Radial transport dynamics studies of SMBI with a newly developed TPSMBI code

In tokamak plasma fueling, supersonic molecule beam injection(SMBI) with a higher fueling efficiency and a deeper penetration depth than the traditional gas puffing method has been developed and widely applied to many tokamak devices.It is crucial to study the transport dynamics of SMBI to improve its fueling efficiency, especially in the high confinement regime. A new one-dimensional(1D) code of TPSMBI has also been developed recently based on a six-field SMBI model in cylindrical coordinate. It couples plasma density and heat radial transport equations together with neutral density transport equations for both molecules and atoms and momentum radial transport equations for molecules. The dominant particle collisional interactions between plasmas and neutrals, such as molecule dissociation, atom ionization and charge-exchange effects, are included in the model. The code is verified to be correct with analytical solutions and also benchmarked well with the trans-neut module of BOUT++ code. Time-dependent radial transport dynamics and mean profile evolution are studied during SMBI with the TPSMBI code in both slab and cylindrical coordinates. Along the SMBI path, plasma density increases due to particle fuelling, while plasma temperature decreases due to heat cooling. Being different from slab coordinate, the curvature effect leads to larger front densities of molecule and atom during SMBI in cylindrical coordinate simulation.

Simulations of the effects of density and temperature profile on SMBI penetration depth based on the HL-2A tokamak configuration

Using the trans-neut module of the BOUT＋＋ code, we study how the fueling penetration depth of supersonic molecular beam injection（SMBI） is affected by plasma density and temperature profiles. The plasma densities and temperatures in L-mode are initialized to be a set of linear profiles with different core plasma densities and temperatures. The plasma profiles are relaxed to a set of steady states with different core plasma densities or temperatures. For a fixed gradient, the steady profiles are characterized by the core plasma density and temperature. The SMBI is investigated based on the final steady profiles with different core plasma densities or temperatures. The simulated results suggest that the SMB injection will be blocked by dense core plasma and high-temperature plasma. Once the core plasma density is set to be N（i0）= 1.4N0（N0= 1 × 10^19m^-3） it produces a deeper penetration depth. When N（i0） is increased from 1.4N0 to 3.9N0 at intervals of 0.8N0, keeping a constant core temperature of T（e0）= 725 eV at the radial position of ψ = 0.65, the penetration depth gradually decreases. Meanwhile, when the density is fixed at N（i0）= 1.4N0 and the core plasma temperature T（e0） is set to 365 eV,the penetration depth increases. The penetration depth decreases as T（e0） is increased from 365 eV to 2759 eV. Sufficiently large N（i0） or T（e0） causes most of the injected molecules to stay in the scrape-off-layer（SOL） region, lowering the fueling efficiency.

Favourable scenarios established by SMBI for the realization of the ELMy H-mode at HL-2A

The ELMy H-mode plasmas realized with the supersonic molecular beam injection（SMBI） are studied in relation to the energy confinement and the heating power for the L–H transition（P_（L-H） ） in the HL-2A tokamak. A database is assembled for this study based on the ELMy H-mode discharges during the experimental campaigns in the period 2009–2013at the HL-2A tokamak. The statistical results show that the SMBI is favourable for reaching the H-mode by reducing the heating power at the L–H transition and for the H-mode performance by improving the energy confinement compared with the ordinary gas puffing（GP）. The reduction of P_（L-H） is about 20% when the density is low, and the energy confinement enhancement factor of H_（H98y2）= τ_E/τ_（th,98y2） ≈ 1.5 is achieved with the SMBI. Note that in the database the density dependence of P_（L-H） is non-monotonic with the ˉne,min≈ 3×10^（19） m^（-3） at which the P_（L-H） is minimum. Most of P_（L-H） data are on the low density branch where the P_（L-H） increases with the decrease in density. The minimum of the P_（L-H） in HL-2A is comparable to the ITPA multi-machine threshold power scaling P_（thr_scal08）. The physics behind the reduction of the P_（L-H） with the SMBI is also investigated in relation to the change of the density gradient at the plasma edge, the gas fuelling efficiency, and the recycling.

Investigation of molecular penetration depth variation with SMBI fluxes

We study the molecular penetration depth variation with the SMBI fluxes.The molecular transport process and the penetration depth during SMBI with various injection velocities and densities are simulated and compared.It is found that the penetration depth of molecules strongly depends on the radial convective transport of SMBI and it increases with the increase of the injection velocity.The penetration depth does not vary much once the SMBI injection density is larger than a critical value due to the dramatic increase of the dissociation rate on the fueling path.An effective way to improve the SMBI penetration depth has been predicted,which is SMBI with a large radial injection velocity and a lower molecule injection density than the critical density.

