Experimental results and numerical simulations of a high power 140 GHz gyrotron

Gantenbein, G.; Borie, E.; Dammertz, G.; Kuntze, M.; Nickel, H.-U.; Piosczyk, B.; Thumm, M.

doi:10.1109/27.338301

Cited by 31 publications

(3 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As far as the wall loading is concerned, all these modes tend to operate well within the limitation of 1 kW/cm 2 for ideal copper and one can produce a suitable transverse output coupling scheme effectively. This confirmed earlier studies that indicated that the TE 10,4 mode is good for operation at 140 GHz with an output power of around 500 kW [12,13] (see also [2]). At 140 GHz the wall loading is too high for CW operation at 500 kW.…”

Section: Mode Selection and Starting Current Calculationssupporting

confidence: 91%

CONCEPTUAL DESIGN STUDIES OF AN 84 GHz, 500 kW, CW GYROTRON

Kartikeyan

Singh

Borie³

et al. 2007

Int J Infrared Milli Waves

Self Cite

View full text Add to dashboard Cite

The feasibility of an 84 GHz, 500 kW, CW gyrotron for ECRH on an experimental tokamak will be presented in this paper. Mode competition and mode selection procedures are carefully investigated by considering various candidate modes and the TE 10,4 mode is chosen as the operating mode. A conventional cylindrical cavity resonator with weak input and output tapers and parabolic roundings is considered for interaction studies. Selfconsistent, both single-mode and time-dependent, calculations are carried out and power and efficiencies are computed for a typical set of beam parameters. The results show that an output power of well over 500 kW, CW and efficiency around 40% can be reached without a depressed collector.

show abstract

Section: Mode Selection and Starting Current Calculationssupporting

confidence: 91%

CONCEPTUAL DESIGN STUDIES OF AN 84 GHz, 500 kW, CW GYROTRON

Kartikeyan

Singh

Borie³

et al. 2007

Int J Infrared Milli Waves

Self Cite

View full text Add to dashboard Cite

show abstract

“…If another mode is excited, the generated microwave power will be trapped inside the gyrotron tube because the quasi-optical output mirror assembly is designed only for the particular frequency of the operating mode. Several numerical or experimental publications have discussed the fact that such uncontrolled reflection can decrease the onset of nonstationary oscillations [10,11,12], competing transverse modes [13,14], or directly decrease the generated power [5,15].…”

Section: Introductionmentioning

confidence: 99%

Study of the Effect of Reflections on High-Power, 110-GHz Pulsed Gyrotron Operation

Genoud

Picard

Schaub

et al. 2021

J Infrared Milli Terahz Waves

View full text Add to dashboard Cite

The effect of reflection is studied experimentally and theoretically on a high-power 110 GHz gyrotron operating in the TE 22,6 mode in 3 µs pulses at 96 kV, 40 A. The experimental setup allows variation of the reflected power from 0 to 33 % over a range of gyrotron operating conditions. The phase of the reflection is varied by translating the reflector along the axis. Operating at a higher efficiency point, at 4.40 T with 940 kW of output power, reflected power exceeding 11% causes a switch from operation in the TE 22,6 to simultaneous operation in the TE 22,6 and TE 21,6 modes with a large decrease of the total gyrotron output power. This switching effect is in good agreement with simulations using the MAGY code. Operating at a more stable point, 4.44 T with 580 kW of output power, when the reflection is increased, the output power remains in the TE 22,6 mode but it decreases monotonically with increasing reflection, dropping to 200 kW at 33% reflection. Furthermore, at a reflection above 22%, a power modulation at 25 to 30 MHz is observed, independent of the phase of the reflected wave. Such a modulated signal may be useful in spectroscopic and other applications.

show abstract

“…frequency tunable double-disk FC75 face cooled sapphire window. The measured electronic efficiency of was 31 % (without depressed collector) [22]. High-power measurements of the output mode content using a 70 mm diameter wavenumber spectrometer (see Fig.…”

Section: Kit 500 Kw 140 Ghz Te104 Mode Gyrotron With Axial Outputmentioning

confidence: 99%

Gyro-devices – natural sources of high-power high-order angular momentum millimeter-wave beams

Thumm

2020

TST

Self Cite

View full text Add to dashboard Cite

The Orbital Angular Momentum (OAM) carried by light beams with helical phasefront (vortex beams) has been widely employed in many applications such as optical tweezers, optical drives of micro-machines, atom trapping, and optical communication. OAM provides an additional dimension (diversity) to multiplexing techniques, which can be utilized in addition to conventional multiplexing methods to achieve higher data rates in wireless communication. OAM beams have been thoroughly studied and used in the optical regime but in the mm-wave and THz-wave region, they are still under investigation. In these frequency bands, there are difficulties associated with beam-splitting and beam-combining processes as well as with the use of spiral phase plates and other methods for OAM generation, since the wavelength is much larger compared to those at optical frequencies, leading to higher diffraction losses. The present paper describes the natural generation of high-power OAM modes by gyro-type vacuum electron devices with cylindrical interaction circuit and axial output of the generated rotating higher-order transverse electric mode TEm,n, where m > 1 and n are the azimuthal and radial mode index, respectively. The ratio between the total angular momentum (TAM) JN and total energy WN of N photons is given by m/ω, where ω is the angular frequency of the operating mode, which in a gyrotron oscillator is close to the TEm,n-mode cutoff frequency in the cavity. Therefore, m/ω = Rc/c, where Rc is the caustic radius and c the velocity of light in vacuum. This means that the OAM is proportional to the caustic radius and at a given frequency the same for all modes with the same azimuthal index m. Right-hand rotation (co-rotation with the electrons) corresponds to a positive value of m and left-hand rotation to negative m. The corresponding OAM mode number (topological charge) is l = m – 1. Circularly polarized TE1n modes only possess a Spin Angular Momentum (SAM: s = ±1). TE0n modes have neither SAM nor OAM. This is the result of the photonic (quasi-optical) approach to derive the TAM of modes generated in gyrotrons. The same result follows from the electromagnetic (EM) wave approach for the TAM within a given waveguide volume per total energy of the EM wave in the same volume. Such high-power output beams with very pure higher-order OAM, generated by gyrotron oscillators or amplifiers (broadband) could be used for multiplexing in long-range wireless communications. The corresponding mode and helical wavefront sensitive detectors for selective OAM-mode sorting are available and described in the present paper.

show abstract

Experimental results and numerical simulations of a high power 140 GHz gyrotron

Cited by 31 publications

References 24 publications

CONCEPTUAL DESIGN STUDIES OF AN 84 GHz, 500 kW, CW GYROTRON

CONCEPTUAL DESIGN STUDIES OF AN 84 GHz, 500 kW, CW GYROTRON

Study of the Effect of Reflections on High-Power, 110-GHz Pulsed Gyrotron Operation

Gyro-devices – natural sources of high-power high-order angular momentum millimeter-wave beams

Contact Info

Product

Resources

About