EAST steady-state long pulse H-mode with core-edge integration for CFETR

Recent EAST experiment has successfully demonstrated long pulse steady-state high plasma performance scenario and core-edge integration since the last IAEA in 2018. A discharge with a duration over 60s with βP ~2.0, βN ~1.6, H98y2~1.3 and internal transport barrier on electron temperature channel is obtained with multi-RF power heating and current drive. A higher βN (βN~1.8, βp~2.0, H98y2~1.3, ne/nGW~0.75) with a duration of 20s is achieved by using the modulated neutral beam and multi-RF power, where several normalized parameters are close or even higher than the phase III 1GW scenario of CFETR steady-state. High-Z impurity accumulation in the plasma core is well controlled in a low level by using the on-axis ECH. Modelling shows that the strong diffusion of TEM turbulence in the central region prevents tungsten impurity to accumulate. More recently, EAST has demonstrated compatible core-edge integration discharges in the high βp scenario: high confinement H98y2>1.2 with high βP~2.5/βN~2.0 and fbs~50% is sustained with reduced divertor heat flux at high density ne/nGW~0.7 and moderate q95~6.7. By combining active impurity seeding through radiative divertor feedback control and strike point splitting induced by resonant perturbation coil, the peak heat flux is reduced by 20-30% on the ITER-like tungsten divertor, here a mixture of 50% neon and 50% D2 is applied.

Achievements of Actively Controlled Divertor Detachment Compatible with Sustained High Confinement Core in DIII-D and EAST

The compatibility of efficient divertor detachment with high-performance core plasma is vital to the development of magnetically controlled fusion energy. The joint research on the EAST and DIII-D tokamaks demonstrates successful integration of divertor detachment with excellent core plasma confinement quality, a milestone towards solving the critical Plasma-wall-interaction (PWI) issue and core-edge integration for ITER and future reactors. In EAST, actively controlled partial detachment with Tet,div ~ 5 eV around the strike point and H98 > 1 in different H-mode scenarios including the high βP H-mode scenario have been achieved with ITER-like tungsten divertor, by optimizing the detachment access condition and performing detailed experiments for core-edge integration. For active long pulse detachment feedback control, a 30s H-mode operation with detachment-control duration being 25s has been successfully achieved in EAST. DIII-D has achieved actively controlled fully detached divertor with low plasma electron temperature (Tet,div ≤ 5 eV across the entire divertor target) and low particle flux (degree of detachment, DoD >3), simultaneously with very high core performance (βN ~3, βP >2 and H98~1.5) in the high βP scenario being developed for ITER and future reactors. The high-βP high confinement scenario is characterized by an internal transport barrier (ITB) at large radius and a weak edge transport barrier (ETB, or pedestal), which are synergistically self-organized. Both the high-βP scenario and impurity seeding facilitate divertor detachment. The detachment access leads to the reduction of ETB, which facilitates the development of an even stronger ITB at large radius in the high βP scenario. Thus, this strong large radius ITB enables the core confinement improvement during detachment. These significant joint DIII-D and EAST advances on the compatibility of high confinement core and detached divertor show a great potential for achieving a high-performance core plasma suitable for long pulse operation of fusion reactors with controllable steady-state PWIs.

Development of high-power, long-pulse, multi-frequency ECH/CD system for JT-60SA

A gyrotron and a matching optics unit (MOU) for the multi-frequency electron cyclotron heating and current drive (ECH/CD) system in JT-60SA have been developed successfully. The gyrotron demonstrated stable operation at high powers of 1.5 MW for 5 s and 1.9 MW for 1 s at 110 GHz. To obtain high HE11 mode purity (> 90%) at the outlet of the waveguide in the ECH/CD launcher, a MOU for operating at three frequencies of 82 GHz, 110 GHz, and 138 GHz that includes three pairs of water-cooled phase correcting mirrors has been developed, which allows the mirrors to be changed without opening the evacuated MOU. The mode purity at the inlet of a dummy load in the transmission line was evaluated at high-power and an HE11 mode purity of > 90% was obtained at three frequencies.

Current drive experiments in SST1 tokamak with lower hybrid waves

The steadystate superconducting tokamak (SST1) is aimed to demonstrate long pulse plasma discharges employing non-inductive current drive by means of lower hybrid current drive (LHCD) system. The major and minor radius of the machine is 1.1m and 0.2m respectively. The LHCD system for SST1 comprises of klystrons, each rated for 0.5MW-CW rf power at a frequency of 3.7 GHz. The grill antenna comprises of two rows, each row accommodating 32 waveguide elements. Electron cyclotron resonance (ECR) breakdown assisted Ohmic plasma is formed in SST1 to overcome the issues associated with low loop voltage start-ups. With recent modifications in the poloidal coils configuration, even with narrow EC pulse (~50ms), good repeatable and consistent Ohmic plasmas could be produced which helped in carrying out LHCD current drive experiments on SST1. These experiments demonstrated both fully as well as partially driven non-inductive plasma current in SST1 tokamak. Discharges with zero loop voltages were obtained. The interaction of lower hybrid waves with plasma and generation of suprathermal electrons could be established using energy spectra measured by CdTe detectors. Various other signatures like drop in loop voltages, negative loop voltages, spikes in hard x-rays and increase in 2nd harmonic ECE signal, further confirmed the current drive by LHW’s. The beneficial effect of LHW’s in suppressing hard x-rays was also demonstrated in these experiments. The non-inductive current drive in SST1 could also be established by modulating LH power. The longest discharge of ~650ms could be obtained in SST1 with the help of LHW’s. In this paper, the experimental results obtained with LHCD experiments on SST1 is reported and discussed in more details.

