Wide Pulse Width Research Articles

Collimation, compression and acceleration of isotropic hot positrons by an intense vortex laser

Laser-driven positron sources, characterized by short pulse width, small focal spot and high energy, are promising for potential applications, e.g. electron–positron collider and positron annihilation spectroscopy. However, the broad divergence angle and wide pulse width during the laser-driven positron transport are extremely unfavorable for achieving high spatiotemporal resolution. In this paper, we propose a novel method to manipulate the positrons by using a left-hand circularly-polarized Laguerre–Gaussian (LG) laser pulse. Using the LG laser with a intensity of and a duration of a few cycles, three-dimensional particle-in-cell simulations reveal that isotropic hot positrons can be effectively captured, collimated, compressed, and accelerated due to the unique field structure of the LG laser. A high-quality positron bunch is obtained with a peak divergence angle of 1∘, an average pulse duration of 0.5 fs, a maximum energy of 450 MeV, and a density of 70 times that of the initial electron source. A damping vibration model is also formulated to explain qualitatively the quality improvement of the positrons.

Breakthrough the physical barrier on spatial resolution in Raman distributed fiber sensing using chaotic correlation demodulation

Raman distributed optical fiber temperature sensors possess the unique capability of measuring spatial environmental temperatures, which can be of great interest in several fields of application. The key physics barrier to spatial resolution for most optical time-domain reflection (OTDR) systems is the positioning principle of pulse-time-flight. It obtains the spatial resolution of the existing Raman distributed optical fiber temperature sensor, with the kilometer-level sensing distance being limited to the meter-level. Here, we propose a chaotic laser Raman distributed optical fiber temperature sensing scheme that replaces the traditional OTDR positioning principle used for more than 40 years with the chaotic correlation positioning principle. The proposed scheme possesses the characteristics of the chaos Raman scattering light excited by the chaos signal along the sensing fiber. A novel measurement mechanism based on chaotic time-domain differential reconstruction and chaotic correlation demodulation is developed, and a relationship between the temperature variation information and the chaotic correlation peak is experimentally demonstrated. Importantly, the proposed optics mechanism scheme overcomes the physics limitation of the effect of a wide pulse width on sensing spatial resolution; its spatial resolution is optimized from 50 to 0.3 m under the modulation of a 500 ns pulse width. This scheme provides a new concept for chaos optics and fiber sensing research.

2.1 m, high-energy dissipative soliton resonance from a holmium-doped fiber laser system

Abstract We propose a 2.1 μm high-energy dissipative soliton resonant (DSR) fiber laser system based on a mode-locked seed laser and dual-stage amplifiers. In the seed laser, the nonlinear amplifying loop mirror technique is employed to realize mode-locking. The utilization of an in-band pump scheme and long gain fiber enables effectively exciting 2.1 μm pulses. A section of ultra-high numerical aperture fiber (UHNAF) with normal dispersion and high nonlinearity and an output coupler with a large coupling ratio are used to achieve a high-energy DSR system. By optimizing the UHNAF length to 55 m, a 2103.7 nm, 88.1 nJ DSR laser with a 3-dB spectral bandwidth of 0.48 nm and a pulse width of 17.1 ns is obtained under a proper intracavity polarization state and pump power. The output power and conversion efficiency are 0.233 W and 4.57%, respectively, both an order of magnitude higher than those of previously reported holmium-doped DSR seed lasers. Thanks to the high output power and nanosecond pulse width of the seed laser, the average power of the DSR laser is linearly scaled up to 50.4 W via a dual-stage master oscillator power amplifier system. The 3-dB spectral bandwidth broadens slightly to 0.52 nm, and no distortion occurs in the amplified pulse waveform. The corresponding pulse energy reaches 19.1 μJ, which is the highest pulse energy in a holmium-doped mode-locked fiber laser system to the best of our knowledge. Such a 2.1 μm, high-energy DSR laser with relatively wide pulse width has prospective applications in mid-infrared nonlinear frequency conversion.

Recognition of centimeter-level length changes using the intensity of probe light in BOTDA

We proposed a method based on the Brillouin optical time domain analysis (BOTDA) system to demodulate the length changes of the heating region using the intensity of probe light, under the premise that the temperature in the heating region does not change and the Brillouin frequency shift (BFS) of the heating region is known. This method can realize the recognition of small length under the condition of wide pulse width. The theoretical analysis shows that the different lengths of the heating region will lead to different gains when the spatial resolution corresponding to the pulse width of the pulsed light is larger than the length of the heating region. And through theoretical derivation and simulation, it is concluded that the relationship between the intensity of probe light and the length of the heating region satisfies the exponential growth. Further experiments verify that the exponential growth is approximately linear in the range of small length changes. The length of the heating region can be inversely deduced by using the linear relationship by detecting the intensity of probe light. When the length of sensing fiber is 100 m and the heating region changes from 2 cm to 8 cm, 1 cm heating region changes can be identified.

