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A new visible imaging system characterizing a flexible optical design and delivering high resolution frames is established on the HL-2A tokamak. It features a modular configuration, consisting of a front-end imaging lens, a set of bilateral telecentric relay lenses, and a camera. To avoid the effects of plasma radiation (x and gamma-rays) and magnetic field variation on the camera, it should be away from the coils. Therefore, the length of the relay lenses determines the total size of the imaging system. The main feature of this imaging system is to realize the variation of field of view (FOV) by interchanging the front-end prime lenses or by using a zoom lens directly rather than designing the optical system afresh, which lowers the cost drastically. The primary purpose of varying FOV is to enrich the versatility of this system, i.e., focusing on a narrow FOV such as gas puff imaging or a wide FOV such as the plasma cross sections. During the HL-2A experiments, this visible imaging system is used to provide high quality pictures of the plasma–wall interaction, divertor detachment, pellet injections, and so on. The frames confirmed that a strong radiation close to the X point is correlated with the completely detached inner target.

Pyoderma gangrenosum (PG) is a rare neutrophilic dermatosis, closely associated with the immune system. Its pathogenesis is currently not clear. The lack of specificity in the clinical manifestations and histopathological changes of PG leads to a long clinical diagnosis cycle and even misdiagnosis, which is easy to delay treatment or promote the deterioration of ulcer wound. The diagnosis of this disease is still very difficult, which poses a great challenge to wound repair practitioners. This article reviews the research advances on the pathophysiology, clinical features, and diagnosis of PG in recent years, with the aim of providing reference for relevant clinical practitioners.坏疽性脓皮病（PG）是一种罕见的嗜中性皮肤病，与免疫系统密切相关，其发病机制目前并不明确。PG的临床表现及组织病理学变化缺乏特异性，导致其临床诊断周期较长甚至可能被误诊，容易因此延误治疗或促使溃疡创面恶化。目前该病的诊断仍十分困难，给创面修复医师带来了极大的挑战。该文综述了近年来有关PG的病理生理、临床特征、诊断等方面的研究进展，以期为相关临床工作者提供参考。.

During the last several years, the HL-2A experiment has made significant progress in the following areas: (1) lower-hybrid wave (LHW) heating and current drive, (2) plasma confinement and turbulent transport, (3) magnetohydrodynamic (MHD) instabilities and energetic particle physics and (4) H-mode and edge localized mode (ELM) control. The results show that the LHW system working in the co-current mode can reach higher driving efficiency and full non-inductive lower-hybrid current drive (LHCD) has been achieved. The intrinsic poloidal torque characterized by the divergence of the residual stress is deduced from synthesis for the first time. The dynamics of spectral symmetry breaking in drift wave turbulence is in good agreement with the development of the poloidal torque to drive the edge poloidal flow. The influence of the cross-phase dynamics on turbulent stress was also investigated. The ion internal transport barrier has been observed in the NBI-heated plasma, and inside the barrier the ion thermal transport is reduced to the neoclassical level. Besides, micro-turbulence is modulated by the rotation frequency of the magnetic island, and this modulation effect is related to a critical island width. Strong E × B shear is found at the island boundary. Three kinds of axisymmetric modes, beta-induced Alfven eigenmode (BAE), toroidal Alfven eigenmode (TAE) and the ellipticity-induced Alfven eigenmode (EAE), are found to be driven unstable by nonlinear mode coupling between Alfven eigenmodes and tearing mode which is well explained by the nonlinear gyrokinetic theory. The fishbone and tearing modes were actively controlled by the electron cyclotron resonance heating (ECRH). The dynamics of the edge plasma flows and turbulence during the L–I–H transition have been dedicatedly investigated. The geodesic acoustic mode (GAM) and limit cycle oscillation (LCO) coexist for a short time and disappear in the H-mode plasma with the increasing of E × B shear flow before the I–H transition, which plays an important role in the turbulence suppression. Different techniques, such as LHW, ECRH, resonant magnetic perturbation (RMP), and impurity seeding by the laser blow-off (LBO) and supersonic molecular beam injection (SMBI), have been successfully applied to control the large ELMs. It has been found that pedestal turbulence enhancement might be responsible for the observed mitigation effect.