基于改进YOLOv5s的香蕉树长势研究

为了提高香蕉长势的检测精准度以及检出率,文章参照香蕉的生长特性提出了一种基于改进YOLOv5s的香蕉长势研究方法,将处于生长发育时期内的三个主要时期的香蕉作为研究对象,将YOLOv5s目标检测算法作为基础构建模型,引入simAM无参注意力机制,采用SIoU替换YOLOv5s原损失函数,轻量化处理C3模块,将原模型卷积替换为MPconv,削减20*20的大目标检测层,引入BiFPN特征融合。经文章制备的香蕉树数据集验证,相较于基础YOLOv5s模型,改进后的SMBi-YOLOv5s模型的mAP提高了0.4%,模型参数量降低了76.6%,准确率提升了2.1%。

HL-2A装置超声分子束注入加料效率的研究

利用多道远红外HCN激光干涉仪实时测量了等离子体中的粒子数增量,首次得到了HL-2A等离子体偏滤器位形和孔栏位形下强场侧和弱场侧SMBI的加料效率,结果与法国Tore Supra装置的SMBI加料效率的范围相一致。

补充加料过程中逃逸电子的雪崩现象

在靶丸注入和超声分子束注入等补充加料期间 ,虽然等离子体密度骤然增加 ,但用五通道碘化汞探测器阵列及碘化钠探测器在此期间均测到很强的X射线辐射 ,且射线峰爆发时间与靶丸注入及超声分子束注入时间对应得相当好。用二次电子发射形成雪崩型逃逸电子理论解释了实验测量结果。

甘西鼠尾草注射液与丹参注射液对大鼠皮层神经细胞缺血性损伤保护作用的比较研究

目的:比较甘西鼠尾草注射液与丹参注射液对体外培养的大鼠大脑皮层神经细胞谷氨酸(Glu)损伤的保护作用。方法:分离培养新生(1d)大鼠大脑皮层神经细胞,加入Glu模拟兴奋性损伤,MTT法测定细胞存活率,比色法测定上清中LDH含量,细胞中SOD、GSH-Px活性、MDA含量。结果:皮层细胞经Glu损伤后,上清LDH含量、细胞中MDA含量显著增加,SOD和GSH-Px活力明显下降,甘西鼠尾草注射液与丹参注射液均可改善上述情况。结论:甘西鼠尾草注射液与丹参注射液可保护由Glu引起的大鼠大脑皮层神经细胞的损伤,其机理可能与抗脂质过氧化、清除自由基有关。

甘西鼠尾草注射液与丹参注射液对化学性缺氧小鼠能量代谢影响的比较

目的 :比较甘西鼠尾草注射液与丹参注射液对急性化学性缺氧小鼠能量代谢的影响。方法 :通过注射NaNO2 造成小鼠急性化学性缺氧 ,记录小鼠存活时间 ,用ATPase、LD检测试剂盒分别检测脑组织中Na+ K+ ATPase、Ca2 + ATPase和乳酸 (LD)含量 ,比较两药对能量代谢的影响。结果 :两药均可延长化学性缺氧小鼠存活时间 ,增强Na+ K+ ATPase。Ca2 + ATPase活力 ,降低LD含量 ,其中大剂量甘西鼠尾草注射液较大剂量丹参注射液更能增强Na+ K+ ATPase活力 ,而小剂量的甘西鼠尾草注射液在增强Ca2 + ATPase活力上较小剂量的丹参注射液作用更强 ;在降低缺氧小鼠脑组织LD含量方面 ,两药作用基本相似。结论 :丹参注射液和甘西鼠尾草注射液对缺氧小鼠的能量代谢均有改善作用。两药均可延长缺氧小鼠存活时间 ,降低脑组织LD含量 ,提高ATPase活力 。

Comparison of Supersonic Molecular Beam Injection from Both Low Field Side and High Field Side of HL-2A

SMBI （supersonic molecular beam injection）, as an effective fueling method for fusion plasmas, has been widely used on the HL-2A tokamak and other fusion devices. Two different types of SMBI system are now installed on HL-2A. One is an electromagnetic valve injector on the low field side （LFS）, and the other is a pneumatic valve injector on the high field side （HFS）. A new electron density record nc = 4.7× 10^19 m ^-3 which exceeds both the Oreenwald density limit and the maximum density obtained by gas puffing （GP）, was obtained on HL-2A with single-null-divertor operation. The HFS injection system is still under test, however, its outstanding fueling characteristics have already been observed, e.g. it has higher fueling efficiency compared to the LFS system. This excellent feature is still preserved during the process of ECRH.

