Abstract
Linear induction accelerators used in X-ray radiography have single-pulse parameters of the order 20 MeV of electron beam energy, 2 kA of beam current, pulse lengths of 50-100 ns, and spot sizes of 1-2 mm. The thermal energy deposited in a bremsstrahlung converter target made of tantalum from such a pulse is ∼80 kJ/cc, more than enough to bring the target material to a partially ionized state. The tail end of a single beam pulse, or any subsequent pulse in a multi-pulse train, undergoes a number of interactions with the target that can affect beam transport and radiographic performance. Positive ions extracted from the target plasma by the electron beam space charge can affect the beam focus and centroid stability. As the target expands on the inter-pulse time scale, the integrated line density of material decreases, eventually affecting the X-ray output of the system. If the target plume becomes sufficiently large, beam transport through it is affected by macroscopic charge and current neutralization effects and microscopic beam/plasma instability mechanisms. We will present a survey of some of these interactions, as well as some results of an extensive experimental and theoretical campaign to understand the practical amelioration of these effects, carried out at the ETA-II accelerator facility at the Lawrence Livermore National Laboratory.
| Original language | English (US) |
|---|---|
| Title of host publication | Proceedings of the IEEE Particle Accelerator Conference |
| Editors | J. Chew, P. Lucas, S. Webber |
| Pages | 563-567 |
| Number of pages | 5 |
| Volume | 1 |
| State | Published - 2003 |
| Externally published | Yes |
| Event | PAC 2003 - Proceedings of the 2003 IEEE Particle Accelerator Conference - Portland, OR, United States Duration: May 12 2003 → May 16 2003 |
Other
| Other | PAC 2003 - Proceedings of the 2003 IEEE Particle Accelerator Conference |
|---|---|
| Country | United States |
| City | Portland, OR |
| Period | 5/12/03 → 5/16/03 |
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ASJC Scopus subject areas
- Engineering(all)
Cite this
Electron beam/converter target interactions in radiographic accelerators. / McCarrick, J.; Caporaso, George J; Chambers, F.; Chen, Y. J.; Falabella, S.; Goldin, F.; Guethlein, G.; Ho, D.; Richardson, R.; Weir, J.
Proceedings of the IEEE Particle Accelerator Conference. ed. / J. Chew; P. Lucas; S. Webber. Vol. 1 2003. p. 563-567.Research output: Chapter in Book/Report/Conference proceeding › Conference contribution
}
TY - GEN
T1 - Electron beam/converter target interactions in radiographic accelerators
AU - McCarrick, J.
AU - Caporaso, George J
AU - Chambers, F.
AU - Chen, Y. J.
AU - Falabella, S.
AU - Goldin, F.
AU - Guethlein, G.
AU - Ho, D.
AU - Richardson, R.
AU - Weir, J.
PY - 2003
Y1 - 2003
N2 - Linear induction accelerators used in X-ray radiography have single-pulse parameters of the order 20 MeV of electron beam energy, 2 kA of beam current, pulse lengths of 50-100 ns, and spot sizes of 1-2 mm. The thermal energy deposited in a bremsstrahlung converter target made of tantalum from such a pulse is ∼80 kJ/cc, more than enough to bring the target material to a partially ionized state. The tail end of a single beam pulse, or any subsequent pulse in a multi-pulse train, undergoes a number of interactions with the target that can affect beam transport and radiographic performance. Positive ions extracted from the target plasma by the electron beam space charge can affect the beam focus and centroid stability. As the target expands on the inter-pulse time scale, the integrated line density of material decreases, eventually affecting the X-ray output of the system. If the target plume becomes sufficiently large, beam transport through it is affected by macroscopic charge and current neutralization effects and microscopic beam/plasma instability mechanisms. We will present a survey of some of these interactions, as well as some results of an extensive experimental and theoretical campaign to understand the practical amelioration of these effects, carried out at the ETA-II accelerator facility at the Lawrence Livermore National Laboratory.
AB - Linear induction accelerators used in X-ray radiography have single-pulse parameters of the order 20 MeV of electron beam energy, 2 kA of beam current, pulse lengths of 50-100 ns, and spot sizes of 1-2 mm. The thermal energy deposited in a bremsstrahlung converter target made of tantalum from such a pulse is ∼80 kJ/cc, more than enough to bring the target material to a partially ionized state. The tail end of a single beam pulse, or any subsequent pulse in a multi-pulse train, undergoes a number of interactions with the target that can affect beam transport and radiographic performance. Positive ions extracted from the target plasma by the electron beam space charge can affect the beam focus and centroid stability. As the target expands on the inter-pulse time scale, the integrated line density of material decreases, eventually affecting the X-ray output of the system. If the target plume becomes sufficiently large, beam transport through it is affected by macroscopic charge and current neutralization effects and microscopic beam/plasma instability mechanisms. We will present a survey of some of these interactions, as well as some results of an extensive experimental and theoretical campaign to understand the practical amelioration of these effects, carried out at the ETA-II accelerator facility at the Lawrence Livermore National Laboratory.
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M3 - Conference contribution
AN - SCOPUS:4143086145
VL - 1
SP - 563
EP - 567
BT - Proceedings of the IEEE Particle Accelerator Conference
A2 - Chew, J.
A2 - Lucas, P.
A2 - Webber, S.
ER -