Development of Terahertz FU CW Gyrotron Series for DNP

Abstract

The new gyrotron series in FIR FU, so-called Gyrotron FU CW Series, is being developed for application to high power THz technologies. The second gyrotron, of the series, Gyrotron FU CW II with an 8 T liquid He-free superconducting magnet has been constructed and the operation test was successfully carried out. It will be used for enhancing the sensitivity of 600 MHz proton-NMR by use of Dynamic Nuclear Polarization (DNP). The designed operation mode of the gyrotron is TE 2,6 at the second harmonic. The corresponding designed frequency is 394.6 GHz. The real operation frequency is 394.3 GHz at TE 06 mode, because of fabrication error of the diameter of the cavity. The operation is in complete CW at the output power of around 30 W or higher at the TE 06 cavity mode. There are many other operation modes at the fundamental and the second harmonics. Typical output power of the fundamental and the second harmonic are higher than 100 W and 20 W, respectively. The third gyrotron, Gyrotron FU CW III with 20 T superconducting magnet has already been constructed and the operation test has been almost completed. The highest frequency is around 980 GHz at the second harmonic operation. This gyrotron demonstrates a possibility of application to higher frequency DNP/NMR up to 1 GHz.

Development and Applications of High—Frequency Gyrotrons in FIR FU Covering the sub-THz to THz Range

“…The output frequency of 394.6 GHz corresponds to an electron spin resonance (ESR) at a magnetic field about 14 T, while the frequency of the proton NMR at such intensity of the magnetic field is 600 MHz. The first experimental results from the tests of the tube in both a pulse and a CW mode of operation at the fundamental and at the second harmonic have been presented in [27]. The observed output power for three of the design modes as a function of the beam current is presented in Fig.…”

Gyrotron Development for High Power THz Technologies at IAP RAS

“…Terahertz frequency range 0.1-10 THz, which occupies an intermediate position in the electromagnetic spectrum between the microwave and optical ranges, has a number of specific features that make it very attractive for a wide range of fundamental and applied researches in physics, chemistry, biology and medicine [1][2][3][4][5]. Indeed, in this range there are a large number of molecules (including organics) with strong spectrum lines.…”

Continuously Frequency Tunable High Power Sub-THz Radiation Source—Gyrotron FU CW VI for 600 MHz DNP-NMR Spectroscopy

“…Now, the series is being applied for development of high power THz technologies in wide-ranging fields [15]. High frequency gyrotrons are the only radiation sources which will open the high power THz technologies such as DNP-NMR spectroscopy [16][17][18][19], X-ray detected magnetic resonance (XDMR) measurement [20], ESR measurement in THz region [21], plasma scattering measurement [22], accurate measurement on hyperfine structure of positronium [23], etc.…”