Thermal Neutron Measurement Capability of a Single Crystal CVD Diamond Detector near the Reactor Core Region of UTR-KINKI

Thermal neutron flux evaluation using a single crystal diamond detector (SDD) was carried out in the core region of the UTR-KINKI reactor where a mixed radiation field by thermal and fast neutrons and gamma-ray exists. The pulse shape discrimination method to extract pulses with a rectangular shape as well as a wide pulse-width was established to exclude pulses induced by gamma-rays. The SDD, using a 6LiF thermal neutron converter, is able to detect pulse events caused not only by fast neutrons but also by thermal neutrons through energy depositions into the diamond by energetic alpha and triton particles induced by thermal neutrons. Additionally, the SDD without the thermal neutron converter was used for the measurement of the energy deposition events only by fast neutrons. A comparison of the pulse counts of the SDD with or without the thermal neutron convertor deduced the energy deposition spectra by thermal neutrons. The thermal neutron flux in the core region of the UTR-KINKI reactor was evaluated to be 7.6×106 n cm−2 s−1 W−1 up to a reactor power of 1 W.

Stimulation of the dorsal root ganglion using an Injectrode®

Objective. The goal of this work was to compare afferent fiber recruitment by dorsal root ganglion (DRG) stimulation using an injectable polymer electrode (Injectrode®) and a more traditional cylindrical metal electrode. Approach. We exposed the L6 and L7 DRG in four cats via a partial laminectomy or burr hole. We stimulated the DRG using an Injectrode or a stainless steel (SS) electrode using biphasic pulses at three different pulse widths (80, 150, 300 μs) and pulse amplitudes spanning the range used for clinical DRG stimulation. We recorded antidromic evoked compound action potentials (ECAPs) in the sciatic, tibial, and common peroneal nerves using nerve cuffs. We calculated the conduction velocity of the ECAPs and determined the charge-thresholds and recruitment rates for ECAPs from Aα, Aβ, and Aδ fibers. We also performed electrochemical impedance spectroscopy measurements for both electrode types. Main results. The ECAP thresholds for the Injectrode did not differ from the SS electrode across all primary afferents (Aα, Aβ, Aδ) and pulse widths; charge-thresholds increased with wider pulse widths. Thresholds for generating ECAPs from Aβ fibers were 100.0 ± 32.3 nC using the SS electrode, and 90.9 ± 42.9 nC using the Injectrode. The ECAP thresholds from the Injectrode were consistent over several hours of stimulation. The rate of recruitment was similar between the Injectrodes and SS electrode and decreased with wider pulse widths. Significance. The Injectrode can effectively excite primary afferents when used for DRG stimulation within the range of parameters used for clinical DRG stimulation. The Injectrode can be implanted through minimally invasive techniques while achieving similar neural activation to conventional electrodes, making it an excellent candidate for future DRG stimulation and neuroprosthetic applications.

4.08 mJ, 0.976 μs Er: YAG ring laser oscillator

Er:YAG ring laser with high-energy and wide pulse duration, which is resonantly pumped by a fiber laser at 1532 nm, is reported in this paper. Maximum power 2.62 W was implemented from ring resonator at 1645 nm. By transforming pulse repetition frequency (PRF), pulsed output energy was 4.08 mJ under 100 Hz PRF with a pulse width of 0.976 μs under the Q-switching regime. Since the wind measurement accuracy of coherent wind lidar is determined by the pulse width of the emission laser, this 1.6 µm single-frequency laser with high energy and wide pulse width is an ideal laser source for coherent wind lidar.

Fast radio burst detection in the presence of coloured noise

ABSTRACT In this paper, we investigate the impact of correlated noise on fast radio burst (FRB) searching. We found that (1) the correlated noise significantly increases the false alarm probability; (2) the signal-to-noise ratios (S/N) of the false positives become higher; (3) the correlated noise also affects the pulse width distribution of false positives, and there will be more false positives with wider pulse width. We use 55-h observation for M82 galaxy carried out at Nanshan 26m radio telescope to demonstrate the application of the correlated noise modelling. The number of candidates and parameter distribution of the false positives can be reproduced with the modelling of correlated noise. We will also discuss a low S/N candidate detected in the observation, for which we demonstrate the method to evaluate the false alarm probability in the presence of correlated noise. Possible origins of the candidate are discussed, where two possible pictures, an M82-harboured giant pulse and a cosmological FRB, are both compatible with the observation.