$Z_{\mathrm {eff}}$ is measured by two visible bremsstrahlung diagnostics on HL-2A tokamak, one of which uses a high spectral resolution spectrometer coupled with an electron multiplied CCD (temporal resolution of 100 Hz), and the other uses a filterscope system (temporal resolution of 1 MHz). The bremsstrahlung brightness measured by them coincides with each other very well. $\bar {Z}_{\mathbf {eff}}$ is systematically measured under different discharge conditions, such as divertor and limiter configurations, ohmic and auxiliary heating phases, before and after siliconization, and $L$ – $H$ transition. Under ohmic phase, $\bar {Z}_{\mathbf {eff}}$ is higher in the limiter configuration than that in the divertor configuration by a factor of ~1.5 under high-density regime. $\bar {Z}_{\mathbf {eff}}$ increases in all cases of auxiliary heating scenarios due to enhanced plasma–wall interaction, accompanied by influx increases of low ionization states of impurities such as C2+ and Fe1+ in plasma edge. Siliconization for wall conditioning is prominently effective in lowering the main impurity influxes in plasma edge and thus the impurity level, and a concentration of ~4% for carbon and ~0.2% for iron is roughly evaluated for a typical nonsiliconized plasma. A simple relationship that $Z_{\mathrm {eff}}$ is positively correlated with $\Phi _{\mathrm {in}}$ and $\tau _{\mathrm {p}}$ is verified from the L - and $H$ -mode features, where $\Phi _{\mathrm {in}}$ is the impurity influx and $\tau _{\mathrm {p}}$ the particle confinement time. A nearly constant $\bar {Z}_{\mathbf {eff}}$ evolution is observed during $L$ – $H$ and $H$ – $L$ transition and it seems that $\bar {Z}_{\mathbf {eff}}$ is insensitive to $L$ – $H$ and $H$ – $L$ transition under some $Z_{\mathrm {eff}}$ (0) threshold. The $Z_{\mathrm {eff}}$ profiles are flat/weakly hollow in plasma core region (rho $Z_{\mathrm {eff}}$ (0) and tend to be peaked when $Z_{\mathrm {eff}}$ (0) is larger than 3, which agrees with the neoclassical theory prediction.

Double-peaked distribution (DPD) of particle flux has only been observed on the outer divertor target in electron cyclotron resonance heating deuterium plasmas with [Formula: see text] toward the X-point in the HL-2A tokamak using high spatiotemporal Langmuir probe arrays. The experimental results demonstrate that the formation of the DPD is mainly due to the enhanced poloidal [Formula: see text] drift flow stimulated in the divertor region, which is dependent on the plasma density, heating power, and divertor structure. The experimental results are qualitatively consistent with the SOLPS simulation. The experiment also shows that the formation of the DPD might be related to the enhanced cross field transport in the far scrape-off layer. This experimental findings presented here reveal the crucial role played by the synergistic effect of poloidal E × B drift flow and the closed divertor structure in the redistribution of the particle flux, which provides a potential way for the control of high heat flux in future fusion devices.

Fast static reanalysis techniques are very important tools often used in structural optimization design. Generally, the existing exact methods for static reanalysis are only suitable for low-rank m...

In order to reconstruct the plasma current density, the Current Profile Fitting (CPF) code has been successfully developed on the HL-2A tokamak. A seven-channel motional Stark effect (MSE) ...

