Charge per pulse

At ELYSE, the intensity and position of the electron beam is observed upstream of each experimental area by wall current monitors. Ceramic screens are used to indicate the transverse beam profile. The charge per pulse is measured by a moveable Faraday cup. The charge extracted from the CsjTe photo-cathode is 1-8 nC, with a linear slope of 7] = 0.25% electron per 263 nm photon absorbed at laser pulse energies up to 4 pj. At higher laser pulse energies, the current... 

Still increases but the quantum efficiency decreases due to the loss of part of the charge by recombination, up to a saturation level. Moreover, the electron repulsion increases with the charge per pulse and the pulse width becomes longer. 

Access to subpicosecond electron pulses has already been achieved at Osaka University by a new double-decker accelerator concept. In order to reduce the time jitter for the detection of the optical absorption signals in pulse radiolysis studies, the light pulse used for the pump-probe system is Cerenkov emission which is produced in the same cell by a synchronized second electron beam and is concomitant with the electron path. The distance between the axes of the two beams is 1.6 mm. The pulse durations of these electron pulses, which are both produced by delayed beams issued from the same laser, are 430 + 25 fs and 510 20 fs, respectively, and the charge per pulse is 0.65 nC. An electron bunch of 100 fs and 0.17 nC has already been generated. 

The basic operation of a rate meter is to feed a known charge per pulse into a capacitor that is shunted by a resistor (Fig. 5.28). Let... 

Fig. 14 Charge (Q) ys. Charge Density (Q/A) for Safe Stimulation A microelectrode with relatively small total charge per pulse might safely stimulate using a laige charge density, whereas a large surface area electrode (with greater total chaige per pulse) must use a lower charge density...

Efficacy requires that the charge injected must exceed some threshold (Fig. 13). However, as the charge per pulse increases, the overpotential of the electrode... 

Three types of measurements were performed in this study. First, photodissociation cross sections were measured, in which the total photofragment yield was measured as a function of dissociation photon energy. In these experiments, the electron signal generated by the microchannel plates is collected with a flat metal anode, so that only the total charge per laser pulse is measured. The beam block is 3 mm wide for these measurements. 

Fig. 3 a and b. Pulse height (normaUzed to low rate pulse height) versus count rate per anode wire length. Parameter the number of charges per avalanche, a Standard proportional counter b Optimized high rate counter (From Ref. )... 

Incidence of compression plasma flow on the silicon surface causes a shock-compressed plasma layer to form. The energy absorbed by silicon depending on the sample location ranges from 5 to 25 J per pulse, which corresponds (in our experimental conditions) to an increase in power density of plasma flow from 0.510 to 310 W/cm. In its turn, the density of charged particles in plasma varies from 10 cm at the maximum contraction to lO cm in the area of compression flow divergence. Under these conditions, the impact pressure developed by incident plasma flow on the silicon surface ranged from 10 to 30 bar. 

Unrecoverable Charge (Qur) per pulse = Injected Charge (Ginj) per pulse (31)... 

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