HL-2A装置上粒子输运的研究

用密度调制的方法研究了等离子体中粒子输运问题。采用了注入脉冲式补充送气和超声分子束两种不同的密度调制方法。在HL-2A装置常规欧姆放电的情况下,运用有限差分法和Nagashima矩阵技术,求解了粒子平衡方程。计算出了粒子的输运系数(对流速度v和扩散系数D)。研究了粒子输运系数与等离子体线平均密度之间的关系。实验结果表明,在欧姆放电的情况下,等离子体芯部的粒子对流速度方向始终是向内的,并且密度低时,粒子输运系数(粒子扩散系数D和对流速度v)较大;密度高时,粒子输运系数较小。

The first results of divertor discharge and supersonic molecular beam injection on the HL-2A tokamak

HL-2A tokamak is the first tokamak with divertors in China. The plasma boundary and the position of the striking point on the target plates of the HL-2A closed diwrtor were simulated by the current filament code and they were in agreement with the diagnostic results in the divertor. Supersonic molecular beam injection （SMBI） system was first installed and tested on the HL-2A tokamak in 2004. In the present experiment low pressure SMBI fuelling on the HL-2A closed divertor was carried out. The experimental results indicate that the divertor was operated in the ＇linear regime＇ and during the period of SMB pulse injection into the HL-2A plasma the power density eonvected at the target plate surfaces was 0.4 times of that before or after the beam injection. It is a useful fuelling method for decreasing the heat load on the neutralizer plates of the divertor.

Plasma Response to Supersonic Molecular Beam Injection in J-TEXT

Recently, hydrogen fueling experiments with supersonic molecular beam injection （SMBI） system have been performed in the J-TEXT tokamak. To evaluate the effects of the in- jection amount of SMBI on plasma behaviors, moderate and intensive SMBs have been separately injected and compared with each other in Ohmic discharges. With moderate SMBs, electron den- sity increases about twice as before, the size of magnetic island slightly decreases, and the edge toroidal rotation speed in a counter-current direction, measured by a high resolution spectrometer （Carbon V ion, 227.09 nm, r/a-= 0.7-0.8）, is accelerated from 8 km/s to 12 km/s. The state of higher electron density with moderate SMBI can be maintained for a long period, which indicates that plasma confinement is improved. However, with intensive SMBs, the accompanied magne- tohydrodynamic （MHD） activities are triggered, and the electron density increases moderately. The edge toroidal velocity is decreased, in certain cases even reversed in the co-current direction. The statistical result of experimental data for moderate and intensive SMBs suggests a preferred fueling amount （less than 3.2 ~ 1019） to improve the SMBI fueling efficiency in experiments.

甘西鼠尾草注射液与丹参注射液对PC12细胞H_2O_2损伤保护作用比较研究

目的:比较甘西鼠尾草注射液与丹参注射液对PC12细胞H2O2损伤的保护作用。方法:采用细胞株培养的方法,建立PC12细胞H2O2损伤模型,通过MTT法和流式细胞分析仪检测细胞存活率和凋亡率;采用免疫细胞化学染色法检测PC12细胞bcl-2和bax表达。结果:PC12细胞经H2O2损伤后,细胞存活率降低、凋亡率增加,甘西鼠尾草注射液与丹参注射液处理组均可有效缓解上述改变(P<0.05);两药均使bcl-2表达增加(P<0.05),bax表达减少(P<0.05)。结论:甘西鼠尾草注射液与丹参注射液对PC12细胞H2O2损伤具有明显保护作用。其机理可能与增强凋亡抑制因子bcl-2表达、抑制凋亡促进因子bax表达,进而抑制细胞凋亡有关。

甘西鼠尾草注射液与丹参注射液对大鼠缺血再灌注损伤保护作用的比较

目的:比较甘西鼠尾草注射液与丹参注射液对大鼠缺血再灌注损伤的保护作用。方法:采用改良线栓法阻断大鼠大脑中动脉,建立脑缺血模型,到达再灌注时限后进行神经功能缺损评分,用试剂盒检测脑组织中NOS、NO含量,并计算脑组织含水量判定脑水肿情况;通过结扎双侧颈总动脉,考察两药对脑血管通透性的影响。结果:甘西鼠尾草注射液与丹参注射液均可改善缺血再灌注损伤大鼠神经功能缺损;降低脑组织中NOS、NO含量;降低脑血管通透性;对脑水肿也有一定的缓解作用。结论:甘西鼠尾草注射液与丹参注射液对大鼠缺血再灌注损伤均有保护作用,小剂量丹参注射液在降低脑水肿和神经功能缺损评分方面优于小剂量甘西鼠尾草注射液;大剂量甘西鼠尾草注射液在降低脑血管通透性方面优于等剂量的丹参注射液。