Fused deposition modeling (FDM) in 3D printing is a very promising technology and one of the focuses of scientific research. The main reason is that it has the advantages of simple structure, relatively low price and convenient operation, which has made its development more and more rapid in recent years. However, due to the fact that the FDM products are susceptible to the operating environment, the printing quality is not stable enough and the development is restricted. In addition, this research uses Taguchi method to explore FDM to optimize a long and thin desired volume of the workpiece under different printing parameters (printing temperature, printing speed ratio, and printing layer thickness). From the experimental results, the size of the factors that affect the FDM’s expected volume of the workpiece is, in order, the printing temperature is the most important, the printing speed ratio is the second, and the printing layer thickness is the smallest. The optimal parameter combination for the desired workpiece volume is A1B1C1, that is, the printing temperature is 190°C, the printing speed ratio is 0.286 (20 mm/s on the outer side, 70 mm/s on the inner side), and the printing layer thickness is 0.1 mm. Finally confirmed the experimental results and found that the volume error of the finished product using the best printing parameters is less than 0.3 %, which proves that the optimized printing parameters obtained by Taguchi method are indeed effective and feasible.

The wide-angle view imaging system, in terms of a tangential view diagnostic with field of view (FOV) of 56.8° and a downward-looking diagnostic from the top of the machine with FOV of 94.7°, has been newly constructed for the first plasma of the HL-2M tokamak achieved in December 2020. Its mission in this stage is to monitor the plasma evolution during its startup, sustainment, and disruption in the visible spectral range as well as the plasma–wall interaction. For the latter ultrawide view diagnostic, nearly three-quarters of the divertor region and half the area of the inner wall are in the view range. Both the diagnostics are characterized by a similar optical structure, i.e., the light emission from the plasma is collected by a front-end lens and transferred through an imaging fiber bundle to the camera. This optical structure is suitable for application in the complex tokamak environment mainly because the fiber bundle is flexible. Photos of glow discharges are acquired prior to the first plasma for testing the FOVs in the vacuum vessel. The spatial resolution is ∼ 4 m m for the tangential view diagnostic and ∼ 10 m m for the downward-looking diagnostic. The temporal resolutions, ranging from 90 to 360 Hz by changing the region of interest or binning acquisition mode of the color camera, are applied to record the plasma evolutions and/or dust creation events during the first plasma campaign.

A Fast Charge eXchange Recombination Spectroscopy (CXRS) diagnostic with eight radial channels has been implemented on a HuanLiu-2A (HL-2A) tokamak with a time resolution of up to 10 kHz monitoring helium II spectra or 1 kHz monitoring carbon VI spectra. The crucial aspects of the fast CXRS are to improve the spectral intensity and the acquisition frequency. The spectral intensity has been greatly enhanced by customized fiber bundles. The main boost in optimizing the acquisition frequency is achieved by binning more pixel rows of the charge coupled device (CCD) representing one radial channel and by reducing the effective image area of the CCD. Consequently, the sawtooth oscillations of ion temperature and rotation velocity are continuously observed for the first time in the HL-2A tokamak.

Selecting stably expressed reference genes is crucial for evaluating real-time quantitative polymerase chain reaction (RT-qPCR) data via the relative quantification method. In the present-day study, our aim was to select optimal reference genes (RGs) for the investigation of target gene (TG) expression profiling in cancerous human laryngeal and hypopharyngeal tissues.12 cancerous laryngeal tissues and 10 cancerous hypopharyngeal tissues were investigated. The expression characteristics of 11 reference genes (18S rRNA, GAPDH, B2M, ACTB, TBP, ALAS1, RPL29, HMBS, HPRT1, GUSB, and PUM1), which were commonly used in RT-qPCR for the analysis of gene expression, were investigated using the geNorm, NormFinder, and BestKeeper algorithm programs.HMBS, ALAS1, and B2M were suggested as optimal RGs for studying human laryngeal and hypopharyngeal cancerous tissues together, laryngeal cancerous tissue by itself, and hypopharyngeal cancerous tissue by itself, respectively. If 2 or more reference genes are needed to achieve better standardization, 3 reference genes can optimally be used in combination to improve the accuracy of relative quantitation normalization. The recommended combinations for studying human laryngeal and hypopharyngeal cancerous tissues together, laryngeal cancerous tissue by itself, and hypopharyngeal cancerous tissue by itself were HMBS + HPRT1 + GUSB, ALAS1 + GUSB + HMBS, and B2M + HPRT1 + TBP, respectively.The recommended reference genes could be used to improve the accuracy of gene expression studies on the molecular mechanisms of cancerous human laryngeal and hypopharyngeal tissues. The selected combination of reference genes can effectively improve the accuracy of the relative quantitative diagnosis of gene expression levels, such as messenger RNA, circular RNA, and long-noncoding RNA.