Involuntary sustained firing of plantar flexor motor neurones: effect of electrical stimulation parameters during tendon vibration

PurposeSimultaneous application of tendon vibration and neuromuscular electrical stimulation (NMES) induces an involuntary sustained torque. We examined the effect of different NMES parameters (intensity, pattern of stimulation and pulse width) on the magnitude of the evoked involuntary torque.MethodsPlantar flexor torque was recorded during 33-s Achilles tendon vibration with simultaneous 20-Hz NMES bouts on triceps surae (n = 20; 13 women). Intensity was set to elicit 10, 20 or 30% of maximal voluntary contraction torque (MVC), pulse width was narrow (0.2 ms) or wide (1 ms), and the stimulus pattern varied (5 × 2-s or 10 × 1-s). Up to 12 different trials were performed in a randomized order, and then repeated in those who produced a sustained involuntary torque after the cessation of vibration.ResultsSix of 7 men and 5 of 13 women produced a post-vibration sustained torque. Eight of 20 participants did not complete the 30% trials, as they were perceived as painful. Torque during vibration at the end of NMES and the increase in torque throughout the trial were significantly higher in 20 than 10% trials (n = 11; 9.7 ± 9.0 vs 7.1 ± 6.1% MVC and 4.3 ± 4.5 vs 3.6 ± 3.5% MVC, respectively). Post-vibration sustained torque was higher in wide pulse-width trials (5.4 ± 5.9 vs 4.1 ± 4.3% MVC). Measures of involuntary torque were not different between 20 and 30% trials (n = 8).ConclusionBouts of 5 × 2-s NMES with wide pulse width eliciting 20% MVC provides the most robust responses and could be used to maximise the production of involuntary torque in triceps surae.

Modular solid‐state pulse generator based on multi‐turn LTD

A modular solid-state pulse generator based on a multi-turn linear transformer driver (LTD) is designed for the application of pulse power techniques with a high voltage, large current and wide pulse width. The LTD adopts the method of multi-turn winding on the magnetic core, which can help to output pulses of wide width. The isolation of the power supply with windings in the same direction of the LTD modules is designed, and the isolation voltage of the magnetic cores is the working voltage of the LTD modules. A modular solid-state pulse generator based on the multi-turn LTD is developed, which is composed of 10 LTD modules. Each module consists of 18 energy storage capacitors, metal-oxide-semiconductor field-effect transistors and their driving circuits connected in parallel. The pulse generator can output pulses with parameters including a voltage ranging from 0 to 5000 V, a pulse current up to −500 A, and a pulse width ranging from 200 ns to 5 μs. When all modules work in synchronisation, rectangular pulses can be produced with a rise time of 30 ns and a fall time of 16 ns. If all modules are asynchronised, trapezoidal pulses are produced with adjustable step-like rising and falling edges. Moreover, a higher-voltage pulse can be achieved by increasing the number of LTD modules.

A Digital Controlled Pulse Generator for a Possible Tumor Therapy Combining Irreversible Electroporation With Nanosecond Pulse Stimulation.

The irreversible electroporation with microsecond electric pulses is a new ablation technique adopted in the tumor therapy worldwide. On the other hand, the nsPEF (nanosecond pulsed electric field) has been proved to provide a means to induce immunogenic cell death and elicits antitumor immunity, which is under intensive in-vitro and in-vivo studies and in clinical trials. Normally, one needs two different types of electric pulse generators for producing the pulses in the ranges of nanosecond and microsecond, respectively. In order to realize these two types of tumor treatments in complementary and optimize electrical pulse parameters, we have developed a compact high-voltage pulse generator with a wide pulse width tuning range, based on a capacitor discharging configuration digitally controlled by a silicon carbide MOSFET switching array through a pair of optic-coupler drivers. The developed digital pulse generator is capable of adjusting: pulse width over 100-100μs, voltage over 0-2kV and repetition rate up to 1.2 kHz. The pulse generator is designed in simulation, implemented and verified in experiments. The pulse generator is shown to deliver a complementary treatment on Murine melanoma B16 cell lines, i.e., triggering the cell early apoptosis under the 300ns pulse stimulation while a complete killing under the 100ns pulses. The pulse generator is further demonstrated to induce antitumor immunity in a preliminary in vivo study on the mice model.

