The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
We present the observation, for the first time, of large, regular arrays of plasma filaments during surface and volume breakdown in air at atmospheric pressure using a focused, linearly polarized Gaussian output beam of a pulsed gyrotron. Both volume breakdown in free space and surface breakdown at/near a dielectric window have been studied. A gyrotron with an internal mode converter that emits 110...
Gyrotrons operating in the millimeter and submillimeter wavelength ranges are the promising sources for applications that are requiring good spectral characteristics and a wide range of output power. We report the precise measurement results of gyrotron spectra. Experiments were conducted using a 140-GHz long-pulse gyrotron that is developed for the dynamic nuclear polarization/nuclear-magnetic-resonance...
The initial experimental results of a zero-drive stable, short pulse 140 GHz gyro-traveling wave tube amplifier are presented. The amplifier has achieved a linear gain of 31 dB in experiment, and peak output powers up to 400 W have been observed at a beam voltage of 39.5 kV, beam current of 1.65 A, and beam pitch factor of 0.9 from a novel high order HE(0,6) operating mode of a quasi-optical confocal...
A single-stage depressed collector has been installed on a 1.5 MW, 110 GHz gyrotron and tested in 3 microsecond pulse operation at 96 kV and 40 A. The overall efficiency with the depressed collector was 50 % at 1.5 MW of output power with a voltage depression of 25 kV. Theory predicts up to 35 kV of depressed voltage for these operating conditions. The discrepancy between the experiment and the theory...
An internal mode converter with an axially studied cavity (V-2005) has been installed and successfully tested for the 110 GHz, 1.5 MW gyrotron at MIT. A good Gaussian beam was observed with an output power of 1.5 MW, operating at beam voltage of 96.6 kV and current of 42 A. The Gaussian beam waist was determined, and was found to be in good agreement with the designed value. Single-stage depressed...
We report the observation of low-frequency parasitic oscillations, near 100 MHz, in a 1.5 MW, 110 GHz gyrotron operating in 3 microsecond pulses at MIT. The oscillations were measured on capacitive probes, which are located near the microwave resonator and are ordinarily used to measure the beam velocity pitch factor. The dependence of the frequency of oscillation on beam current, voltage, and magnetic...
In summary, computer-controlled stable operation of a 0.46 THz CW gyrotron oscillator has successfully been demonstrated for 24 hours yielding great power stability, which is a major advance in proving the unique capability of gyrotrons for many kinds of applications requiring a few watts of CW power, such as imaging and medical therapy at submillimeter wavelength. Especially, this technology should...
Recently, an internal mode converter system has been installed in a 1.5 MW, 110 GHz gyrotron at MIT. We achieved an output power of 1.5 MW, corresponding to an efficiency of 37 % at a beam voltage of 96.6 kV and a beam current of 42 A. A Gaussian output beam was measured and the beam waist was determined. The depressed collector has been also setup. With a depressed collector, the efficiency was 50...
The design and simulation results for a 1 kW, 140 GHz gyro-amplifier are presented. A bandwidth of over 4.5 GHz has been achieved in simulation with peak saturated gain of over 52 dB. The HE 06 mode of a confocal cylindrical waveguide is chosen as the operating mode and distributed loss is employed via diffraction to stabilize the circuit. The amplifier will be capable of amplifying short pulses on...
Summary form only given. Recently, the 1.5 MW, 110 GHz gyrotron with a new cavity has been tested at MIT. The new cavity (V-2005) significantly reduces ohmic loss and, therefore, it is very promising for CW operation of a gyrotron. The gyrotron with the new cavity has been tested in the axial configuration. The maximum power is 1.67 MW in the design mode TE22,6, and the corresponding efficiency is...
Summary form only given. We present results of emission non-uniformity studies by 3D modeling and experiments on a 96 kV, 40 A magnetron injection gun (MIG) for use in a 1.5 MW 110 GHz gyrotron. Non-uniform beam current density is attributed to emitter surface roughness, surface temperature inhomogeneity, and variation of the work function along the emitting cathode ring. The emission nonuniformity...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.