Spectral Analysis in EUV Range for Study of Core Impurity Behavior in HL-2A

Extreme ultraviolet （EUV） spectroscopy has been developed for impurity diagnostics in HL-2A tokamak. The EUV spectrometer consists of an entrance slit, a holographic varied-line- space （VLS） grating, a back-illuminated charge-coupled device （CCD） and a laser light source for optical alignment. Spectral lines in wavelength region of 20-500 A observed from HL-2A plasmas were analyzed to study the impurity behavior. Spectral and temporal resolutions used for the analysis were 0.19A at CV （2×33.73 ,h,） and 6 ms, respectively. It was found that carbon, oxygen and iron impurities were usually dominant in the HL-2A plasma. They almost disappeared when the siliconization was carried out. Although the EUV spectra were entirely replaced by the silicon emissions just after the siliconization, the emissions were considerably decreased with accumulation of discharges. Aluminum and neon were externally introduced into the HL-2A plasma based on laser blow-off （LBO） and supersonic molecular beam injection （SMBI） techniques for a trial of the impurity transport study, respectively. The preliminary result is presented for time behavior of EUV spectral lines.

Study of Divertor Heat Patterns Induced by LHCD L-Mode Plasmas Using an Infra-Red Camera System on EAST

Divertor heat patterns induced by Lower Hybrid Current Drive （LHCD） L-mode plasmas are investigated using an infra-red （IR） camera system on an Experimental Advanced Superconducting Tokamak （EAST）. A two-dimensional finite element analysis code DFlux is used to compute heat flux along the poloidal divertor target and corresponding quantities. Outside the Origin Strike Zone （OSZ）, a Second Peak Heat Flux （SPHF） zone, where the heat flux is even stronger than that at the OSZ, appears on the lower-outer （LO） divertor plates with LHCD and disappears immediately after switching off the LHCD. The main heat-flux shifts from the SPHF zone towards the OSZ when the divertor configuration converts from double null to lower single null, indicating that the growth of the SPHF zone is apparently affected by a plasma magnetic configuration. The heat patterns on the LO divertor plates are observed to be different from that on the lower-inner （LI） targets as the SPHF zone appears only on the LO divertor target. It is also found that the heat flux at the SPHF zone was obviously enhanced after the Supersonic Molecule Beam Injection （SMBI） pulse.

Simulation of helium supersonic molecular beam injection in tokamak plasma

To study helium(He)supersonic molecular beam injection(SMBI)into H-mode tokamak plasma,a simplified multicomponent-plasma model under the assumption of quasi-neutral condition is developed and implemented in the frame of BOUT++.The simulation results show that He species propagate inwards after He SMBI,and are deposited at the bottom of the pedestal due to intensive ionization and weak spreading speed.It is found that almost all injected helium particles strip off all the bounded electrons.He species interact intensively with background plasma along the injection path during He SMBI,making deuterium ion density profile drop at the He-deposited location and resulting in a large electron temperature decreasing,but deuterium ion temperature decreasing a little at the top of the pedestal.

Investigation of impurity transport using supersonic molecular beam injected neon in HL-2A ECRH plasma

In this paper, we describe the behavior of impurity transport in the HL-2A electron cyclotron resonance heating （ECRH） L-mode plasma. The neon as a trace impurity is injected by the supersonic molecular beam injection （SMBI） technique, which is used for the first time to study the impurity transport in HL-2A. The progression of neon ions is monitored by the soft X-ray camera and bolometer arrays with good temporal and spatial resolutions. The convection and diffusion process of the neon ions are investigated with the one-dimensional impurity transport code STRAHL. The results show that the diffusion coefficient D of neon ions is a factor of four larger than the neoclassical value in the central region. The value of D is larger in the outer region of the plasma （ρ 〉 0.6） than in the central region of the plasma （ρ 〈 0.6）. The convective velocity directs inwards with a value of ～-1.0 m/s in the Ohmic discharge, but it reverses to direct outwards with a value of ～ 8.0 m/s in the outer region of the plasma when ECRH is applied. The result indicates that the impurity transport is strongly enhanced with ECRH.

Heat Transport During H-Mode in the HL-2A Tokamak

Perturbative experiments on electron heat transport have been successfully con- ducted on the HL-2A tokamak. The pulse propagation of the electron temperature is induced by the supersonic molecular beam injection （SMBI）, which has characteristics of good localization and deep deposition. A model based on the electron heat transport in cylindrical geometry has been applied to reconstruct the measured amplitude and phase profiles of the electron temperature perturbation. The results show that the heat transport is significantly reduced near the pedestal region of the H-mode plasma. In the ＂profile stiffness/resilience＂ region, similar heat diffusivities have been observed in L-mode and H-mode plasmas, which verifies the gradient-driven transport physics in tokamaks.