Improvement of processing quality based on VHF resonant micro-EDM pulse generator

As an important non-traditional machining technology, micro-electrical discharge machining (micro-EDM) has become one of the ideal methods for conducting material parts in the mesoscopic scale. However, the current micro-EDM pulse generator has low discharge frequency and wide pulse width, and its nano-scale high-efficiency erosion ability is still difficult to meet the increasing practical requirement. For this purpose, a micro-energy pulse source with narrow pulse width and high-voltage amplitude, which is different from the current typical micro-energy pulse generator, is designed for a pulse generator with more fine-etching ability. Using the principle of circuit resonance, the very high-frequency (VHF) resonant discharge pulse generator can produce an open-circuit voltage waveform with a discharge frequency of 90 MHz and a peak value of 70 V. The single-pulse discharge energy can be continuously processed as low as 6nJ. Based on the VHF pulse generator and the transistor-type pulse generator, the discharge erosion experiments are carried out, and the surface roughness and recast layer are analyzed and compared. The experimental results show that the former processing quality is obviously better than the latter. The surface roughness after processing at a discharge frequency of 90 MHz can reach Ra 42 nm, the average diameter of craters is 0.38 μm, and the hole edge processed at a discharge frequency of 55 MHz has almost no recast layer which achieves similar cold processing effects.

Generation processes of superfluorescence of biexcitons in CuCl quantum dots by one- and two-photon resonant excitation

We investigated the influence of excitation processes of a biexciton on the generation of superfluorescence, which is pulsed radiation from coherently coupled two-level systems, from biexcitons in CuCl quantum dots. Two excitation processes of biexcitons were examined: resonant two-photon excitation of biexcitons, and resonant one-photon excitation of excitons. The excitation density dependence of the time-resolved photoluminescence was measured. The results showed that for one-photon excitation, a stronger peak intensity, longer delay time and wider pulse width were observed compared to resonant two-photon excitation. The high density of the excited dots in the one-photon excitation process results in the strong pulse, while an initial population of excitons results in a suppression of coherent coupling.

A New Geosynchronous SAR Constellation and its Signal Characteristics

The Geosynchronous Synthetic Aperture Radar (GEO SAR) has a long synthetic aperture time. The temporal decoherence and azimuth variance characteristics of echo are significant, that brings great challenges to signal to process. In order to reduce the synthetic aperture time and thus improve the observation flexibility and efficiency, this paper proposes a SAR system mounted on a special satellite in reverse equatorial geosynchronous orbit, so-called the reverse equatorial GEO SAR. The orbit is nearly circular and the orbital plane coincides with the equatorial plane. The satellite flies against the direction of the Earth's rotation. The relative velocity is accelerated twice and the synthetic aperture time is shorter. The satellite does not drift in latitude direction and drifts uniformly in longitude direction. The echo has azimuth invariance property. Meanwhile, the 24-hour continuous observation can be achieved for areas with a certain range of latitude by means of large squint technique and constellation design. As the GEO SAR has high orbit, large delay, large squint angle, and wide pulse width, the complex modulation effects are generated by continuous motion between the satellite and target during the imaging period. In this paper, the uniform acceleration curve motion is used to describe the motion of both satellite and target, and the linear approximation is used to describe the slant range change in the process of transmitting and receiving one pulse. Accordingly, an accurate signal model for the reverse equatorial GEO SAR is established, which provides a theoretical model for signal characteristics analysis and imaging algorithms development.

Achieving high gating performance for ion mobility spectrometry by manipulating ion swarm spatiotemporal behaviors in the vicinity of ion shutter

Ion shutter is one of the key components of the drift-tube types of ion mobility spectrometer, which affects both the resolving power and sensitivity of an ion mobility spectrometer. In this work, a spatiotemporal model was built to understand the behaviors of the ion swarms around the ion shutter. For simplicity, a Tyndall-Powell gate (TPG) was chosen as the gating disturbance to the field on the two sides of ion shutter could be separated. It can be inferred from the spatiotemporal model that the ion swarm could be diluted in front of the TPG when the gate closing voltage (GCV) was superposed on the grid facing the ionization region, while it could be compressed behind the TPG when the GCV was superposed on the other grid. These inferences conformed to the narrower and higher ion peaks obtained at GCV superposed on the latter grid and were further verified by the ion distribution profiles obtained at a wide gate opening pulse width. Finally, the product of the resolving power and the gating efficiency was proposed to evaluate the gating performance of an ion shutter. At GCV superposed on the grid facing the drift region, the best gating performance of 42 was obtained with peak height of 1.63 nA and resolving power of 57.2, and was almost twice as high as the optimal gating performance at GCV superposed on the other grid.

