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Vacuum transmission lines for pulse sharpening and diagnostics applications

Description: We investigated the propagation of MV electrical pulses along coaxial transmission lines (TL) in vacuum with network simulations and experiments. One goal was to establish how well a 3 m-long TL would sharpen the output pulse of a relativistic electron beam accelerator. Sharpening occurs as the cathode of the TL emits electrons and the current flow forces the TL into magnetic cut-off. The other goal was to determine how well field emission must be suppressed in a TL to avoid distortion of a propagating pulse. Simulations predict a four-fold risetime improvement (8 ns to 2 ns) through magnetic insulation in a TL with an electrical length (10 ns) comparable to the risetime of the input pulse. In the laboratory we have shown a five-fold improvement (15 to 3 ns) with a velvet covered 3-m line and a 7.5 fold improvement (2 ns) when a vacuum flashover switch was incorporated between the first third and the last two thirds of the TL. Simple arguments and TL simulations suggest that even a small fraction (1 or 2%) of Child-Langmuir (CL) space charge limited emission will distort a propagating voltage pulse. This result is of particular importance when the TL is part of a voltage diagnostic system.
Date: June 1, 1987
Creator: Di Capua, M.S.; Goerz, D.A. & Freytag, E.K.
Partner: UNT Libraries Government Documents Department

Characterization of on-chip polycrystalline silicon photoconductors

Description: We report experimental and modeling studies of on-ship photoconductor pulse generation and sampling. Specifically, we discuss (a) the effect of ion-beam damage on carrier lifetime and sampling-aperture time, (b) the circuit limits to pulse risetime, and (c) the room-temperature stability of ion-beam-damaged sampling gates.
Date: January 1, 1986
Creator: Fitzpatrick, D.K.; Bowman, D.R. & Hammond, R.B.
Partner: UNT Libraries Government Documents Department

Quad nanosecond delay module

Description: Four nanosecond (ns) delay units have been designed to fit in a single-width NIM module. This module is particularly suited for use in conjunction with quad constant fraction timing discriminators (CFTDs) since it has four delay units that can be placed adjacent to the four units of the CFTD. A series of different length cables connected via DIP toggle switches provide delays of 0.60 ns in 4 ns increments. Thus, the CFTD delay can be optimized for pulses of different rise times from approx.10-100 ns. Design work for the PC board and silkscreening of the front panel were done with the MacDraw program on the Apple Mackintosh computer and printed with the Lasewriter printer. 6 refs.
Date: April 1, 1986
Creator: McDonald, R.J.; Hunter, J.B. & Wozniak, G.J.
Partner: UNT Libraries Government Documents Department

Discharge circuits and loads

Description: This will be an overview in which some of the general properties of loads are examined: their interface with the energy storage and switching devices; general problems encountered with different types of loads; how load behavior and fault modes can impact on the design of a power conditioning system (PCS).
Date: October 15, 1980
Creator: Sarjeant, W.J.
Partner: UNT Libraries Government Documents Department

Resolution limitations and optimization of the LLNL streak camera focus

Description: The RCA C73435 image tube is biased at voltages far from its original design in the LLNL ultrafast (10 ps) streak camera. Its output resolution at streak camera operating potentials has been measured as a function of input slit width, incident-light wavelength, and focus-grid voltage. The temporal resolution is insensitive to focus-grid voltage for a narrow (100 ..mu..m) input slit, but is very sensitive to focus-grid voltage for a wide (2 mm) input slit. At the optimum wide-slit focus voltage, temporal resolution is insensitive to slit width. Spatial resolution is nearly independent of focus-grid voltage for values that give good temporal resolution. Both temporal and spatial resolution depend on the incident-light wavelength. Data for 1.06-..mu..m light show significantly better focusing than for 0.53-..mu..m light. Streak camera operation is simulated with a computer program that calculates photoelectron trajectories. Electron ray tracing describes all of the observed effects of slit width, incident-light wavelength, and focus-grid voltage on output resolution. 7 refs.
Date: September 1, 1987
Creator: Lerche, R.A. & Griffith, R.L.
Partner: UNT Libraries Government Documents Department

Subnanosecond trigger system for ETA

Description: A high-voltage trigger system capable of triggering 30, 250 kV spark gaps; each with less than +- 1 ns jitter has been constructed. In addition to low jitter rates, the trigger system must be capable of delivering the high voltage pulses to the spark gaps either simultaneously or sequentially as determined by other system requirements. The trigger system consists of several stages of pulse amplification culminating in 160 kV pulses having 30 ns risetime. The trigger system is described and test data provided.
Date: May 30, 1980
Creator: Cook, E.G.; Lauer, E.J.; Reginato, L.L.; D., Rogers & Schmidt, J.A.
Partner: UNT Libraries Government Documents Department