based therapies utilize cavitation to generate bioeffects, yet cavitation dynamics during individual pulses and across consecutive pulses remain poorly understood under physiologically relevant flow conditions. SonoVue(®) microbubbles were made to flow (fluid velocity: 10-40 mm/s) through a vessel in a tissue-mimicking material and were exposed to ultrasound [frequency: 0.5 MHz, peak-rarefactional pressure (PRP): 150-1200 kPa, pulse length: 1-100,000 cycles, pulse repetition frequency (PRF): 1-50 Hz, number of pulses: 10-250]. Radiated emissions were captured on a linear array, and passive acoustic mapping was used to spatiotemporally resolve cavitation events. At low PRPs, stable cavitation was maintained throughout several pulses, thus generating a steady rise in energy with low upstream spatial bias within the focal volume. At high PRPs, inertial cavitation was concentrated in the first 6.3 ± 1.3 ms of a pulse, followed by an energy reduction and high upstream bias. Multiple pulses at PRFs below a flow-dependent critical rate (PRF(crit)) produced predictable and consistent cavitation dynamics. Above the PRF(crit), energy generated was unpredictable and spatially biased. In conclusion, key parameters in microbubble-seeded flow conditions were matched with specific types, magnitudes, distributions, and durations of cavitation; this may help in understanding empirically observed in vivo phenomena and guide future pulse sequence designs.
57 citations
TL;DR: This paper first establishes the radar signal model of the spinning missile during flight, and then extracts the micro-Doppler modulation frequency through analysis of the periodic structure of the resulting spectrogram (short-time Fourier transform (STFT)) - i.e., the time-frequency distribution (TFD).
54 citations
Patent•
14 Feb 2012
TL;DR: In this paper, an all fiber optic laser-based scanning system for real-time terrain mapping under degraded visual conditions is described, where a laser output is modulated to achieve a desired pulse width and pulse repetition frequency (PRF) and the modulated signal is amplified.
Abstract: An all fiber optic laser based scanning system for real time terrain mapping under degraded visual conditions is disclosed. A laser output is modulated to achieve a desired pulse width and pulse repetition frequency (PRF) and the modulated signal is amplified. The amplified optical signals are split into N channels that correspond to N elements of an optically phased array that steers light by modulating the phase of light entering and exiting the optical system. By applying a linear phase shift across the beam's wave front, the light propagating along the system's optical axis is steered to an off-axis angle. A real time map of an underlying terrain is accomplished by sweeping the N channel array across the terrain while collecting range information from each scan grid.
TL;DR: In this article, a two-frequency, pulsed capacitively coupled plasma sustained in Ar and Ar/CF4/O2 mixtures is discussed with results from a twodimensional plasma hydrodynamics model.
Abstract: The fluxes of radicals and ions to the wafer during plasma processing of microelectronics devices determine the quality of the etch or deposition. These fluxes are largely controlled by controlling the electron energy distribution function f( e)which determines the dissociation patterns of feedstock gases. In quasi-steady state operation, an equilibrium condition for f( e) results from a real time balance between electron sources and sinks. Using pulsed power, electron sources and sinks do not need to instantaneously balance—they only need to balance over the longer pulse period. This provides additional leverage to customize f( e). In this paper, the f( e)in a two-frequency, pulsed capacitively coupled plasma sustained in Ar and Ar/CF4/O2 mixtures are discussed with results from a two-dimensional plasma hydrodynamics model. The f( e)are obtained from a Monte Carlo simulation which includes electron‐electron collisions. We found that the f( e)and rate coefficients can be controlled by pulse repetition frequency (PRF) and duty cycle (DC) of the pulsed power in a manner not otherwise easily attainable using continuous excitation. The tail of the f( e)is enhanced with smaller PRF and DC in order to compensate for the electron losses during the power-off portion of the cycle. (Some figures may appear in colour only in the online journal)
TL;DR: A prototype ultrawideband radar which operates from 500 MHz to 3 GHz with a nominal resolution of 6 cm in air is described and range gating is used to improve the system dynamic range.
