The first demonstration of rocket exhaust driven amplification (REDA) of whistler mode waves occurred on May 26, 2020 by transferring energy from pickup ions in a rocket exhaust plume to EM waves. The source of coherent VLF waves was the Navy NML Transmitter at 25.2 kHz located in LaMoure, North Dakota. The topside ionosphere at 480 km altitude became an amplifying medium with a 60 s firing of the Cygnus BT‐4 engine. The rocket engine injected exhaust as a neutral cloud moving perpendicular to field lines that connected the NML transmitter to the VLF Radio Receiver Instrument (RRI) on e‐POP/SWARM‐E. Charge exchange between the ambient O⁺ ions and the hypersonic water molecules in the exhaust produced H₂O⁺ ions in a ring‐beam velocity distribution. The 25.2 kHz VLF signal from NML was amplified by 30 dB for a period 77 s as observed by the RRI. Simultaneously, preexisting coherent ELF waves at 300 Hz were amplified by 50 dB during and after the Cygnus burn. Extremely strong coherent emissions and quasiperiodic bursts in the 300–310 Hz frequency range lasted for 200 s after the release. The excitation of an ELF whistler cavity may have lasted even longer, but the orbit of the SWARM‐E/e‐POP moved the RRI sensor away from the wave emission region. The amplified 300 Hz ELF waves may have gained even more energy by cyclotron resonance with radiation belt electrons as they were ducted between geomagnetic‐conjugate hemispheres.

中文翻译：

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使用卫星火箭发动机注入的中性气体，可强烈放大太空中的ELF / VLF信号

惠斯勒模式波的火箭排气驱动放大（REDA）的首次演示发生在2020年5月26日，其过程是将能量从火箭排气羽流中的吸收离子转移到EM波。相干VLF波的来源是位于北达科他州LaMoure的25.2 kHz的海军NML发射机。天鹅座BT-4发动机点火60秒钟后，海拔480 km的电离层成为放大介质。火箭发动机将废气作为中性云喷射，并垂直于将NML发送器连接到e-POP / SWARM-E上的VLF无线电接收器（RRI）的磁力线移动。周围的O ⁺离子与排气中的高超声速水分子之间的电荷交换产生H ₂ O ⁺离子在环束速度分布中的分布。RRI观察到，来自NML的25.2 kHz VLF信号被放大了30 dB，持续了77 s的时间。同时，在天鹅座烧伤期间和之后，先前存在的300 Hz相干ELF波被放大了50 dB。释放后，在300-310 Hz频率范围内极强的相干发射和准周期突发持续了200 s。ELF吹口哨腔的激励可能持续了更长的时间，但是SWARM-E / e-POP的轨道使RRI传感器远离了波发射区域。当放大的300 Hz ELF波被输送到地磁共轭半球之间时，它们可能通过辐射带电子的回旋共振而获得了更多的能量。