Incorporating MoS2 saturable absorption with nonlinear polarization rotation for stabilized mode-locking fibre lasers

Stabilized hybrid mode-locking of erbium-doped fiber laser (EDFL) by incorporating strong MoS2 saturable absorber and weak nonlinear polarization rotation (NPR) is demonstrated. At threshold condition, the MoS2 starts the mode-locking of EDFL to provide a 680 fs wide pulsewidth with a time-bandwidth product of 0.407. With only the unintentionally weak NPR effect, the fluctuated EDFL pulsewidth ranged between 377 and 382 fs is observed with a tolerant half-wave-plate orientation angle of θHWP =21°. Adding MoS2 enhances the self-amplitude modulation (SAM) and shortens a pulsewidth to 305–330 fs with an allowable θHWP increasing up to 76°, implying the enhanced stabilization of passively mode-locking in EDFL. Enduing the weak NPR with strong saturable absorption (SA) effect significantly makes up the maximal SAM coefficient from 4.02 × 10−4 to 1 × 10−3, whereas the self-phase modulation (SPM) coefficient remains unaltered as that without adding the MoS2. The MoS2 saturable absorber additively offsets SAM beyond its threshold to enlarge the polarization tolerance without altering the SPM. Adjusting the polarization controller with unintentional polarization dependence affects the NPR induced polarization dependent loss so as to strengthen the SAM for mandatory mode-locking optimization of EDFL.

Phrenic afferent stimulation modulates cardiorespiratory output in the adult rat

Anatomical work from our laboratory indicates that small and large diameter phrenic nerve afferent fibers localize to the dorsal laminae, project throughout the ipsilateral spinal gray matter and occasionally reach the contralateral dorsal horn. In ongoing experiments, we are testing the hypothesis that activation of phrenic afferent neurons modulates contralateral phrenic motor output and arterial blood pressure in the adult rat. In anesthetized and ventilated adult Sprague‐Dawley rats, one phrenic nerve was electrically stimulated using a bipolar electrode, while respiratory bursting in the contralateral phrenic nerve and arterial blood pressure were recorded. Inspiratory triggered phrenic nerve stimulation was delivered for 20 seconds (approximately 18 breaths) at 40pps using a narrow (0.1 ms) pulse width to target activation of large diameter myelinated axons, or a wide (1.0 ms) pulse width to recruit small diameter myelinated and unmyelinated afferents. The experimental protocol consisted of eight currents (10, 25, 50, 70, 90, 120, 160, 220μA) delivered in a random order, each separated by a 5 minute recovery period (i.e. no stimulation). Each stimulus current caused a progressive increase in contralateral phrenic amplitude during the stimulation period. Phrenic amplitude remained above baseline for at least 1 minute after the cessation of stimulation. At lower currents (<50μA), the wide pulse stimulation was more effective at increasing contralateral phrenic output compared to the narrow pulse stimulation, while higher currents (>50μA) elicited a similar increase in contralateral amplitude regardless of pulse width. In addition, phrenic nerve stimulation was associated with a brief decrease, followed by an increase in mean arterial blood pressure during stimulation. In separate rats, a unilateral dorsal root rhizotomy (C3, C4, C5) was performed prior to phrenic nerve stimulation to eliminate afferent input to the spinal cord. This treatment prevented both the increase in contralateral phrenic amplitude and blood pressure at all currents and both pulse widths, indicating that the observed responses are due to activation of phrenic afferents. These preliminary results confirm that activation of phrenic afferents can modulate the activity of the contralateral phrenic motor pool, and suggest that phrenic afferents are capable of initiating phrenic motor plasticity.Support or Funding Information1F32NS095620‐01 (KS), T32‐ND043730 (MS), SPARC OT2 OD023854 (DDF), 1 R01 NS080180‐01A1 (DDF)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Influence investigation on ranging performance for range-gated Geiger-mode avalanche photodiode ladar.