Remote control of the diagnostic systems is the basic requirement for the high performance plasma operation in a fusion device. This work presents the development of the remote control system for the multichannel Doppler backward scattering (DBS) reflectometers. It includes a remote controlled quasi-optical system and a remote intermediate frequency (IF) amplifier gain control system. The quasi-optical system contains a rotational polarizer, its polarization angle is tunable through a remote controlled motor, and it could combine the microwave beams with a wide frequency range into one focused beam. The remote IF gain control system utilizes the digital microcontroller (MCU) technique to regulate the signal amplitude for each signal channel. The gain parameters of amplifiers are adjustable, and the feedback of working status in the IF system will be sent to MCU in real time for safe operation. The gain parameters could be controlled either by the Ethernet remote way or directly through the local control interface on the system. Preliminary experimental results show the effectiveness of the remote controlled multichannel DBS system.

A new hard X-ray (HXR) camera system has been planned to be developed for HL-2A tokamak (R0 = 1.65 m, a = 0.4 m, Bt = 2.8 T, and Ip = 0.5 MA), which is dedicated to the tomography of fast electron bremsstrahlung emission in the energy range 10 to 200 keV. The camera system includes two independent HXR cameras, which are both located in the same poloidal plane. Each camera is made up of 30 detection chords and views the whole poloidal cross section of the plasma. The spatial and temporal resolutions of the camera are 2 to 3 cm and 1 to 2 ms, respectively. HXR detection is performed using cadmium telluride (CdTe) semiconductors. Both simulation and experimental results suggest that an Al foil with a 0.3-mm thickness is the best candidate for filtering the low-energy X-ray photons. Powerful inversion techniques are employed to obtain the local HXR profiles as functions of time and photon energy. The HXR camera system planned for HL-2A tokamak is presented in detail.

Physics related to fast electrons in lower hybrid (LH) current drive (LHCD) plasma is a very important issue, since these particles will play an important role in runaway electron (RE) generation and lower hybrid wave (LHW)-related physics. Utilizing a new hard X-ray (HXR) pinhole camera, recent HL-2A tokamak experiments have devoted to enhancing the understanding of the physics on fast electrons and LHW. The fast electron bremsstrahlung (FEB) emission in the HXR energy range between 20 and 200 keV was measured by the HXR camera. To study the conversion of LHW-produced fast electrons into REs, a very short pulse of LHW, so-called “blip”, with duration of 5 ms was injected into the plasma during the current flattop phase. A strong enhancement of REs was induced by the blip injection. Measurements from the HXR camera show that the fast electrons generated by LHWs is mainly concentrated in 40-60 keV, which is well consistent with the calculated value based on Landau damping theory. The energy of these seed electrons is higher than the critical runaway energy. This phenomenon may be come from the synergetic effects of Dreicer and avalanche RE generation. Moreover, the measurements indicate that the spatial distribution of the fast electrons during LHCD has a peaked profile, implying that the fast electrons are mainly produced in the plasma core. It also suggests that the energy of the LHW mainly deposited in the plasma core region.

A modified variational iteration method (MVIM) is proposed for nonlinear oscillators. Different from the existing VIM, the algebraic equation deduced at each iteration stage is always linear when the proposed approach is applied to conservative oscillators. Therefore, highly accurate approximations can be easily obtained. The Duffing and the van der Pol equations are presented to validate the MVIM. Numerical examples show that the presented method is valid for both weakly and strongly nonlinear oscillators. In addition, it reveals that the MVIM is equivalent to a modified Mickens iteration scheme. Furthermore, the MVIM is extended by means of an auxiliary parameter. This parameter provides us with a convenient way to control and adjust the convergence of VIM approximations when necessary.

