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New trends of gyrotron development at KIT: An overview on recent investigations
摘要： Since many years KIT is strongly involved in the development of high power gyrotrons for use in ECRH. KIT is pursuing two development lines: (i) the conventional, hollow cavity gyrotron and (ii) the coaxial cavity gyrotron. KIT is pushing conventional cavity gyrotrons from 1 MW to 1.5 MW in a common project with IPP Greifswald. Coaxial cavity technology having the advantage of higher power capability, in particular at higher frequency, is used for the 2 MW 170 GHz short-pulse prototype. This gyrotron is currently being upgraded to allow pulse extension up to approximately 100 ms and up to 1 s in a second step. For a future DEMOnstration fusion power plant two challenging trends with respect to gyrotron features are recognized: (a) the operating frequency will be above 200 GHz and (b) the requested total efficiency of the gyrotron should be higher than 60%. KIT is addressing these requirements by investigating both gyrotron technologies for their performance at a frequency well above 200 GHz. We started careful analysis of multi-staged-depressed collectors.
关键词： Electron-cyclotron-resonance heating and current drive,Gyrotron,Coaxial cavity,Magnetron injection gun
更新于2025-09-23 15:23:52
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The Temperature Dependences of the Electron-Piezoelectric Potential Phonon Interacting System of Quasi Two Dimensional System in GaN and ZnS
摘要： We investigated theoretically the temperature dependence of the quantum optical transition of quasi 2-Dimensional Landau splitting system, in GaN and ZnS. We apply the Quantum Transport theory (QTR) to the system in the con?nement of electrons by square well con?nement potential. We use the projected Liouville equation method with Equilibrium Average Projection Scheme (EAPS). Through the analysis of this work, we found the increasing properties of Quantum Transition Line Shapes (QTLSs) and the Quantum Transition Line Widths (QTLWs) of CdS and GaN with the temperature we also found that QTLW, (cid:2)(cid:3)T (cid:4) of ZnS < (cid:2)(cid:3)T (cid:4) of GaN in (cid:5) = 394 (cid:6)m.
关键词： Quantum Transport Theory,Quantum Transition Line Widths (QTLW),Quantum Transition Line Shapes (QTLS),GaN and ZnS,Cyclotron Resonance,Equilibrium Average Projection Scheme (EAPS),Electron Phonon Coupling System
更新于2025-09-23 15:22:29
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Characterization of ECR plasma by means of radial and axial X-ray diagnostics
摘要： This work presents the X-ray characterization of the plasma generated in a simple mirror axis symmetric trap as a function of the magnetic field profile. A Si-Pin detector has been used to characterize warm electron population in axial and radial directions at 6.83 GHz. Moreover, the hot electrons emitted in axial direction has been measured by means of a HyperPure Germanium (HpGe) detector. Results show that X-ray emission is not homogenous, and its homogeneity and temperature depend strongly on the magnetic field profile, and especially on the Bmin/BECR ratio.
关键词： Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS)),Solid state detectors,X-ray detectors
更新于2025-09-23 15:22:29
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Nonlinear Cyclotron Resonance Absorber for a Microwave Subnanosecond Pulse Generator Powered by a Helical-Waveguide Gyrotron Traveling-Wave Tube
摘要： A well-known principle for periodical production of high-power ultrashort optical pulses is related to passive mode locking realized when a saturable absorber is incorporated into the laser resonator. A similar effect can be implemented in two-section electronic oscillators comprising an amplifier and a saturable absorber, which should be applicable in the microwave frequency band and suitable for high-power operation. In this paper, we analyze in detail the possibility of realizing a saturable absorber based on cyclotron resonance interaction in the regular waveguide with initially rectilinear electron beam, when saturation is caused by the relativistic dependence of the gyrofrequency on electron energy. Maximum contrast between the absorption of a high-power signal and of a weak signal is achieved in the group synchronism regime when the particle velocity is close to the wave’s group velocity. Within the frame of a time-domain self-consistent model, we demonstrate that when such an absorber is installed in the feedback loop of an electron generator powered by existing Ka-band helical-waveguide gyrotron traveling-wave tube, periodical generation of subnanosecond pulses can be provided with peak power up to several hundred kW and sub-GHz repetition frequency. We discuss the influence of deviation from the group synchronism regime on the parameters of generated pulses. Experimental feasibility of the considered scheme is verified based on three-dimensional particle-in-cell simulations.
