Abstract
The gyrotrons are powerful sources of coherent radiation that can operate in both pulsed and CW (continuous wave) regimes. Their recent advancement toward higher frequencies reached the terahertz (THz) region and opened the road to many new applications in the broad fields of high-power terahertz science and technologies. Among them are advanced spectroscopic techniques, most notably NMR-DNP (nuclear magnetic resonance with signal enhancement through dynamic nuclear polarization, ESR (electron spin resonance) spectroscopy, precise spectroscopy for measuring the HFS (hyperfine splitting) of positronium, etc. Other prominent applications include materials processing (e.g., thermal treatment as well as the sintering of advanced ceramics), remote detection of concealed radioactive materials, radars, and biological and medical research, just to name a few. Among prospective and emerging applications that utilize the gyrotrons as radiation sources are imaging and sensing for inspection and control in various technological processes (for example, food production, security, etc). In this paper, we overview the current status of the research in this field and show that the gyrotrons are promising radiation sources for THz sensing and imaging based on both the existent and anticipated novel techniques and methods.
Highlights
The recent years are witnessing remarkable progress and the proliferation of various applications that are utilizing electromagnetic radiation with terahertz frequencies belonging to the so-called terahertz (THz) gap, which nowadays is more frequently referred to as the last frontier of the electromagnetic spectrum
The spectroscopy based on nuclear magnetic resonance (NMR) is a powerful and widely used method for studying a big variety of compounds in biomolecular research, material, and pharmaceutical sciences
Its principle is grounded on the fact. Another technique that benefits from the high-output power of the sub-THz gyrotrons is the that when beamed on the target, the millimeter-wave gyrotron radiation generates rapid transient long-range sensing increases based on active thermal
Summary
The recent years are witnessing remarkable progress and the proliferation of various applications that are utilizing electromagnetic radiation with terahertz frequencies belonging to the so-called terahertz (THz) gap, which nowadays is more frequently referred to as the last frontier of the electromagnetic spectrum. A conventional figure of merit that characterizes the latter devices, as well as the high-power microwave tubes, is given by the product of the average output power P and the frequency f squared (P f 2 ) With respect to this value, the gyrotrons are among the most powerful sources of both pulsed and CW (continuous wave) coherent radiation in the terahertz frequency range and recently are contributing significantly to bridging the THz gap, providing terahertz waves for different applications in the fundamental scientific research and the technologies [19,20]. The gyrotrons are vacuum electron tubes that belong to the family of gyro-devices, of which other prominent members are the Gyro-Klystrons, Gyro-TWT (Traveling-Wave Tubes), Gyro-BWO (Backward-Wave Oscillators), and CARM (Cyclotron Autoresonance Masers) All of these utilize hollow electron beams in which the electrons follow helical orbits gyrating with a cyclotron frequency Ωc in a strong magnetic field B.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