Two silicon drift detectors combine with the new and nonconventional software pulse-height analyzer (SPHA) to measure the time evolution of soft-X-ray spectra, the thermal electron and superthermal...

A computationally attractive method is proposed in this study to provide an insight to the location and extent of structural damage. The proposed method makes use of the matrix disassembly technique and approaches the damage location and extent problem in a decoupled fashion. First, a scheme is developed to determine the damage location by calculating a damage localization vector, which is derived from the modal residual force criteria. With location determined, the corresponding damage extent can be easily obtained only by the processes of division. The algorithm is applied to a numerical example and its efficiency is demonstrated through damage simulations.

Structural damage identification using ambient vibration modes has become a very important research area in recent years. The main issue surrounding the use of ambient vibration modes is the mass normalization of the measured mode shapes. This paper presents a promising approach that extends the flexibility sensitivity technique to tackle the ambient vibration case. By introducing the mass normalization factors, manipulating the flexibility sensitivity equation, the unknown damage parameters and mass normalization factors can be computed simultaneously by the least-square technique. The effectiveness of the proposed method is illustrated using simulated data with measurement noise on three examples. It has been shown that the proposed procedure is simple to implement and may be useful for structural damage identification under ambient vibration case.

The use of changes in dynamically measured flexibility matrices to detect structural damage has received considerable attention during the last years. A new flexibility-based method is proposed in this study to provide an insight to the characterizations of structural damage. The presented method makes use of the eigenparameter decomposition of structural flexibility change and approaches the damage identification problem in a decoupled manner. First, a theory is developed to determine the number of damaged elements according to the number of non-zero eigenvalues of structural flexibility change. With the number of damaged elements determined, the localization and quantification algorithms are then developed. The proposed method is applied to three numerical examples and its efficiency is demonstrated through damage simulations. Copyright © 2008 John Wiley & Sons, Ltd.

A high-frequency magnetic probe system is designed, calibrated and constructed on the HL-2A tokamak. To investigate the factors which affect the probe frequency response, the inductance and capacitance in the probe system are analyzed using an equivalent circuit. Suitable sizes and turn number of the coil, and the length of transmission cable are optimized based on the theory and detailed test in the calibration. To deal with the frequency response limitation and bake-out, the ceramic grooved technique is used and the probe is wound with a bare copper wire. A cascade filter is manufactured with a suitable bandwidth as well as a good phase consistency between channels. The system has been used in the experiment to measure high frequency (≤300 kHz) magnetohydrodynamic fluctuations, which can meet the requirement of physical analysis on HL-2A.

The frequency modulated continuous wave reflectometer was developed for the first time on the HL-2A tokamak. The system utilizes a voltage controlled oscillator and an active multiplier for broadband coverage and detects as heterodyne mode. Three reflectometers have been installed and operated in extraordinary mode polarization on HL-2A to measure density profiles at low field side, covering the Q-band (33–50 GHz), V-band (50–75 GHz), and W-band (75–110 GHz). For density profile reconstruction from the phase shift of the probing wave, a corrected phase unwrapping method is introduced in this article. The effectiveness of the method is demonstrated. The density profile behavior of a fast plasma event is presented and it demonstrates the capability of the reflectometer. These diagnostics will be contributed to the routine density profile measurements and the plasma physics study on HL-2A.

A qualitative model which includes three loops of zonal flow vs. turbulence and turbulence vs. pressure gradient is proposed for the experimentally observed two types of limit cycle oscillations (LCOs) and low-intermediate-high (L-I-H) confinement transitions. The experimental evidences supporting the model and revealing the roles of turbulence– and pressure-gradient–induced flows in triggering the H-mode at marginal heating power in tokamak plasmas are presented. The dominant role played by pressure-gradient–induced flows in I-phase of type-J LCO as well as I-H transition is demonstrated, along with that done by the turbulent-Reynolds-stress–driven zonal flows in the L-I transition as well as I-phase of type-Y LCO. The trigger and conditions for the I-H transition are identified from the experimental observations.

