Induction voltage adder architectures and electrical characteristics

Abstract

In this paper we use three different designs for induction voltage adders to be used in radiographic x-ray sources to illustrate the differences between possible IVA architechlres, and between their electrical characteristics as these affect the radiographic diodes that the IVAs drive. The architectures are chosen considering the spaces in which the IVAs must fit, and the electrical characteristics are determined by the approaches chosen for the IVA electrical subsystems. We describe the status of the various IVA technologies. The IVAs, (RITS, the AWE HRF and URSA) are large systems with similar output parameters in the 12-16 MV range.L OVER-ALL IVA DESCRIPTIONS The radiographic integrated test stand (RITS) [I] was designed to explore advanced IVA designs and their characteristics and limitations, and to drive diodes that attempt to provide the small x-ray source size (in the one to a few mm diameter range) that radiographers need. The output parameters of the twelve-cell RITS (Fig. 1) are 16 MV, 150 kA, 70 ns. A three-cell version (RITS-3) is in operation at Sandia; it has functioned in accordance with design, and many publications have described its operation and its use to study vacuum power flow [2,3]. Figure 2 shows the ten-cell IVA design formulated by PSD and AWE for AWE'S Hydrodynamic Radiographic Facility (HRF). Its output is 14 MV, 100 or 140 kA (two versions), 60 ns. The HRF IVA is still in the design phase, hut a detailed electrical model and well-defmed mechanical design allows its electrical characteristics to be understood very well. The Blumlein pfl is being prototqped. Figure 3 shows the design known as URSA, recently developed by PSD for LANL. Its parameters are 12 MV, 125 kA, 60 ns. It is an eight-cell IVA designed to fit tight space constraints in a building at a LANL explosive test site. No URSA hardware has yet been built.The electrical output requirements are very similar for these three WAS. All have negative output; impedances and pulse durations are very similar. RITS, HRF, and URSA are in a sequence that has slightly decreasing voltage and power. A negative output polarity makes electrons at the diode travel towards the object to be radiographed emitting more electrons towards the object.

Effects of current asymmetry on the electron sheath of magnetically-insulated induction voltage adders

“…输出电压和功率密度 [20][21][22] . 当MIVA作为X射线闪光照 相驱动源时, 每级感应腔一般仅馈入单路脉冲, 这种馈 入方式导致注入电流空间非均匀分布 [29][30][31] , 从而对感 应腔电气参数、功率传输和MIVA性能产生影响 [32][33][34][35] .…”

Azimuthal Transmission Lines for Inductive Voltage Adders With Four PFLs Driving Simultaneously or Separately

“…To obtain better uniformity of feed currents, it is usually necessary to optimize the profiles of azimuthal lines, and to choose some appropriate connection configurations between the azimuthal lines and the cathode plates [3], [5], [7], [12], [13]. However, this will increase the azimuthal impedance and azimuthal transit time, conflicting with reducing azimuthal line inductance mentioned previously.…”

“…M AGNETICALLY insulated inductive voltage adders (MIVAs) are widely used in radiography and effect simulations [1]- [3]. One significant advantage of MIVA is the modular and flexible architecture, which allows MIVA systems easily extend to operate at various modes or configurations.…”

Evaluation of Self-Magnetically Pinched Diodes up to 10 MV as High-Resolution Flash X-Ray Sources

“…Because LIAs are many times more expensive than an equivalent pulsed-power machine, the Atomic Weapons Establishment (AWE), Aldermaston, U.K., has chosen a magnetically insulated, inductive-voltage adder (IVA) technology for their Hydrodynamic Research Facility (HRF). The design parameters for the IVA currently envisioned for the HRF are 14 MV and 140 kA [3]. One of the biggest challenges with pulsed-power-driven radiography is to demonstrate that both the dose and spot-size goals can be achieved at these voltage and current levels.…”

“…Since self-pinched diodes rely on a strong self-magnetic field, they typically operate with two-to-three times lower impedance ( ) than the immersed-B or paraxial diodes. The present IVA design for the HRF has the flexibility to be converted to lower impedance to drive either a RPD or a SMPD [3]. In this mode, the IVA will operate at about 10 MV and 200 kA.…”