English MODULATION OF MELATONIN SECRETION WITH TRANSCUTANEOUS AURICULAR NERVE STIMULATION: A CASE STUDY

The main study objective was to test the hypothesis that selective electrical transcutaneous auricular nerve stimulation (tANS) under forenoon daylight conditions induces melatonin secretion in a 64-year-old male patient with angina pectoris, hypercholesterolomy and coronary artery disease, assuming that it has beneficial effects on accompanied insomnia (Regensburg Insomnia Scale (RIS) = 22 points, the total score ranges from 0 to 40). Silicone stimulation plugs, with two platinum stimulating cathodes each, were inserted into the left and right external ears. Afterwards, one-second-long pulse trains of cathodic, biphasic and current regulated stimulating pulses at stimulating charge density Cd of 50.88 µC/cm2 and frequency of 25 Hz, were delivered for 30 min to selected sites at the upper and lower part of the left and right Cymba Conchae (CC), respectively. The common anode was attached to the neck. The time gap between the pulse trains was measured by the patient using a tactile sensor and was about 250 ms. The results showed that selective tANS under forenoon daylight conditions increased melatonin saliva levels in all the trials accomplished in a patient. Precisely, the lowest increase was obtained in trials with lower right (LR) CC, while the highest increase was obtained in upper-right (UR) CC trials.

Wettability, Microhardness, Wear and Corrosion Resistance of Ni–Co–P–BN(h)–Al2O3 Binary Nanocomposite Coatings Surface with Varying Long-Pulse Laser Parameters

In this study, Ni–Co–P–BN(h)–Al2O3 binary nanocomposite coatings were fabricated on steel C1045 substrates by jet electrodeposition. The samples were then processed using self-made laser processing equipment to investigate the influence of long-pulse laser processing parameters variation on samples’ surface morphology, roughness and wettability. Additionally, the properties of samples before and after laser processing were analyzed and characterized. The results showed that the surface morphologies, surface roughness and wettability of samples were affected by laser output power, pulse width and spot-to-spot distance variation. A convex dome was formed on the samples’ surface at a low laser output power and a suitable pulse width, while a dimple was formed on the samples’ surface at a high laser output power. The surface roughness and water contact angle of samples increased with the rise in laser output power or pulse width. The water contact angle decreased with the rise in the spot-to-spot distance, and the water contact angle reached a maximum value of 139.8° with a laser output power of 50 W, a pulse width of 100 µs and a spot-to-spot distance of 150 µm. The samples after laser processing exhibited a higher wettability, microhardness and wear resistance compared to those of the normal samples. The microhardness of the heat-affected zone reached a maximum value of 812.1 HV0.1, and the wear scar width of the samples reached a minimum value of 360.5 µm. However, after laser processing, the samples’ seawater corrosion resistance decreased slightly.

The performance of neutron diffractometers at long and short pulse spallation sources: Comparison between ESS and J-PARC

The general performance of diffractometers at the first long pulse spallation source ESS, is compared with their counterparts at J-PARC, a short pulse spallation source. The difference in the inherent pulse structure of these neutron sources presents opportunities for new concepts for instrumentation, where performance does not scale simply with source power. The article describes advantages and disadvantages of those diffractometers, adapting to the very different source characteristics. We find that the two sources offer comparable performance in flux and resolution when operating in high-resolution mode. ESS offers significant advantages in tunability and flexibility, notably in the ability to relax resolution in order to increase flux for a given experiment. The slow repetition rate of ESS favors long instruments. On the other hand, J-PARC instruments perform very well in spite of the lower source power and allow better access to epithermal neutrons, of particular interest for PDF analysis of diffraction data.

Advanced Insulation Materials for Facades: Analyzing Detachments Using Numerical Simulations and Infrared Thermography

In building construction, it is very important to reduce energy consumption and provide thermal comfort. In this regard, defects in insulating panels can compromise the capability of these panels of reducing the heat flow by conduction with the surroundings. In recent years, both experimental techniques and numerical methods have been used for investigating the effect of defects on the thermal behavior of building panels. The main novelty of this work regards the application of both numerical and experimental approaches based on infrared thermography techniques for studying the effects of defects such as debonding on the insulation properties of cork panels. In particular, the effects of defects were investigated by using the Long Pulse Thermography technique and then by analyzing the thermal behavior of the panel during the cooling phase. Results show the capability of the proposed approaches in describing the effects of defects in cork panels such as detachments and the benefit effect of a shield coating in improving the insulation properties of the panel.

Theoretical and Experimental Investigation on Temperature Rise of CFRP with Long Pulse Laser Irradiation

Carbon fiber reinforced polymers (CFRP) are a widely used composite material applied in both commercial and industrial utilization. Based on the heat conduction theory, a theoretical model for the temperature rise of braided CFRP irradiated by long pulse laser is established in this work, and the time required for the maximum temperature rise of CFRP (with different thicknesses) to be acted by long pulse laser with different energy densities and pulse widths is simulated. At the same time, the temperature rise experiment and damage morphology of a long pulse laser with braided CFRP were carried out. The theoretical simulation results are in good agreement with the experimental results, which verifies the correctness of the theoretical model. The results of this paper will provide a theoretical basis for laser processing of CFRP.