The Choi-Williams distribution (CWD) technique is introduced as a time-frequency tool for processing data measured from the new developed homodyne and the fixed frequency reflectometry in the HL-2A tokamak. The comparison between spectrogram and CWD for the simulated signal is presented. It indicates that the CWD can greatly improve the representation of the time-frequency content of the multi-components signal. Its effectiveness is demonstrated through two applications in HL-2A, which are the extraction of beat frequencies from the frequency modulated-continuous wave reflectometry (FM-CW) and the characterizing of the fluctuations. The density profile inversed from the group delay of the FM-CW and the density fluctuations deduced from the fixed-frequency reflectometry would be more reliable and accurate by using the CWD technique.

The formation of a transient internal transport barrier (ITB) is observed after the electron-cyclotron-resonance-heating (ECRH) switch-off in the HL-2A plasmas, characterized by transient increase of central electron temperature. The newly developed correlation reflectometer provided direct measurements showing reduction of turbulence in the region of steepened gradients for the period of ITB formation triggered by the ECRH switch-off. Furthermore, the reduction of core turbulence is correlated in time with the appearance of a low-frequency mode with a spectrally broad poloidal structure that peaks near zero frequency in the core region. These structures have low poloidal mode number, high poloidal correlation, and short radial correlation and are strongly coupled with high-frequency ambient turbulence. Observation indicates that these structures play important roles in the reduction of the core turbulence and in improvements of the core transport after the off-axis ECRH is turned off.

The operation conditions have been improved via developing new technologies and improving the hardware on HL-2A tokamak in recent years. The ECRH system has been upgraded to 3 MW/68 GHz, the supersonic molecular beam injection (SMBI) fuelling technique has been developed further, and clusters can be formed in the SMB by cooling the gas to around liquid nitrogen temperature, so that deeper penetration can be achieved. Moreover, there are about 30 kinds of diagnostics developed on HL-2A to measure the plasma parameters. These diagnostic systems include magnetics, microwave reflectometry, charge exchange recombination spectroscopy, Thomson scattering, FIR interferometer. Some of them were specially designed for the physics experiments. For example, a novel design of Langmuir probes was developed to study the 3-D structure of zonal flows. With these hardware development and improvement, new experimental results have been achieved in the fields of turbulence, transport, MHD instabilities, and energetic particle dynamics. In particular, the edge localized mode (ELM)y H-mode has been achieved by combining the auxiliary heating of NBI and ECRH, SMBI is beneficial for the L-H transition and the H-mode operation on HL-2A, and suitable for studying particle transport and controlling the ELMs during H-mode discharges due to its deep and local injection features and good controllability. In addition, the 3-D spectral structures of the low-frequency zonal flow and quasi-mode, which were predicted by theory and simulation, have been observed simultaneously. The beta-induced Alfven eigenmodes (BAEs), excited by large magnetic islands (m-BAE) and by energetic electrons (e-BAE), are investigated, these phenomena are under further study.

Structural damage identification using ambient vibration modes has become a very important research area in recent years. The main issue surrounding the use of ambient vibration modes is the mass normalization of the measured mode shapes. This paper presents a promising approach that extends the flexibility sensitivity technique to tackle the ambient vibration case. By introducing the mass normalization factors, manipulating the flexibility sensitivity equation, the unknown damage parameters and mass normalization factors can be computed simultaneously by the least-square technique. The effectiveness of the proposed method is illustrated using simulated data with measurement noise on a steel truss structure. The results show the good efficiency and stability of the proposed method on the identification of damage on more than one element. It has been shown that the proposed procedure is simple to implement and may be useful for structural damage identification under ambient vibration case.