Abstract: We describe a prototype ultrawideband radar. We show how the system was designed and how the hardware was developed for the radar prototype. Waveform generation, radar parameters, and signal processing for the stepped frequency waveform are discussed. The radar operates from 500 MHz to 3 GHz with a nominal resolution of 6 cm in air. The advantage of the stepped frequency approach over an impulse radar is better matching between the transmitted waveform and the receiver. We use range gating to improve the system dynamic range. The advantages are illustrated with laboratory measurements and field measurements from glacial ice and permafrost in Svalbard, showing penetration depths of 11 m. Antennas which do not require contact with the ground were developed and used in the experiments.
TL;DR: In this paper, the discharge current waveform is highly dependent on both the pulse repetition frequency and discharge voltage and the current increases with decreasing frequency or voltage, which is attributed to an increase in the secondary electron emission yield during the self-sputtering phase of the pulse, as an oxide forms on the target.
Abstract: The discharge current–voltage–time waveforms are studied in the reactive Ar/O2 high power impulse magnetron sputtering discharge with a titanium target for 400 μs long pulses. The discharge current waveform is highly dependent on both the pulse repetition frequency and discharge voltage and the current increases with decreasing frequency or voltage. The authors attribute this to an increase in the secondary electron emission yield during the self-sputtering phase of the pulse, as an oxide forms on the target.
TL;DR: The design and performance characteristics of a third generation MPD laser transmitter with enhanced laser performance over the previous generation DIAL system are described.
Abstract: An all diode-laser-based micropulse differential absorption lidar (DIAL) laser transmitter for tropospheric water vapor and aerosol profiling is presented. The micropulse DIAL (MPD) transmitter utilizes two continuous wave (cw) external cavity diode lasers (ECDL) to seed an actively pulsed, overdriven tapered semiconductor optical amplifier (TSOA). The MPD laser produces up to 7 watts of peak power over a 1 µs pulse duration (7 µJ) and a 10 kHz pulse repetition frequency. Spectral switching between the online and offline seed lasers is achieved on a 1Hz basis using a fiber optic switch to allow for more accurate sampling of the atmospheric volume between the online and offline laser shots. The high laser spectral purity of greater than 0.9996 coupled with the broad tunability of the laser transmitter will allow for accurate measurements of tropospheric water vapor in a wide range of geographic locations under varying atmospheric conditions. This paper describes the design and performance characteristics of a third generation MPD laser transmitter with enhanced laser performance over the previous generation DIAL system.
TL;DR: A novel TMS device with a full-bridge circuit topology incorporating four insulated-gate bipolar transistor modules and one energy storage capacitor to generate arbitrary waveforms that can be adjusted with respect to pulse width, polarity, and intensity is described.
Abstract: Transcranial magnetic stimulation (TMS) is able to noninvasively excite neuronal populations due to brief magnetic field pulses. The efficiency and the characteristics of stimulation pulse shapes influence the physiological effect of TMS. However, commercial devices allow only a minimum of control of different pulse shapes. Basically, just sinusoidal and monophasic pulse shapes with fixed pulse widths are available. Only few research groups work on TMS devices with controllable pulse parameters such as pulse shape or pulse width. We describe a novel TMS device with a full-bridge circuit topology incorporating four insulated-gate bipolar transistor (IGBT) modules and one energy storage capacitor to generate arbitrary waveforms. This flexible TMS (flexTMS) device can generate magnetic pulses which can be adjusted with respect to pulse width, polarity, and intensity. Furthermore, the equipment allows us to set paired pulses with a variable interstimulus interval (ISI) from 0 to 20 ms with a step size of 10 μs. All user-defined pulses can be applied continually with repetition rates up to 30 pulses per second (pps) or, respectively, up to 100 pps in theta burst mode. Offering this variety of flexibility, flexTMS will allow the enhancement of existing TMS paradigms and novel research applications.