关键词： gyrotron traveling-wave tube,cyclotron resonance,subnanosecond pulse,saturable absorber,microwave
更新于2025-09-23 15:19:57
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Introduction to Quantum Electronics and Nonlinear Optics || Field Interaction with a??Free Chargesa??
摘要： The chapter discusses the interaction of electromagnetic fields with 'free charges' in plasma, focusing on the kinetic equation, cyclotron resonance, and fundamental absorption in semiconductors. It explores the classical and quantum mechanical descriptions of plasma behavior under external fields, including the effects of magnetic fields on electron motion and the absorption of electromagnetic waves by semiconductors.
关键词： semiconductors,plasma,cyclotron resonance,electromagnetic fields,free charges,kinetic equation,fundamental absorption
更新于2025-09-23 15:19:57
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Proton beams of laser-hydrogenated metal targets
摘要： In this paper, we report a study on proton beams produced via laser interaction from hydrogenated solid targets useful for the development of new sources devoted to medical applications, such as hadron therapy and isotope production. The hydrogenation of the targets was made before the laser-matter interaction. In this study, we used as solid targets, pure samples of Ti, Ta and Al which in a ?rst phase were treated by laser cleaning (via KrF excimer laser at the irradiance I = 3×107 W/cm2) and then they were exposed to laser irradiation (1500 pulses, I = 3×107 W/cm2) under a constant ?ow of H2 (HiQ Hydrogen 6.0, highly pure). After that, the targets were maintained under H2 ?ow for 5 minutes, in order to promote a further hydrogen adsorption. We report laser ablation measurements performed at ?uences of 1.3, 2.5 and 5.0 J/cm2. The results on hydrogenated targets showed an increase of proton yield of 25% (Ti), 64% (Al) and 550% (Ta), with respect to the corresponding untreated ones.
关键词： Plasma generation (laser-produced, RF, x ray-produced),Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS)),Accelerator Applications
更新于2025-09-19 17:13:59
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Laser absorption spectroscopy studies to characterize Cs oven performances for the negative ion source SPIDER
摘要： The SPIDER H?/D? ion source is currently in operation in the Neutral Beam Test facility (NBTF) at Consorzio RFX (Padova, Italy) to prove the possibility of generating up to 40 A of negative ions, with a maximum extracted current density of 350 A/m2 (H)/285 A/m2 (D) and a fraction of co-extracted electrons not greater than 0.5 (H)/1 (D). These performances are required for the realization of the ITER Neutral Beam Injector (NBI), which should deliver 16.7 MW to the plasma by means of negative ions accelerated up to 1 MeV and neutralized before being injected into the ITER tokamak. In order to obtain such high extracted current densities and low co-extracted electron fractions it is necessary to lower the work function of the surface of the acceleration system grid facing the source; this will be accomplished by coating the surfaces with Cs, routinely evaporated by three ovens. The functionality of the ovens has been tested at the CAesium oven Test Stand (CATS), hosted at NBTF. The test stand is equipped with several diagnostics, among which a Laser Absorption Spectroscopy (LAS) diagnostic. Using a tunable laser diode, the LAS diagnostic gets the high resolution absorption spectrum of the Cs 852 nm D2 line along a line of sight to measure Cs density at ground state. The paper describes the test stand and the LAS diagnostic, together with the characterization of the ovens to be installed in SPIDER. The paper will also study the systematic density underestimation e?ect caused by Cs ground state depopulation, as a function of laser intensity and of Cs density, in the perspective of correcting the density evaluation.
