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A commercially available electromagnetic simulator--MAGIC, a particle-in-cell (PIC) code--has been used to carry out a comparative study of the beam-wave interaction under uniform and tapered magnetic field profiles of a 42 GHz, 200kW gyrotron. The magnetic field profile across the resonant cavity varies by ±6.5% with a peak value of 1.615 T. The MAGIC simulation shows the desire performance of the gyrotron under both magnetic field conditions with an operating mode TE03 and a pitch factor of 1.26. The analysis of the simulated results show that stability in the power growth was reached more quickly and achieved higher output power in the case of a tapered magnetic field. PACS Nos: 07.57.Hm, 41.20.Jb Le simulateur eelectromagneetique MAGIC commercialement disponible est un code source de type PIC que nous avons utilise pour faire une etude comparee de l'interaction faisceau-onde sous champ magnetique uniforme et decroissant d'un gyrotron de 200 kW et 42 GHz. Le profil du champ magnetique dans la cavite resonante varie de [+ o -]6.5% avec une valeur pic de 1.615 T. La simulation MAGIC montre la performance deesireee du gyrotron sous les deux configurations magnetiques avec un mode TE03 d'utilisation et un coefficient de variation de 1.26. L'analyse des simulations montre que la stabilite de la montee en puissance est atteinte plus rapidement avec un profil de champ magnetique decroissant, qui permet aussi une plus grande puissance de sortie. [Traduit par la Redaction], 1. Introduction A gyrotron, based on the electron cyclotron maser (ECM) phenomenon, is a fast-wave device designed to produce high-power coherent millimetre and submillimeter wavelength radiation [1, 2]. In a [...]

A 42-GHz, 200-kW gyrotron was developed and tested for the Indian plasma fusion system. The gyrotron was designed for the TE0,3 operating mode. The configuration of the triode-type magnetron injection gun (MIG) with the linear RF output, undepressed collector, and face-cooled double disk window was adopted in this gyrotron because of the first development experience. The complete tube was developed and processed at Central Electronics Engineering Research Institute (CEERI), Pilani, India. The RF testing of the gyrotron was performed at the participating institute, Institute of Plasma Research (IPR), Gandhinagar, India. Due to some cooling issues in the collector region, the tube was tested by a resistive capacitor network-based power supply for a very short pulse in place of a long pulse, high voltage power supply. The tube was tested up to the beam voltage of 51 kV and a beam current of 12 A at the cavity magnetic field of 1.61 T for the short pulse of $500~\mu \text{s}$. The tube was inserted into the magnet system consisting of a main electromagnet, auxiliary gun coils, and collector magnets. The multi-hole and single hole couplers were used to measure the RF power in the TE0,3 mode and the overall power, respectively. The measured results were also compared with the simulated results and a close agreement of the results was found. The short pulse testing confirms the electrical design and the development approach for the 42-GHz gyrotron tube. [ABSTRACT FROM AUTHOR]

Context: Eucalyptus camaldulensis Dehnh. (Myrtaceae) is a tall evergreen tree found commonly in Bangladesh. Its use in traditional folk medicine for the treatment of various health complications are well known. Objective: To explore the in vivo antitumor effect of Eucalyptus camaldulensis stem bark methanol extract (ME) against Ehrlich's ascites carcinoma (EAC) in Swiss albino mice. Materials and methods: The antitumor activity of ME was studied by determining viable tumor cell count, recording tumor weight and survival time, observing morphological changes and nuclear damage of EAC cells, and estimating hematological as well as biochemical parameters of experimental mice (25, 50 and 100 mg/kg/day for 5 d, i.p.). Results: ME showed 96% ( p < 0.001) cell growth inhibition and reduced tumor burden significantly (81.4%; p < 0.01) when compared with control mice. It also increased the lifespan of EAC-bearing mice significantly (71.36%; p < 0.01). It also restored the altered hematological and biochemical parameters towards normal level. The high LD50 value (1120 mg/kg) of ME indicated its low host toxic effects. ME-treated EAC cells showed membrane blebbing, chromatin condensation, nuclear fragmentation (apoptotic features) in Hoechst 33342 staining under fluorescence microscope. The DNA profile in agarose gel (1.5%) electrophoresis also confirmed that ME caused EAC cell death by apoptosis. Discussion and conclusion: Results showed that ME exhibits strong anticancer activity through apoptosis and stimulation of host immunity. Thus, E. camaldulensis may be considered as a promising resource in cancer chemotherapy. [ABSTRACT FROM AUTHOR]