-
[show abstract]
[hide abstract]
ABSTRACT: In the PIM pulsed power machine a 1.5 MV, 100 ns duration pulse is generated by a 10 Ohm water Blumlein A prepulse reduction system based on a gas switch has been designed and built by Titan PSD. This has been fitted and reduced the prepulse to less than 3 kV. Prepulse of this order is necessary to drive the focused e-beam diodes used for flash radiography. Details of the prepulse reduction system, the experimental data obtained and comparison with computer models of the machine will be presented.
Pulsed Power Conference, 2005 IEEE; 07/2005
-
S.G. Clough,
K.J. Thomas,
M.C. Williamson,
M.J. Philips,
M.A. Sinclair,
I.D. Smith, V.L. Bailey,
P.A. Corcoran,
H. Kishi,
D.L. Johnson,
J.E. Maenchen
[show abstract]
[hide abstract]
ABSTRACT: The PIM machine has been designed and constructed at AWE to develop IVA technology for flash radiography of hydrodynamic experiments. While it was originally conceived as one module of a ten module, 14 MV, 100 kA machine versions operating at up to 3 MV are of interest to satisfy future radiographic applications at AWE. The IVA architecture will enable these machines to be relatively easily configurable in either negative or positive polarity allowing the diode to be either the self magnetic pinch type already in use at AWE or a rod pinch diode to achieve smaller radiographic spots. A Marx generator drives a 1.7 MV, 10 ohm water Blumlein initiated by twin radial laser triggered switches. The Blumlein has been used to drive either one or two parallel inductive cavities to obtain an output of 1.5 or 3 MV with a current of up to ∼150 kA or >50 kA respectively. Prepulse suppression is provided by a gas prepulse switch in the coaxial oil feed from the Blumlein to the cell or cells. The latest results of the testing of the laser triggering system and the prepulse reduction system will be presented.
Pulsed Power Conference, 2003. Digest of Technical Papers. PPC-2003. 14th IEEE International; 07/2003
-
V.L. Bailey,
L. Johnson,
P. Corcoran,
I. Smith,
J.E. Maenchen,
I. Molina,
K. Hahn,
D. Rovang,
S. Portillo,
B.V. Oliver,
D. Rose,
D. Welsh,
D. Droemer,
T. Guy
[show abstract]
[hide abstract]
ABSTRACT: RITS-3 is the three-cell, 4 MV, 156 kA, 70 ns embodiment of the full twelve-cell 16 MV Radiographic Integrated Test Stand (RITS) (Ian D. Smith et al., 2000). The well-instrumented RITS-3 experiments (David L. Johnson et al., 2002) now underway at Sandia are intended to investigate/validate critical design issues for scaling to RITS. These experiments use a magnetically-insulated transmission line (MITL) in which the increment in the operating impedance of the MITL from cell to cell is equal to the impedance of the individual pulse forming line (pfl)/induction cell (8 ohms). The matched load voltage that is obtained in this configuration is 4.0 MV and occurs when the load impedance equals the sum of the PFL impedances (24 ohms). This paper discusses the design of a higher impedance MITL intended to increase the RITS-3 output voltage from 4 MV to 5.25 MV for the same pulse forming line charging voltage. The fundamental operating impedance increment for the MITL steps is increased to 14.25 ohms providing a matched 5.25 MV, 123 kA, 70 ns output pulse. Particle-in-cell simulations (LSP) of the MITL power flow from the cell to the load predict a nominal output in agreement with the design value. The cathode (boundary) current and the vacuum flow (sheath) current from the simulations scale roughly as predicted by parapotential flow theory (M.Y. Wang et al., 1978). The increased cell voltage and core flux swing are well within the RITS-3 design levels. When the load impedance is <42.75 ohms the MITL behavior is divided into three separate phases. A vacuum precursor, a magnetic insulation phase when the operating impedance is determined by parapotential flow, and an over insulation phase where the impedance is determined by the load. The over insulation wave moves back up the MITL toward the source with a velocity of 0.3-0.6 the speed of light. The diode voltage is less than 5.25 MV and the boundary and sheath currents are observed to change significantly from those for a matched diode.
