نتایج جستجو برای: space charge
تعداد نتایج: 625441 فیلتر نتایج به سال:
Commonly, thermally activated delayed fluorescence (TADF) emitters present a twisted donor–acceptor structure. Here, electronic communication is mediated through-bond via π-conjugation between donor and acceptor groups. A second class of TADF are those where moieties through-space. In these through-space charge-transfer (TSCT) architectures, the groups disposed in pseudocofacial orientation lin...
Cellulose insulation polymer (paper/pressboard) has been widely used in high voltage direct current (HVDC) transformers. One of the most challenging issues in the insulation material used for HVDC equipment is the space charge accumulation. Effective ways to suppress the space charge injection/accumulation in insulation material is currently a popular research topic. In this study, an aluminium...
Low energy beam transport (LEBT) for a future heavy ion driven inertial fusion (HIDIF [1]) facility is a crucial point using a Bi beam of 40 mA at 156 keV. High space charge forces (generalised perveance K=3.6*10) restrict the use of electrostatic focussing systems. On the other hand magnetic lenses using space charge compensation suffer from the low particle velocity. Additionally the emittanc...
Time-resolved hard X-ray photoelectron spectroscopy (trHAXPES) using microfocused X-ray free-electron laser (XFEL, hν = 8 keV) pulses as a probe and infrared laser pulses (hν = 1.55 eV) as a pump is employed to determine intrinsic charge-carrier recombination dynamics in La:SrTiO3. By means of a combination of experiments and numerical N-body simulations, we first develop a simple approach to c...
We present a comparison between space charge calculations and direct measurements of the transverse phase space of space charge dominated electron bunches from a high voltage dc photoemission gun followed by an emittance compensation solenoid magnet. The measurements were performed using a double-slit emittance measurement system over a range of bunch charge and solenoid current values. The dat...
Title of Document: LONGITUDINAL SPACE-CHARGE WAVES INDUCED BY ENERGY MODULATIONS Brian L. Beaudoin, Master of Science, 2008 Directed By: Professor Patrick G. O’Shea and Professor Rami A. Kishek Department of Electrical and Computer Engineering High intensity beams that are space-charge dominated are important for applications such as free electron lasers that require high intensity and low emit...
Method of calculation of space charge field of the beam using an expansion of space charge potential and space charge distribution as Fourier-Bessel series is discussed. Coefficients of series are connected by an algebraic equation, which substantially simplifies solution of the problem. Efficiency and accuracy of the method are discussed. Suggested method is effective in multidimensional probl...
We report on a new experimental study of the space charge effect in a space-charge-dominated multi-beam electron bunch. A 5 MeV electron bunch, consisting of a variable number of beamlets separated transversely, was generated in a photoinjector and propagated in a drift space. The collective interaction of these beamlets was studied for different experimental conditions. The experiment allowed ...
The transverse dynamics of space-charge dominated beams are investigated both analytically and computationally, in order to understand the mechanisms for emittance oscillations and growth due to nonlinear space-charge fields. This work explores the role of space-charge dominated equilibrium and its relationship to phase space wave breaking, which is responsible for the irreversible emittance gr...
Ultrahigh spectral brightness femtosecond XUV and X-ray sources like free electron lasers (FEL) and table-top high harmonics sources (HHG) offer fascinating experimental possibilities for analysis of transient states and ultrafast electron dynamics. For electron spectroscopy experiments using illumination from such sources, the ultrashort high-charge electron bunches experience strong space-cha...
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