TL;DR: It is shown that this type of radar receiver, specifically linearly frequency modulated CW (LFMCW) radar and stretch processing radar, closely approaches matched filtering, and so can be assumed to have the same well-understood properties and advantages as that class of detectors.
Abstract: It is widely assumed that dechirp-on-receive linearly frequency modulated radar is a form of matched filtering, although this is rarely demonstrated. In this correspondence it is shown that this type of radar receiver, specifically linearly frequency modulated CW (LFMCW) radar and stretch processing radar, closely approaches matched filtering, and so can be assumed to have the same well-understood properties and advantages as that class of detectors.
TL;DR: In this article, a fully integrated 24GHz CMOS ultra-wideband (UWB) radar transmitter for short-range automotive application is presented, where a pulse compression technique using binary phase code is adopted.
Abstract: A fully integrated 24-GHz CMOS ultra-wideband (UWB) radar transmitter for short-range automotive application is presented. For high-range resolution and improved signal-to-noise ratio, a pulse compression technique using binary phase code is adopted. Design issues of UWB radar transmitter are investigated based on fundamental pulse theory. A pulse former, which operates as a switch to generate a pulse modulated carrier signal and a bi-phase modulator for pulse compression, is proposed. The proposed transmitter achieves 4-GHz output signal bandwidth, which means a minimum range resolution of 7.5 cm, and the total dc power dissipation is 63 mW.
Patent•
25 Sep 2012
TL;DR: In this paper, a method and apparatus that reduces laser speckle by using stimulated Raman scattering in an optical fiber is described, which is adjusted to control aspects of the laser light such as color or despeckling.
Abstract: A method and apparatus that reduces laser speckle by using stimulated Raman scattering in an optical fiber. The pulse repetition frequency of the laser is adjusted to control aspects of the laser light such as color or despeckling. In DLP projection systems, an optical monitor may be used to send information to a bit sequence, and the bit sequence may control the pulse repetition frequency of the laser based on the optical monitor signal.
TL;DR: There is no evidence of benefit from faster stimulation rates in the perception of amplitude modulation in cochlear implant systems, even with very fast stimulation rates tested over a wide range of modulation frequencies and with two different tasks.
Abstract: OBJECTIVES: A major focus of recent attempts to enhance cochlear implant (CI) systems has been to increase the rate at which pulses are delivered to the electrode array. One basis for these attempts has been the expectation that faster stimulation rates would lead to an enhanced representation of temporal modulation information. However, there is recent physiological and behavioral evidence to suggest that the reverse may be the case. Here, the effects of stimulation rate on the perception of amplitude modulation were assessed using both modulation detection and modulation frequency discrimination tasks for a range of pulse rates extending considerably higher than the highest rate tested in previous studies and for different speech-relevant modulation frequencies. DESIGN: Detection of sinusoidal amplitude modulation was assessed in five CI users using monopolar pulse trains presented to a single electrode at rates of 482, 723, 1447, 2894, and 5787 pulses per second (pps). Adaptive procedures were used to find the minimal detectable modulation depth at modulation frequencies of 10 and 100 Hz and at carrier levels of 25%, 50%, and 75% of the electrode's dynamic range. Discrimination of modulation frequency was examined for the same range of pulse rates for the highest carrier level. Similar adaptive procedures determined the minimum increase in modulation frequency that could be detected relative to reference modulation frequencies of 10, 100, and 200 Hz. In both tasks, level roving was implemented to minimize possible loudness cues. RESULTS: Consistent with previous evidence, modulation detection thresholds were better for higher carrier levels and lower modulation frequencies. When modulation depth at threshold was expressed in terms of the ratio of the depth of the modulation and the carrier level in dB (i.e., 20 log m), performance was significantly better at lower pulse rates. However, when modulation depth was expressed relative to dynamic range, the effect of pulse rate was no longer significant, reflecting the fact that dynamic range increases with pulse rate. Modulation frequency discrimination clearly worsened with increasing modulation frequency, but there was no significant effect of pulse rate. CONCLUSIONS: In contrast to some recent evidence, no clearly harmful effect of higher pulse rates on modulation perception was found. However, even with very fast stimulation rates, tested over a wide range of modulation frequencies and with two different tasks, there is no evidence of benefit from faster stimulation rates in the perception of amplitude modulation.
