VORPAL Success Story: Brookhaven

DOE/NP Computations Lead to Cost Savings in Scientific Instruments

Figure 1. The simulated dynamical friction force along the z-axis is shown (symbols) as a function of the angle between the ion velocity vector v_ion and the z-axis. For B=0 (no undulator), simulations agree with theory (red line). As B is increased, the smaller simulated forces can be explained by replacing the minimum impact parameter with the electron wiggle amplitude in the Coulomb logarithm. Click for the full-sized graph.

Computations supported by the DOE/NP SBIR program and now also by SciDAC were instrumental in design modifications of the proposed electron cooling system for RHIC that led to cost reductions estimated in the tens of millions of dollars. Rather than using a technically challenging high-field solenoid magnet and 20 nC magnetized electron bunches [1], the new design specified conventional undulator magnet technology with 5 nC electron bunches [2]. Tech-X Corp. worked collaboratively with BNL scientists to simulate dynamical friction forces from first principles. The initial effort [3] established confidence in the new algorithms implemented within the parallel VORPAL framework, and contributed directly to the solenoid- based design. Subsequent algorithmic improvements and additional VORPAL simulations [4,5] confirmed the conjecture that the magnetic fields of the undulator would only reduce the friction force logarithmically (Fig. 1) and, thus, be a much cheaper yet viable alternative. Although detailed cost estimates are not available, it is agreed that the modified design for the RHIC electron cooler would be tens of millions of dollars less expensive than the previous design, with much lower technical risk. The computational effort at Tech-X Corp. played a key role in the development of this improved design and the expected cost savings.

1. I. Ben-Zvi et al., PAC Proc., p. 2741 (2005).

2. I. Ben-Zvi et al., PAC Proc., p. 1938 (2007).

3. DOE/NP SBIR, "Parallel Simulation of Electron Cooling," Aug. 2001 - May 2005, DE-FG03-01ER83313.

4. DOE/NP SBIR, "Smart Particle Electron Cooling Simulations," July 2004 - July 2008, DE-FG02-04ER84094.

5. G.I. Bell et al., J. Comput. Phys. (2008), doi:10.1016/j.jcp.2008.06.019.

A visualization of VORPAL simulating a laser pulse (green) striking an aluminum sphere (blue) with a helium coating and ejecting electrons (white).

VORPAL simulation of an electron beam propagating in the superconducting Tesla cavity. Particle color (and diameter) represents the transverse energy. The isosurfaces represent the longitudinal electric field.

VORPAL Frequently Asked Questions

• What is current version of VORPAL?

• What is VORPAL?

• When will VORPAL be supported on my favorite platform?

• Where should I send my questions related to VORPAL?

What is current version of VORPAL?

What is VORPAL?

When will VORPAL be supported on my favorite platform?

The majority of the VORPAL users are using the Linux workstations. It is costly to maintain wide ranging cross-platform compatibility. If you discover problems with your favorite OS or compiler, please send a message to the VORPAL users list.

Where should I send my questions related to VORPAL?

Address technical questions via email to the VORPAL discussion list.

Please contact Tech-X directly for sales, collaboration, and other questions.

VORPAL Animations

Tech-X has turned a variety of simulation data into visualizations that are both interesting and informative. Creating 3D animations from simulations such as VORPAL allows researchers to have a better overall picture of the physics involved, as well as highlighting effects that may not otherwise be obvious.

Crab Cavity Visualization: The award-winning crab cavity visualization presented at SciDAC08.	Fields on a Coaxial Cavity: VORPAL data created with input file coax_test.pre. This movie shows 4 different views of the fields on a coaxial cavity after a sinusoidal current ring is applied to a small width between the inner and outer walls.
2D Simulation of Electron Density: The electron density in a 2D VORPAL simulation of the expansion of a two-component plasma in an ambient magnetic field.	Radio Frequency Electron Gun: VORPAL simulations of a radio frequency electron gun design considered for RHIC electron cooling injector at the Brookhaven national lab.
Laser-wakefield Experiment.Simulation: VORPAL simulating a laser-wakefield experiment.	Wakefields: Wakefields generated by the propagation of an electron beam in a TESLA cavity.
Cut-away View: Cut-away view through the International Linear Collider (ILC) cavities.	3D Simulations of Lightning: 3D electromagnetic simulations of lightning striking an above-ground oil storage tank.
Compact Pulsed Neutron Source: VORPAL simulation of a compact pulsed neutron source.	Thermal Plasma: A thermal plasma consisting of electrons (small spheres) and ions (large spheres), colored by computational domain they sit on.
Laser Pulse: A laser pulse hitting an overdense spherical mirror coated with an underdense material.	TESLA Cavity: The geometry of a TESLA cavity in VORPAL.

Computational assessment of mitigation of lightning-induced oil tank fires

Lightning strikes on oil tanks at oil storage facilities can result oil tank fires that lead to major financial losses. These oil tank fires appear to be caused by the large inductively generated electric fields in the gap between the floating roof and the sides of the oil tank. It has been proposed to eliminate these large electric fields through adding electrical shorts across the gap between the walls of the tank and the roof. However, some assessment of efficacy of these shorts is needed to have confidence in this methodology.

Download the full presentation (PowerPoint)

Preliminary Results

VORPAL was used to do some preliminary calculations, computing the induced electric fields for a 30 cm computational resolution (understandably inadequate). These computations show qualitatively that adding shorts can result in a favorable reduction of the electric field in the gap. Animations produced from VORPAL data with and without the short appear below.

These are results from two different simulations, both with a lightning strike of the same form. The lightning current profile is shown in the upper left corner. On the left is a non-shorted oil tank, while on the right is the shorted tank. As the lightning strike progresses, surfaces of constant electric field are shown. The magnitude of the electric field is shown in the upper right, with the end of the scale being 1 MV/m. The simulations show that the peak electric field in the gap approaches 1 MV/m with no mitigation, but remains below 0.2 MV/m with when a short circuit is added.