Pulsed Power Conference, 2003. Digest of Technical Papers. PPC-2003. 14th IEEE International; 07/2003
-
[show abstract]
[hide abstract]
ABSTRACT: Advanced radiography capabilities can be provided by diodes in which a <1 mm diameter cathode is immersed in a /spl sim/60 T magnetic field and pulsed to /spl sim/16 MV. An electron current of /spl sim/50 kA is constrained by the magnetic field to /spl sim/1 mm at the anode, and produces V 1 krad at 1 m. A 16 MV, 50 ns flat-top voltage adder has been designed that is optimum to develop such diodes. The adder approach is chosen to give a relatively short risetime and low prepulse. It also has the advantage of being re-configurable to provide two 8 MV pulses. The pulser uses standard Marxes, intermediate stores, and water PFLs. Novel features include an oil prepulse switch, an induction cell that is fed from one point, and a blocking network to couple two pulses to one cell. Based on detailed simulations, a design has been completed through detailed drawings and prototype hardware will be tested next year.
Pulsed Power Conference, 1999. Digest of Technical Papers. 12th IEEE International; 02/1999
-
C.L. Olson,
M.G. Mazarakis,
P.R. Menge,
J.S. Lash,
D.C. Rovang,
S.E. Rosenthal,
J.D. Boyes,
D.L. Johnson,
D.L. Smith,
J.E. Maenchen,
D.R. Welch,
B.V. Oliver, V.L. Bailey,
D. Smith
[show abstract]
[hide abstract]
ABSTRACT: Summary form only given. A needle-like, high-current, electron
beam has been produced on the Hermes III and SABRE accelerators at SNL
using inductive voltage adder (IVA) technology, and a diode consisting
of a needle cathode and a planar anode/bremsstrahlung converter which
are both fully immersed in a strong solenoidal magnetic field (12-50 T).
Desired nominal parameters are 10 MV, 40 kA, 0.5 mm radius cathode, and
5-35 cm anode-cathode gaps. High dose and small X-ray spot size are
required for radiography applications. Results are presented of initial
experiments on Hermes III and SABRE, which have produced doses up to 1
kRad@1 meter, and at lower doses, spot sizes as small as 1.7 mm diameter
Plasma Science, 1998. 25th Anniversary. IEEE Conference Record - Abstracts. 1998 IEEE International on; 07/1998
-
[show abstract]
[hide abstract]
ABSTRACT: A proof-of-concept experiment (POCE) to demonstrate the
performance of a novel recirculating induction accelerator has been
completed. The Spiral Line Induction Accelerator employs a unique
combination of features (spiral beamline, shielded off-axis gaps, and
stellarator focussing fields) which permits efficient, high-current
operation with a compact device. Initial experiments demonstrated
acceleration of 2 and 10 kA beams to 5.5 MeV and acceleration of a 12.5
kA beam to 4.5 MeV by transport around a full turn with two passes
through a single accelerating unit. Recent tests with the completed POCE
hardware achieved the program goal with acceleration of a 2.4 kA beam to
9.5 MeV
Particle Accelerator Conference, 1997. Proceedings of the 1997; 06/1997
-
[show abstract]
[hide abstract]
ABSTRACT: Methods of achieving current neutralization in fast-risetime (<3 ns) electron beams propagating in low-pressure gas are described. For this investigation, a 3-MV, 30-kA intense beam was injected into a drift cell containing gas pressures form 0.10 to 20 torr. By using a fast net current monitor (100-ps risetime), it was possible to observe beam front gas breakdown phenomena and to optimize the drift cell gas pressure to achieve maximum current neutralization. Experimental observations have shown that by increasing the drift gas pressure ( P ≈12.5 torr) to decrease the mean time between secondary electron gas collisions, the beam can propagate with 90% current neutralization for the full beam pulsewidth (16 ns)
IEEE Transactions on Plasma Science 11/1991; 19(5):855-859. · 1.17 Impact Factor
-
T.W.L. Sanford,
J.A. Halbleib,
J.W. Poukey,
T. Sheridan,
D. Muirhead,
C.E. Yagow,
K.A. Mikkelson,
R. Mock,
P.W. Spence, V.L. Bailey,
H. Kishi
Pulsed Power Conference, 1989. 7th; 02/1989