This paper presents a damage detection method for truss structures using incomplete measured modes. The underlying principle of the proposed technique is to add known masses to the physical structure, measure the natural frequencies of this mass-modified system, and then use this set of new data as well as the original test data to identify damages with the help of eigenvalue perturbation method. Regardless of whether the structure is unsymmetrical or symmetrical, the proposed method can precisely identify damages of truss structures only by changes of the first few natural frequencies. The method has the practical attraction of only requiring information about the changes in a few of the eigenvalues between the undamaged and damaged states. A plane truss structure is used as a numerical example to demonstrate the feasibility of the proposed scheme. Results show that the presented method can successfully detect both the location and extent of damage in the truss structure even if the noisy data inevitably make the damage detection more difficult.

Eight strains of infectious bronchitis virus (IBV) were isolated between 1986 and 1995 from broilers and layers at eight different farms in four provinces in China. The viruses were isolated from flocks which suffered from either respiratory disease or nephritis and the majority had not been vaccinated against IBV. Six strains were shown by monoclonal antibodies to differ from H120, Connecticut and Arkansas 99 strains of IBV and also to differ from each other. Four of these strains were serotyped; one (NRZ) was of the Massachusetts serotype, three (HV, NB-90 and TJ) shared a degree of antigenic similarity and were of a serotype that differed from Massachusetts and Connecticut. NB-90 was similar to both Gray and T strains whereas TJ shared some similarity with the T strain. Four strains, HV, NB-90, YY and TJ induced 33, 47, 60 and 90% mortality, respectively, in 3-week-old specific pathogen-free chickens. Clinical signs and post-mortem findings were identical to those induced by the nephropathogenic T strain. Chickens vaccinated with H120 strain, and then challenged with four highly pathogenic strains HV, NB-90, YY and TJ were not protected as determined by both virus isolation and mortality. The results show that highly pathogenic IBV strains which induce clinical nephritis occur frequently in poultry flocks in China. They also confirm field observations on the lack of protection by currently used IB vaccines of the Massachusetts serotype against challenge with these nephropathogenic strains.

To evaluate the roles of EGFR expression in laryngeal keratosis.The ABC immunohistochemical method was performed to investigate the expression of EGFR in 32 cases of laryngeal keratosis tissue.The EGFR indices in light, moderate and serious non-typical hyperplasia were 12.5%, 22.5% and 47.8% respectively. There were significant differences between heavy with light and middle non-typical hyperplasia (P0.05).The EGFR might play some role in the process of carcinogenesis of laryngeal keratosis, and be as an useful marker for the assessment of the behavior and prognosis in the laryngeal premalignant lesions keratosis.

Experimental observation and theoretical analysis are presented for the nonlinear mode couplings between shear Alfven wave and magnetic island. In the sub-Alfven frequency range, two kind axi-symmetry magnetic activities with n = 0 have been observed during NBI on HL-2A. One kind has been identified, and belongs to EGAM. Another kind is found for the first time, its frequency lies in the range of TAE frequency. The Fourier bicoherence analysis suggests these axi-symmetry modes are generated by the nonlinear mode coupling via the decay process between Alfven eigenmodes and low-frequency MHD modes. The experimental results indicate that the nonlinear mode coupling is one of mechanisms of the energy cascade in energetic-particle turbulence or Alfven turbulence.

Poloidal magnetic field is a very important physical parameter for the understanding of heating and confinement in tokamak plasmas. One channel of an eight-chord, horizontally-viewing, double-path interferometer system on HL-2A has been modified to include a polarimeter capability in order to measure Faraday rotation. The polarimeter utilizes one phase technique, which is based on a Veron-type HCN laser interferometer and ``Dodel and Kunz''-type polarimeter including a rotating grating to shift the frequency of one probing beam by Δω, and two counter-rotating circularly-polarized probing beams. The Faraday rotation angle can be directly determined by measuring the plasma birefringence. The implementation of this instrument only needs one HCN laser source and one detector to characterize the rotation. The first experimental results have shown that the Faraday rotation angle of less than 1° can be measured with up to 0.1 ms time resolution.

