A New Lumped Approach for the Simulation of the Magnetron Injection Gun for MegaWatt-Class EU Gyrotrons

In the framework of the ITER (International Thermonuclear Experimental Reactor) project, one of the key components of the reactor is the ECRH (Electron Cyclotron Resonance Heating). This system has the duty to heat the plasma inside the tokamak, using high frequency and power radio waves, produced by sets of 1MW gyrotrons. One of the main issues related to the gyrotron operation is the output power drop that happens right after the beginning of a pulse. In this work, we study the underlying phenomena that cause the power drop, focusing on the gyrotron’s MIG (Magnetron Injection Gun) of the 1MW, 170 GHz European Gyrotron prototype for ITER. It is shown how the current emission and the temperature of the emitter are tightly bound, and how their interaction causes the power drop, observed experimentally. Furthermore, a simple yet effective lumped-parameter model to describe the MIG’s cathode thermal dynamics is developed, which is able to predict the power output of the gyrotron by simulating the propagation of the heat inside this component. The model is validated against test results, showing a good capability to reproduce the measured behavior of the system, while still being open to further improvements.

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Dynamic Stability of a Water Brake Dynamometer

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2818092 ◽

1998 ◽

Vol 120 (1) ◽

pp. 89-96 ◽

Cited By ~ 1

Author(s):

R. A. Van den Braembussche ◽

H. Malys

Keyword(s):

High Frequency ◽

Low Frequency ◽

Lumped Parameter Model ◽

Stable Operation ◽

Pressure Oscillations ◽

Lumped Parameter ◽

Flow Oscillations ◽

Brake Dynamometer ◽

Low Torque ◽

Frequency Variations

A lumped parameter model to predict the high frequency pressure oscillations observed in a water brake dynamometer is presented. It explains how the measured low frequency variations of the torque are a consequence of the variation in amplitude of the high frequency flow oscillations. Based on this model, geometrical modifications were defined, aiming to suppress the oscillations while maintaining mechanical integrity of the device. An experimental verification demonstrated the validity of the model and showed a very stable operation of the modified dynamometer even at very low torque.

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A Simple Dynamic Modeling of Head Slap in Hard Disk Drive

Volume 6B: 18th Biennial Conference on Mechanical Vibration and Noise ◽

10.1115/detc2001/vib-21503 ◽

2001 ◽

Author(s):

Seong-Hun Lee ◽

Jeong-Hak Lee ◽

Kwang-Joon Kim

Keyword(s):

Hard Disk Drive ◽

Dynamic Modeling ◽

Structural Design ◽

Continuous System ◽

Disk Drive ◽

Lumped Parameter Model ◽

Test Results ◽

Lumped Parameter ◽

Shock Resistance ◽

The Impact

Abstract In order to understand mechanism of the impact between head and disk of a HDD subject to a shock and to improve the shock resistance effectively, it is essential to develop a dynamic model which can represent well the head slap. Although motion of the head and disk subject to a shock requires modeling by a continuous system to be rigorous, in this study, a simplified lumped parameter model is developed to understand basic dynamics of the head slap and to determine crucial parameters for the improvement of the structural design. In addition, drop test results of the HDD are presented to back to up the derived model.

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Transformer high frequency modelling based on lumped parameter model by consideration of corelosses

2014 22nd Iranian Conference on Electrical Engineering (ICEE) ◽

10.1109/iraniancee.2014.6999639 ◽

2014 ◽

Author(s):

Reza Zeinali ◽

Ahmad Javid Ghanizadeh ◽

Rasul Tarvirdilu Asl ◽

Gevorg B. Gharehpetian

Keyword(s):

High Frequency ◽

Lumped Parameter Model ◽

Lumped Parameter

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Modified Earpieces and CROS for High Frequency Hearing Losses

Journal of Speech and Hearing Research ◽

10.1044/jshr.1101.204 ◽

1968 ◽

Vol 11 (1) ◽

pp. 204-218 ◽

Cited By ~ 9

Author(s):

Elizabeth Dodds ◽

Earl Harford

Keyword(s):

Hearing Loss ◽

Hearing Aids ◽

High Frequency ◽

Hearing Aid ◽

Sound Field ◽

Intensity Level ◽

Test Results ◽

High Frequency Hearing Loss ◽

Increased Sensitivity ◽

Difficult Cases

Persons with a high frequency hearing loss are difficult cases for whom to find suitable amplification. We have experienced some success with this problem in our Hearing Clinics using a specially designed earmold with a hearing aid. Thirty-five cases with high frequency hearing losses were selected from our clinical files for analysis of test results using standard, vented, and open earpieces. A statistical analysis of test results revealed that PB scores in sound field, using an average conversational intensity level (70 dB SPL), were enhanced when utilizing any one of the three earmolds. This result was due undoubtedly to increased sensitivity provided by the hearing aid. Only the open earmold used with a CROS hearing aid resulted in a significant improvement in discrimination when compared with the group’s unaided PB score under earphones or when comparing inter-earmold scores. These findings suggest that the inclusion of the open earmold with a CROS aid in the audiologist’s armamentarium should increase his flexibility in selecting hearing aids for persons with a high frequency hearing loss.

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