TL;DR: In this paper, the effects of applied voltage amplitude, voltage polarity, pulse repetition frequency, and barrier dielectric on discharge characteristics are investigated, respectively, by measuring voltage and current waveforms.
TL;DR: This paper describes an operational pulse Doppler radar imaging system for indoor target localization and classification, and shows how a target's micro-Doppler signature can be processed when ultra-wideband (UWB) waveforms are employed.
Abstract: In this paper, we describe an operational pulse Doppler radar imaging system for indoor target localization and
classification, and show how a target's micro-Doppler signature (μDS) can be processed when ultra-wideband (UWB)
waveforms are employed. Unlike narrowband radars where time-frequency signal representations can be applied to
reveal the target time-Doppler frequency signatures, the UWB system permits joint range-time-frequency representation
(JRTFR). JRTFR outputs the data in a 3D domain representing range, frequency, and time, allowing both the μDS and
high range resolution (HRR) signatures to be observed. We delineate the relationship between the μDS and the HRR
signature, showing how they would form a complimentary joint feature for classification. We use real-data to
demonstrate the effectiveness of the UWB pulse-Doppler radar, combined with nonstationary signal analyses, in gaining
valuable insights into human positioning and motions.
TL;DR: In this article, the initiation and development of a streamer-like plasma jet generated in a singleelectrode dielectric barrier configuration at atmospheric pressure was investigated using spatially and temporally resolved emission spectroscopy and wide-bandwidth current measurements.
Abstract: We investigate the initiation and development of a streamer-like plasma jet generated in a single-electrode dielectric barrier configuration at atmospheric pressure. The influence of dielectric boundary conditions on discharge propagation dynamics, morphology and current distribution was studied using spatially and temporally resolved emission spectroscopy and wide-bandwidth current measurements. A Phantom high-frame-rate camera system was used to visualize discharge inception as a function of pulse repetition frequency, which was varied between 1 and 20 kHz. At discharge inception, with the copper ring anode located 20 mm behind the capillary tip, the discharge propagated along the 2 mm diameter inner wall of the glass capillary regardless of pulse repetition frequency. The steady-state morphology remained annular below 6 kHz, but gradually transitioned to an axial morphology with the expansion of a dark wall sheath towards the anode as the pulse repetition frequency was increased to 10 kHz. In the axial mode, the ionization front steadily decelerated with a corresponding decrease in peak emission intensity, while emission from the residual plasma channel increased. This indicated a dynamic redistribution of electric potential from the ionization front into the residual plasma channel that was attributed to charge accumulation on the dielectric surface between discharge pulses.
TL;DR: In this brief, a 0-960-MHz/3.1-5-GHz dual-band ultra low-power impulse-radio ultrawideband transmitter is presented and its integrated circuit is fabricated using a 130-nm CMOS process with the core die area of 0.1 mm2.
Abstract: In this brief, a 0-960-MHz/3.1-5-GHz dual-band ultra low-power impulse-radio ultrawideband transmitter is presented. The pulse transmitter integrated circuit is fabricated using a 130-nm CMOS process with the core die area of 0.1 mm2. At 1-MHz pulse repetition frequency, the power consumption values are measured in the lower and the upper bands as 5.6 and 31 μW, respectively. The lower and the upper band “off-time” power consumptions of the transmitter are 0.36 and 1.7 μW, respectively. The dc-to-radio-frequency conversion efficiencies are 11.1% in the lower band and 4.8% in the upper band.