关键词： Plasma diagnostics - interferometry, spectroscopy and imaging,Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS))
更新于2025-09-16 10:30:52
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Fundamentals and Applications of Fourier Transform Mass Spectrometry || Fourier transform ion cyclotron resonance mass spectrometry and laser: A versatile tool
摘要： The coupling of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with laser combines the attributes of laser mass spectrometry with the analytical capabilities of a mass spectrometer having high resolution, high mass measurement accuracy, long ion-observation times, and exceptional ion isolation capabilities required for ion-molecule reaction or ion fragmentation studies [1–3]. The laser may be used for different purposes in mass spectrometry. The most standard one is to generate ions from the surface of the laser-irradiated sample. Two regimes have to be considered in respect with the laser fluence (energy deposit per surface unit in J/cm2) or the laser power density also named irradiance (power density deposit per surface unit in W/cm2). At low laser fluence, laser desorption/ionization (LDI) may take place. When the laser fluence increases, the regime of laser–matter interaction is modified and laser ablation (LA) occurs. In both cases, the ionization phenomenon and the transfer of the atoms or molecules to the gas phase are the direct result of the laser matter interaction. LDI and LA are well suited to the analysis of a wide range of organic, inorganic and also biological compounds. For complex matrices, it is important to note that information may be obtained on both organic and inorganic species. This is of first importance for the study of environmental or composite samples for example, in which organics, inorganics and/or polymers are intimately associated.
关键词： laser,Fourier transform ion cyclotron resonance mass spectrometry,laser desorption/ionization,organic compounds,mass spectrometry imaging,inorganic compounds,laser ablation
更新于2025-09-16 10:30:52
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Protein profiling analysis based on matrix-assisted laser desorption/ionization-Fourier transform ion cyclotron resonance mass spectrometry and its application in typing Streptomyces isolates
摘要： Marine Streptomyces is a potential source of novel bioactive natural products in medicine and agriculture. The current discrimination and screening method of Streptomyces isolates is not accurate and time-consuming, and a novel method is necessary. In this study, a protein profiling method based on an ultrahigh resolution 15 Tesla Matrix-assisted laser desorption/ionization-Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR MS) was established and applied for differentiation and bioactivity screening of marine Streptomyces isolates. To obtain robust protein profiling, the effects of the protein extraction method, the matrix-solvent, the sample deposition mode, and the culture time of isolates on protein profiling were thoroughly studied, the optimal conditions were obtained. To evaluate the performance of the developed MALDI-FTICR MS method, MALDI-time of flight (TOF) MS and 16S rRNA were applied in parallel to analyze 25 marine Streptomyces isolates. We found that the clustering result of MALDI-FTICR MS was more similar to that of 16S rRNA than MALDI-TOF MS. And MALDI-FTICR MS could effectively indicate the antibacterial activity of Streptomyces isolates against three plant pathogenic bacteria including Xanthomonas campestris, Xanthomonas oryzae and Erwinia carotovora. Furthermore, a differential protein/peptide was defined and successfully applied to predict antibacterial activity of blind samples. This study demonstrated that MALDI-FTICR MS has great potential to discriminate and screen complex microorganisms, especially those closely related strains.
关键词： Protein profiling,Streptomyces isolates,Cluster analysis,Activity screening,Matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry
更新于2025-09-16 10:30:52
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Multi-diagnostic setup to investigate the two-close-frequency phenomena
摘要： While the mechanism is still not fully clear, the beneficial effect (higher intensity of highly charged ions, stable plasma conditions) of the second microwave injected to the ECR plasma was observed in many laboratories, both with close and far frequencies. Due to the complexity of the phenomena (e.g. interaction of resonant zones, damped instabilities) complex diagnostic methods are demanded to understand its mechanism better and to fully exploit the potential hidden in it. It is a challenging task since complex diagnostics methods require the arsenal of diagnostic tools to be installed to a relatively small size plasma chamber. Effect of the injected second 13.6–14.6 GHz microwave to the 14.25 GHz basic plasma has been investigated by means of soft and (time-resolved) hard X-ray spectroscopy, by X-ray imaging and space-resolved spectroscopy and by probing the rf signals emitted by the plasma. Concerning the characterization of the X radiation, in order to separate the source and position of different X-ray photons special metallic materials for the main parts of the plasma chamber were chosen. A detailed description and explanation of the full experimental setup and the applied non-invasive diagnostics tools and its roles are presented in this paper.
关键词： Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS)),X-ray detectors,Plasma diagnostics - interferometry, spectroscopy and imaging,Plasma generation (laser-produced, RF, x ray-produced)
更新于2025-09-09 09:28:46