A tandem accelerator is a type of electrostatic accelerator that utilizes the high-voltage terminal twice to achieve higher ion energy. In this accelerator, a charge exchange cell is positioned between the low-energy and high-energy sections of the accelerating tube, converting the negative ion beam into a positive one. The charge exchange cell can be categorized into two types: gaseous charge exchange cells and carbon foil-based charge exchange cells. To enhance beam transfer efficiency in a tandem accelerator, the gaseous charge exchange cell is generally preferred. This paper presents a simulation of the charge exchange process for negative carbon ions using nitrogen gas. The conversion efficiency of negative carbon ions to positive ions is calculated for various nitrogen gas throughputs.

The side-coupled standing wave accelerator tubes have a wide range of applications in linear electron accelerators due to their relatively high acceleration gradient and relatively low sensitivity to manufacturing errors. In the NSTRI-eLinac project, a dual energy electron linear accelerator is defined for cargo applications. In this accelerator, a side-coupled standing wave tube accelerates electrons to energies of 4 and 6 MeV. This tube operates at a frequency of 2998.5 MHz in the π/2 mode, fed by a magnetron with a maximum power of 2.6 MW. The most important issue in designing the accelerating tube is the interaction between the electron beam and the RF electromagnetic field to deliver the electron bunch at the desired energy with maximum efficiency and suitable output beam quality. Beam dynamics studies are essential for determining the specifications of the output beam. In this paper, the output beam characteristics for the NSTRI accelerating tube have been investigated using the STRA code. The results estimate the output beam characteristics in energies of 4 and 6 MeV at the end of the constructed tube.

The RF window has to withstand several megawatts of RF power without experiencing any physical deformity to maintain the pressure difference between vacuum and isolate gas sides. It must also have suitable and acceptable RF performance with minimum reflection and insertion loss. The design of an RF window depends on the window materials' dielectric characteristics, such as dielectric constant, permeability, and permittivity. The dielectric permittivity and permeability of window material affect the transmission of RF power. This paper presents the design and simulation of an RF window that works at a frequency of 2.998 MHz and performs thermal analyses to determine its structural stability. This RF window must withstand an average power of 3 kW. This window will used for NSTRI dual energy e-Linac Project.