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Keyhole cutting of carbon fiber reinforced polymer using a long-duration nanosecond pulse laser
摘要： The machining performance of a high-energy nanosecond pulse laser with a near-infrared wavelength is investigated for carbon fiber-reinforced polymer (CFRP) with two different fiber arrangements. This research work demonstrates for the first time that a keyhole mode cutting can be achieved for CFRP materials using a high-energy nanosecond pulse laser of a Long Pulse mode (120 ns). Specifically, it is shown that the short-duration Q-Switch mode (8 ns) results in ineffective material removal for CFRP, despite much higher peak laser power intensity than the Long Pulse mode. In Long Pulse mode, multi-pass straight line and contour cutting experiments are further performed to investigate the effect of laser processing parameters and resultant machined surface integrity. Plasma absorption effects using both pulse modes are discussed. The results show that a 2.2 mm thick cross-ply CFRP panel can be cut through using as few as 6 laser passes, and a high-quality machined surface can be produced with a limited heat-affected zone and minimal fiber pull-out using Argon assist gas. The successful outcomes from this work provide the key to enable efficient CFRP laser machining using high-energy nanosecond pulse lasers, and offer insight into the unique energy absorption mechanisms for CFRP laser machining.
关键词： Laser cutting,Keyhole,Long pulse,Nanosecond pulse laser,Carbon fiber reinforced polymer
更新于2025-11-21 11:08:12
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Long-Pulse Uncooled Copper Magnet for Gyrotron
摘要： The operation of a gyrotron requires a strong, stable magnetic ?eld over time. Working in the CW mode requires complex/cryogen solenoid cooling systems. Working in the pulse mode is possible with a simple solenoid, but only for short pulses, typically up to 50 μs. In this article, an intermediate working point for the gyrotron is presented: a pulsed gyrotron with a simple uncooled solenoid, which is capable of producing relatively long pulses of ～10 ms. To power a longer pulse with a simple solenoid, a super-capacitor (SC)-based system has been designed, which enables the extension of the operation of pulsed gyrotrons to tens of milliseconds, while keeping the system simplicity, without a cooling system for the solenoid. The setup was realized and a 27-ms current pulse of 1.1 kA was obtained through a gyrotron with a simple copper solenoid with a stability of ～0.3%. A 5-kW/10-ms radiation pulse at 28 GHz was measured from the gyrotron. This setup enables the use of a rather simple solenoid and a gyrotron and still obtains a rather long radiation pulse. This concept may open a new regime for pulsed gyrotrons.
关键词： Gyrotron,long pulse,magnetic ?eld,solenoid,millimeter wave
更新于2025-09-11 14:15:04
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Investigation of an $X$-Band Long Pulse High-Power High-Gain Coaxial Multibeam Relativistic Klystron Amplifier
摘要： Increasing the output power of the microwave is one of the most important development directions for high-power microwave (HPM) technology. However, when the output power is increased, the radio frequency breakdown would occur owing to superhigh electric field strength. This problem limits the power handling capability of a single-HPM generator, and this problem becomes more serious for high-frequency bands and long pulse. One solution to overcome this problem is coherent power combining, and coherent power combining can achieve an equivalent power of the order of TW. The relativistic klystron amplifier (RKA) is a promising candidate for coherent power combing owing to its character of controllable frequency and steady phase. However, the radiation power of RKA quickly decreases when the source is scaled up to higher frequencies such as X-band, and moreover, the multigigawatts long pulse radiation from RKA at the X-band has not yet been obtained experimentally. In this paper, we present investigations into an X-band coaxial multibeam RKA, The power handling capability was increased by introducing 20 electron drift tubes and a four gaps extended interaction output cavity. The amplitude uniformity of the multiple electron beams was improved by optimized the anode and cathode configuration. Then, a radiation power of 2.2 GW with pulsewidth of 120 ns is generated experimentally; the working frequency and amplifier gain are 9.4 GHz and 50 dB, respectively.
关键词： Coaxial multibeam relativistic klystron amplifier (CMB-RKA),X-band,long pulse,high-power microwave (HPM)
更新于2025-09-10 09:29:36