[Paper Review] PIC simulation of particle behavior in an Inertial Electrostatic Confinement Fusion device using XOOPIC code

D. Bhattacharjee, S. Adhikari+2 more|arXiv (Cornell University)|Feb 14, 2020

Fusion and Plasma Physics Studies4 citations

TL;DR

This study uses the open-source XOOPIC code to perform kinetic Particle-in-Cell (PIC) simulations of ion dynamics in a cylindrical Inertial Electrostatic Confinement Fusion (IECF) device, revealing the formation of multiple potential wells and ion densities up to 10¹⁶ m⁻³ at the core. Simulated ion energy distribution functions and plasma potential profiles match experimental data, validating the model and guiding optimization of IECF discharge parameters.

ABSTRACT

The kinetic analyses are quite important when it comes to understand the particle behavior in any device as they start to deviate from continuum nature. In the present study, kinetic simulations are performed using Particle-in-Cell (PIC) method to analyze the behavior of ions inside a cylindrical Inertial Electrostatic Confinement Fusion (IECF) device which is being developed as a tabletop neutron source. Here, the lighter ions, like deuterium are accelerated by applying an electrostatic field between the chamber wall (anode) and the cathode (cylindrical gridded wire), placed at the center of the device. These ions recirculate across the cathode grid, which in turn capable of producing fusion reaction at the central region of the device. An open source PIC code (XOOPIC) is used in our study to simulate the ion dynamics at different experimental conditions. The plasma potential profiles obtained from the simulated results indicate the formation of multiple potential well structures inside the cathode grid depending upon the applied cathode potential (from $-1$ to $-5~kV$). The ion density at the core region of the device is found to be of the order of $10^{16}~m^{-3}$, which closely resembles the experimental observations. Spatial variation of Ion Energy Distribution Function (IEDF) has been measured in order to observe the characteristics of ions at different cathode voltages. Finally, the simulated results are compared and found to be in good agreement with the experimental profiles. The present analysis can serve as a reference guide to optimize the technological parameters of the discharge process in IECF devices.

Motivation & Objective

• To understand the kinetic behavior of ions in an Inertial Electrostatic Confinement Fusion (IECF) device under varying electrostatic fields.
• To model ion recirculation and confinement dynamics in a cylindrical IECF setup using a particle-in-cell approach.
• To validate simulated plasma potential and ion density profiles against experimental observations for device optimization.
• To analyze the spatial variation of the Ion Energy Distribution Function (IEDF) at different cathode voltages.
• To provide a reference framework for tuning technological parameters in IECF devices using kinetic simulation.

Proposed method

• Employing the open-source XOOPIC code to simulate ion dynamics in a cylindrical IECF device with a central cathode grid and chamber wall as anode.
• Applying electrostatic fields between -1 kV and -5 kV to the cathode to accelerate deuterium ions and induce recirculation.
• Tracking ion trajectories and charge accumulation to compute plasma potential profiles and ion density distributions.
• Calculating the Ion Energy Distribution Function (IEDF) at various radial positions to assess ion energy characteristics.
• Using the PIC method to solve self-consistent Poisson and Maxwell equations for kinetic plasma behavior.
• Comparing simulated results with experimental data to validate the model across different cathode voltages.

Experimental results

Research questions

• RQ1 How do multiple potential well structures form within the cathode grid at different cathode potentials in an IECF device?
• RQ2 What is the spatial distribution of ion density in the core region under varying applied voltages?
• RQ3 How does the Ion Energy Distribution Function (IEDF) vary radially at cathode potentials from -1 kV to -5 kV?
• RQ4 To what extent do simulated plasma potential and ion density profiles match experimental measurements?
• RQ5 Can kinetic simulations with XOOPIC accurately predict key performance indicators for IECF neutron source optimization?

Key findings

• Multiple potential well structures form inside the cathode grid due to the applied cathode potential, with well depth increasing from -1 kV to -5 kV.
• The ion density at the core region reaches approximately 10¹⁶ m⁻³, closely matching experimental observations.
• The Ion Energy Distribution Function (IEDF) shows distinct spatial variations, indicating energy-dependent ion behavior across the device radius.
• Simulated plasma potential profiles exhibit good agreement with experimental data across the tested voltage range.
• The simulated ion dynamics and energy distributions align well with experimental profiles, validating the XOOPIC-based model.
• The study provides a validated simulation framework for optimizing discharge parameters in IECF devices for enhanced neutron yield.