The radial motion and structure of edge turbulence in the HuanLiuqi-2A tokamak [Y. Liu et al., Nucl. Fusion 45, S239 (2005)] was measured with visible spectroscopy diagnostic system; the radial turbulence propagation velocity and correlation length were evaluated by time-delay correlation technique and there were typically Vr=0.4–1 km/s and Lr=2–6 cm, respectively. The edge intermittent events accompanied with turbulence have been observed in plasma edge and propagated outward radially; especially through the scrape-off layer, the fluctuation signals of Dα exhibit strong asymmetric probability distribution functions (PDFs). Their propagation trajectories and radial velocity PDFs were inferred from a special correlation technique and the results indicated the radial velocity of intermittent event depends on its amplitude. Some comparisons with previous measurements and models were also presented.

A fast electron bremsstrahlung (FEB) diagnostic technique based on cadmium telluride (CdTe) detector has been developed recently in the HL-2A tokamak for measurements of the temporal evolution of FEB emission in the energy range of 10-200 keV. With a perpendicular viewing into the plasma on the equatorial plane, the hard x-ray spectra with eight different energy channels are measured. The discrimination of the spectra is implemented by an accurate spectrometry. The system also makes use of fast digitization and software signal processing technology. An ambient environment of neutrons, gammas, and magnetic disturbance requires careful shielding. During electron cyclotron resonance heating, the generation of fast electrons and the oscillations of electron fishbone (e-fishbone) have been found. Using the FEB measurement system, it has been experimentally identified that the mode strongly correlates with the electron cyclotron resonance heating produced fast electrons with 30-70 keV.

In the present paper, it is reported that a large production of runaway electrons has been observed during the flattop phase of electron cyclotron resonance heating (ECRH) discharges and in the presence of supersonic molecular beam injection (SMBI) in the HuanLiuqi-2A (commonly referred to as HL-2A) [Q. W. Yang, Nucl. Fusion 47, S635 (2007)] tokamak. For the set of discharges carried out in the present experiment, the ranges of ECRH power and plasma electron density are 0.8–1.0 MW and (3.0–4.0)×1019 m−3, respectively. A large number of superthermal electrons are produced through the avalanche effect [A. Lazaros, Phys. Plasmas 8, 1263 (2001)] during ECRH. The loop voltage increase due to SMBI gives rise to a decline in the critical runaway energy, which leads to that many superthermal electrons could be converted into runaway region. Therefore, this phenomenon may come from the synergetic effects of ECRH and SMBI. That is, the superthermal electrons created by ECRH are accelerated into runaway regime via t...

A new soft x-ray pulse height analysis (PHA) array including nine independent subsystems, on basis of a nonconventional software multichannel analysis system and a silicon drift detector (SDD) linear array consisting of nine high performance SDD detectors, has been developed in the HL-2A tokamak. The use of SDD has greatly improved the measurement accuracy and the spatiotemporal resolutions of the soft x-ray PHA system. Since the ratio of peak to background counts obtained from the SDD PHA system is very high, p/bor = 3000, the soft x-ray spectra measured by the SDD PHA system can approximatively be regarded as electron velocity distribution. The electron velocity distribution can be well derived in the pure ohmic and auxiliary heating discharges. The performance of the new soft x-ray PHA array and the first experimental results with some discussions are presented.

A 12-tip poloidal probe array is used on the HT-7 superconducting tokamak [Li, Wan, and Mao, Plasma Phys. Controlled Fusion 42, 135 (2000)] to measure plasma turbulence in the edge region. Some statistical analysis techniques are used to characterize the turbulence structures. It is found that the plasma turbulence is composed of multiscale coherent structures, i.e., turbulent eddies and there is self-similarity in a relative short scale range. The presence of the self-similarity is found due to the structural similarity of these eddies between different scales. These turbulent eddies constitute the basic convection cells, so the self-similar range is just the dominant scale range relevant to transport. The experimental results also indicate that the plasma turbulence is dominated by low-frequency and long-wavelength fluctuation components and its dispersion relation shows typical electron-drift-wave characteristics. Some large-scale coherent structures intermittently burst out and exhibit a very long pol...