As the wafer size increases, pulsed dual frequency inductively coupled plasma sources have been proposed as an effective method to achieve large-area uniform plasmas. A two-dimensional (2D) self-consistent fluid model, combined with an electromagnetic module, has been employed to investigate the influence of the pulse duty cycle and the pulse phase shift on the plasma radial uniformity in an argon discharge. When both antennas are pulsed, the best radial uniformity is obtained at 30%, due to the balance between the positive feedback and diffusion loss. When the duty cycle decreases, the bulk plasma density becomes lower since the power absorption is limited during the shorter active-glow period. As the duty cycle decreases to 10%, the plasma density is characterized by an edge-high profile because of the strong diffusion. When the pulse duty cycle of the outer two-turn coil is fixed at 70%, the plasma density profiles shift from center-high over uniform to edge-high as the pulse duty cycle of the inner coil decreases from 50% to 10%, and the best plasma uniformity appears at 30%. In addition, by adjusting pulse phase shifting of two antennas, the plasma uniformity could also be improved, and the nonuniformity degree decreases from 0.138 for the synchronous pulse to about 0.101 for the asynchronous pulse.

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A fluid model is employed to investigate the effect of radio frequency bias on the behavior of an argon inductively coupled plasma (ICP). In particular, the effects of ICP source power, single-frequency bias power, and dual-frequency bias power on the characteristics of ICP are simulated at a fixed pressure of 30 mTorr (1 Torr = 1.33322 × 102 Pa). When the bias frequency is fixed at 27.12 MHz, the two-dimensional (2D) plasma density profile is significantly affected by the bias power at low ICP source power (e.g., 50 W), whereas it is weakly affected by the bias power at higher ICP source power (e.g., 100 W). When dual-frequency (27.12 MHz/2.26 MHz) bias is applied and the sum of bias powers is fixed at 500 W, a pronounced increase in the maximum argon ion density is observed with the increase of the bias power ratio in the absence of ICP source power. As the ratio of 27.12-MHz/2.26-MHz bias power decreases from 500 W/0 W to 0 W/500 W with the ICP source power fixed at 50 W, the plasma density profiles smoothly shifts from edge-high to center-high, and the effect of bias power on the plasma distribution becomes weaker with the bias power ratio decreasing. Besides, the axial ion flux at the substrate surface is characterized by a maximum at the edge of the substrate. When the ICP source power is higher, the 2D plasma density profiles, as well as the spatiotemporal and radial distributions of ion flux at the substrate surface are characterized by a peak in the reactor center, and the distributions of plasma parameters are negligibly affected by the dual-frequency bias power ratio.

The fully-wrapped carbon fiber reinforced cylinders with an aluminum liner are currently the most common high-pressure hydrogen storage tank for vehicles. However, it is difficult to detect it by traditional detection methods effectively. X-ray digital radiographic inspection technology is currently a feasible way to detect the typical defects of the winding layer and aluminum liner of the fully-wrapped carbon fiber reinforced cylinders with an aluminum liner for vehicles. In order to verify the detection ability of digital radiographic inspection for the main defects of carbon fiber wound gas cylinders with aluminum liner and to provide quantitative data of the detection ability, this paper aims at the fiber layer fracture, scratches, and pores that may occur during the use and manufacture of gas cylinders. In order to simulate the above-mentioned natural defects, the images of artificial defects were taken through the optimized transillumination parameters. The test results show that the digital radiographic inspection method can detect the axial notches, circumferential notches, oblique notches with a depth of 0.2 mm on the fiber layer, and axial and circumferential notches with a depth of 0.2 mm on the liner. Furthermore, it can also detect artificial defects such as 0.5mm fiber layer flat-bottom hole and 0.2mm depth /Φ1mm aluminum liner flat-bottom hole. This proves that digital radiographic inspection can be used for the early stage of a significant failure of the fully-wrapped carbon fiber reinforced cylinders with an aluminum liner and provides strong support for its safe use.

With the development of hydrogen fuel cell vehicles, Carbon Fiber Wrapped Cylinder with Aluminum Liner are widely used in the field of the on-board storage of compressed hydrogen. Impact damages are common in Carbon Fiber Wrapped Cylinder with Aluminum Liner because the composite laminate structure is sensitive to impact load. In this work, the DR method with the technology of compensation block is used to detect impact damage of Carbon Fiber Wrapped Cylinder with Aluminum Liner, and analyzes the expansion of impact damage after different number of pressure cycles. The main damage of Carbon Fiber Wrapped Cylinder with Aluminum Liner caused by impact are delamination of carbon fiber overwrap, debonding between cylinder liner and carbon fiber overwrap, and bulge inward of aluminum liner, and these damages become more serious as the impact energy increases from 500 J to 1500 J. As the pressure cycle test is performed to the Carbon Fiber Wrapped Cylinder with Aluminum Liner, the impact has a serious effect on the fatigue performance of the cylinder. In addition, the debonding between the cylinder liner and the carbon fiber overwrap and the bulge inward degree of the aluminum liner are reduced due to the internal pressure. When the impact energy is low (i.e., 500 J), the pressure cycle has no significant influence on the delamination defect of carbon fiber overwrap. Besides, under the high impact energy conditions (i.e., 1000 J and 1500 J), the delamination defect of the overwrap in the impact center appears obvious expansion with the pressure cycle, while the delamination defect at the impact edge does not propagate obviously.