The ranging performance for Geiger-mode avalanche photodiode (Gm-APD) laser detection and ranging (ladar) is mainly evaluated by range accuracy and precision; although Gm-APD ladar can evaluate the ranging performance of the exact position, it is not helpful to comprehensively evaluate the influence on the ranging of each parameter in the whole gate. Due to the target echo's stochastic trigger making the delay adjustment inaccurate, the position of the echo in the gate is stochastic in the actual detection process, so the theoretical calculation may not be able to make ladar ranging performance clear. As to this question, based on the central limit theorem, and assuming the position of the target in the gate obeys Gaussian distribution, while also combining the Gm-APD triggering probability model, we propose the mean ranging accuracy and precision theory to objectively evaluate the ranging performance. At the same time, we combine the theory with the ladar ranging equation to investigate the effect of parameters such as laser transmitting energy, pulse width, gate width, target range, and noise intensity on ranging performance. The results show high transmitting energy, narrow gate width, short target range, and low noise intensity make mean ranging accuracy and precision low. The narrow pulse width will result in lower mean ranging accuracy and high mean ranging precision. Wide pulse width has the opposite effect; through comprehensive comparison, 10∼30 ns pulse width is more reasonable. According to theoretical analysis results, to achieve ladar's high ranging performance, we put forward concrete measures for improvement-reducing the gate width, enhancing laser energy, using a narrowband filter to reduce false alarm of noise, etc., consequently the research in this paper has significance for the Gm-APD ladar experimental parameter selection.

Effect of tendon vibration during wide-pulse neuromuscular electrical stimulation (NMES) on muscle force production in people with spinal cord injury (SCI)

BackgroundNeuromuscular electrical stimulation (NMES) is commonly used in skeletal muscles in people with spinal cord injury (SCI) with the aim of increasing muscle recruitment and thus muscle force production. NMES has been conventionally used in clinical practice as functional electrical stimulation (FES), using low levels of evoked force that cannot optimally stimulate muscular strength and mass improvements, and thus trigger musculoskeletal changes in paralysed muscles. The use of high intensity intermittent NMES training using wide-pulse width and moderate-intensity as a strength training tool could be a promising method to increase muscle force production in people with SCI. However, this type of protocol has not been clinically adopted because it may generate rapid muscle fatigue and thus prevent the performance of repeated high-intensity muscular contractions in paralysed muscles. Moreover, superimposing patellar tendon vibration onto the wide-pulse width NMES has been shown to elicit further increases in impulse or, at least, reduce the rate of fatigue in repeated contractions in able-bodied populations, but there is a lack of evidence to support this argument in people with SCI.MethodsNine people with SCI received two NMES protocols with and without superimposing patellar tendon vibration on different days (i.e. STIM and STIM+vib), which consisted of repeated 30 Hz trains of 58 wide-pulse width (1000 μs) symmetric biphasic pulses (0.033-s inter-pulse interval; 2 s stimulation train; 2-s inter-train interval) being delivered to the dominant quadriceps femoris. Starting torque was 20% of maximal doublet-twitch torque and stimulations continued until torque declined to 50% of the starting torque. Total knee extensor impulse was calculated as the primary outcome variable.ResultsTotal knee extensor impulse increased in four subjects when patellar tendon vibration was imposed (59.2 ± 15.8%) but decreased in five subjects (− 31.3 ± 25.7%). However, there were no statistically significant differences between these sub-groups or between conditions when the data were pooled.ConclusionsBased on the present results there is insufficient evidence to conclude that patellar tendon vibration provides a clear benefit to muscle force production or delays muscle fatigue during wide-pulse width, moderate-intensity NMES in people with SCI.Trial registrationACTRN12618000022268. Date: 11/01/2018. Retrospectively registered.

Experimental demonstration of improving resonant-multipactor threshold by three-dimensional wavy surface

A proof-of-principle experiment is presented demonstrating the suppression of multipactor breakdown in a coaxial multipactor device with three-dimensional periodic wavy surfaces. By changing the power and pulse width of the microwave source, threshold behavior near breakdown was obtained for this wavy-surface structure and a smooth-surface structure used for comparison. With a wide pulse width at a suitable power, the coefficient of reflection for the smooth-surface structure was found to increase, whereas the coefficient of transmission decreased. For the wavy-surface structure, a similar behavior appeared, only when the microwave pulse had a width of order of a few seconds. Accompanied by changes in transmission power characteristics, distinct increases in the second and third harmonic components were evident for the smooth-surface structure. These experimental results demonstrate that the wavy-surface structure effectively suppresses multipactor breakdown with the suppression increasing with the pulse width.