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Plasma-filled focusing cell for radiographic paraxial diodes on RITS

Conference Record of the International Power Modulator Symposium and High Voltage Workshop

Hahn, K.; Maenchen, John E.; Cordova, S.; Molina, I.; Portillo, Salvador; Rovang, Dean C.; Schamiloglu, E.; Welch, D.R.; Oliver, B.V.; Rose, D.V.

Paraxial diodes have been a stronghold for high-brightness, flash x-ray radiography. In its traditional configuration, an electron beam impinges onto an anode foil, entering a gas-filled transport cell. Within the cell, the beam is focused into a small spot onto a high-Z target to generate x-rays for the radiographic utility. Simulations using Lsp, a particle-in-cell code, have shown that within the gas-filled focusing cell the electron beam spot location sweeps axially during the course of the beam pulse. The result is a larger radiographic spot than is desirable. Lsp has also shown that replacing the gas-filled cell with a fully ionized plasma on the order of 1016 cm-3 will prevent the spot from significant beam sweeping, thus resulting in a smaller, more stable radiographic spot size. Sandia National Laboratories (SNL) is developing a plasma-filled focusing cell for future paraxial diode experiments. A z-discharge in a hydrogen fill is used to generate a uniform, highly ionized plasma. Laser interferometry is the key diagnostic to determine electron density in a light lab setting and during future paraxial diode shots on SNL's RITS-3 accelerator. A time-resolved spot diagnostic will also be implemented during diode shots to measure the change in spot size during the course of the pulse. © 2004 IEEE.

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TYPE Conference YEAR 2004
ScopusOSTI

Advances in pulsed-power-driven radiography system design

Maenchen, John E.; Cordova, S.; Bohlken, Fawn A.; Hahn, Kelly D.; Jaramillo, Deanna M.; Molina, I.; Portillo, Salvador; Madrid, Elizabeth A.; Rovang, Dean C.; Sceiford, Matthew S.

Flash x-ray radiography has undergone a transformation in recent years with the resurgence of interest in compact, high intensity pulsed-power-driven electron beam sources. The radiographic requirements and the choice of a consistent x-ray source determine the accelerator parameters, which can be met by demonstrated Induction Voltage Adder technologies. This paper reviews the state of the art and the recent advances which have improved performance by over an order of magnitude in beam brightness and radiographic utility.

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TYPE Conference YEAR 2004
OSTI

RITS-3 self-break water switch maintenance

Portillo, Salvador; Hahn, Kelly D.; Molina, I.; Cordova, S.; Maenchen, John E.

The radiographic integrated test stand (RITS-3) is a 5-MV, 160-kA, 70-ns inductive voltage adder accelerator at Sandia National Laboratories used to develop critical understanding of x-ray sources and flash radiographic drivers. On RITS-3 three pulse forming lines (PFLs) are used to drive three inductive voltage adder cavities. Each PFL contains a fast-pulse-charged, self-breakdown annular water switch that is used for initial pulse shaping and timing. Low loss in the switches combined with good synchronization is required for efficient operation of the accelerator. Switch maintenance is closely monitored over time to determine the effects of wear on switch breakdown performance.

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TYPE Conference YEAR 2004
OSTI

Retrapping studies on RITS

Hahn, Kelly D.; Welch, Dale R.; Johnson, David L.; Schamiloglu, E.; Maenchen, John E.; Cordova, S.; Molina, I.; Portillo, Salvador; Rovang, Dean C.; Oliver, Bryan V.

SNL is developing intense sources for flash x-ray radiography. The goals of the experiments presented here were to assess power flow issues and to help benchmark the LSP particle-in-cell code used to design the experiment. Comparisons between LSP simulations and experimental data are presented.

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TYPE Conference YEAR 2003
OSTI
Results 26–45 of 45
Results 26–45 of 45