07 May 2012
TL;DR: In this paper, the authors analytically derive the return signal model of a target rectilinearly moving at invariable speed, and devise a new algorithm to estimate the velocity and reconstruct the image of target.
Abstract: Linearly stepped frequency (LSF) waveforms are widely equipped in inverse synthetic aperture radar (ISAR), where the frequency is linearly altered with a fixed frequency step in each burst. ISAR employing randomized stepped frequency (RSF) modulation improves the rang-Doppler resolution, widens the unambiguous Doppler window, and enhances performance in electronic counter-countermeasures (ECCM). However in RSF radar, range profiles can severely spread when the radial velocity is unknown. In this paper, we analytically derive the return signal model of a target rectilinearly moving at invariable speed, and devise a new algorithm to estimate the velocity and reconstruct the image of target. Numerical results demonstrate the effectiveness of the algorithm.
TL;DR: The dynamics of passive phase locking is studied, and the established time of phase locking of two pulsed amplifiers is at least 10 cavity round trips in the all-optical feedback loop.
Abstract: A passive coherent beam combination of two nanosecond amplifiers is realized by using an all-optical feedback loop. The width of the combined pulses is 9.7 ns, and the pulse repetition frequency is 2.023 MHz. With the least mismatch between pulse period and time of the cavity round trip in our loop, the visibility of far-field coherent patterns is more than 71%. The dynamics of passive phase locking is studied, and the established time of phase locking of two pulsed amplifiers is at least 10 cavity round trips in the all-optical feedback loop.
TL;DR: It is demonstrated that with pulsed ultrasound, particles and/or cells levitate in suspension, as with continuous ultrasound, and the aggregation rate can be modified in a controlled manner, thus allowing for higher acoustic energies than those currently employed with continuously ultrasound.
Proceedings Article•
01 Oct 2012
TL;DR: The CRLB for an FMCW radar with phase evaluation is derived and different algorithms reaching the CRLBs are presented.
Abstract: The FMCW radar technology offers the possibility to achieve very high target accuracy mainly limited by the SNR. In this paper the CRLB for an FMCW radar with phase evaluation is derived and different algorithms reaching the CRLB are presented. The algorithms are tested in a simulation and the simulation results are compared with measurement results of an existing FMCW radar. The used algorithms are the zero padded FFT, the chirp z-transform and the esprit algorithm. The FMCW radar works in the K-band with a center frequency of 24 GHz and a bandwidth of 1 GHz. An accuracy of 65 μm is reached.
TL;DR: In this article, a magnetic pulse compressor was used to repetitively deliver 70 ns-long high voltage pulses to cultured HeLa cells in a 4 mm-gap cuvette electrode.
Abstract: This study elucidates the influence of the pulsing sequence of repetitive nanosecond pulsed electric fields on the viability of human cancer (HeLa S3) cells. A magnetic pulse compressor was used to repetitively deliver 70 ns-long high voltage pulses to cultured HeLa cells in a 4 mm-gap cuvette electrode. The repetition frequency was varied between 0.01 and 250 pulses per second (pps), corresponding to interval from 100 to 0.004 s, respectively. The electric field and the number of pulses were fixed at 25 kV/cm and 25, respectively, which is a sub-lethal condition for the cells. Propidium iodide was used to identify dead cells in the population. Statistical analysis of a cell death ratio in approximately 5000 cells was performed using a flow cytometer. This experiment shows repetition frequency affects cell viability even with identical intra-medium electrical energy expenditure. The dead cell ratio was increased with decreasing pulse repetition frequency down to 0.33 pps, whereas the ratio is decreased with decreasing frequency below 0.1 pps. Since the resealing mechanism of nano-pores caused by the application of ns pulse lasts for a minute, the dependence of the cell viability on the pulsing sequence might be associated with time constants of biological processes related to recovery from field-induced damage.