3D-printed components for electron-ion trapping: Pre-experimental tests of functionality and ultra-high vacuum compatibility

TL;DR

This work demonstrates the viability of using Laser Powder Bed Fusion 3D-printed components to construct a microwave-driven, dual-frequency Paul trap integrated with a coaxial resonator and a calcium atomic oven for co-trapping electrons and ions. The authors show that such 3D-printed parts can reach ultra-high vacuum conditions (down to $p \approx 2.5\times10^{-10}$ mbar) using a combination of a sputter ion pump and a non-evaporable getter pump, while maintaining acceptable microwave resonance performance ($Q \gtrsim 960$ at $f \approx 2.31$ GHz). The atomic oven can produce a calcium beam with controlled heating, though it temporarily raises pressure, which can be mitigated by optimized heating schemes. Together, these results establish a foundation for future room-temperature studies of low-energy ion–electron interactions and microwave detection using 3D-printed hardware, with practical implications for compact, cost-effective quantum experiments. The paper emphasizes the balance between thermal management, vacuum integrity, and optical access in miniaturized, 3D-printed quantum devices, and provides a path toward rapid prototyping and testing of electron–ion platforms.

Abstract

We demonstrate the ultra-high vacuum compatibility of a microwave-driven electron trap and an atomic oven (for atomic beam generation) fabricated through 3D printing via Laser Powder Bed Fusion (L-PBF). The trap integrates into a coaxial microwave cavity, enabling stable, narrow-band, high-amplitude oscillations of the electric field at the electrodes. The design also supports simultaneous trapping of ions. The oven performs well in ultrahigh vacuum (UHV) environments without significant outgassing. In addition to achieving the UHV regime for 3D-printed components, pressure variations and their potential impact on electron-ion trapping experiments were investigated over a month. Our results show that experiments with electrons photodetached from trapped and laser-cooled ions are feasible with the trap and oven manufactured by the L-PBF method. These findings establish a foundation for future experiments in microwave detection and the study of low-energy ion-electron interactions at room temperature.

Figures (11)

• Figure 1: Schematic illustration of the EiTEx setup. The pumping system comprises a turbopump (TP) connected via a gate valve (GV) with an integrated sputter ion pump (SIP) and a non-evaporable getter (NEG). A cutaway view of the vacuum chamber highlights the oven assembly (OA) with electrical connections (OEC) and the coaxial trap (CT) equipped with megahertz (MI) and gigahertz (GI) signal inputs. A Pirani gauge (AG) and an ionization gauge (IG) are mounted on a side port of the vacuum chamber, while the imaging system (IS) is positioned vertically above the chamber.
• Figure 2: Photograph of the experimental setup showing the major subsystems mounted on a base plate (for public demonstration purposes). Key components are indicated: the oven assembly (OA) for atomic beam delivery, the coaxial trap (CT) for electron-ion trapping, the viewport coupler (VC) for optical access, the optical cavity (OC) for light–matter interaction, and the beam dump (BD) for blocking residual laser light
• Figure 3: 3D printed electron-ion trap designed for in-vacuum operation. (a) CAD model for printing and illustration purposes. (a1) Cross-sectional view of the outer body of cavity (A) with the resonator rod (B). Components (C1, C2) are SMA jacks for the GHz signal, used to capacitively drive the resonator, while components (D1, D2) are power push-on connectors for the MHz signal, connected to the end caps (E1, E2). (a2) Side view of the resonator, highlighting the trapping region hole (F). (b) Our 3D-printed assembly immediately after fabrication, with additive manufacturing support structures retained for mechanical stability during the printing process. (c) Trap after polishing and support removal, prepared for installation in the vacuum chamber.
• Figure 4: Baking of the EiTEx 3D-printed trap in a controlled oven. Left: Trap on a ceramic platform inside spiral heating coils for uniform heating. Right: Oven held at 165 $^\circ\text{C}$ for 5 h 16 m to ensure outgassing, structural stabilization and enhancement of electrical conductivity before vacuum integration.
• Figure 5: 3D printed atomic oven assembly designed for in-vacuum operation. (a) CAD model for printing and illustration purposes. (a1) Front view of the assembly with the oven tube (OT) installed, displayed without the heat shield. $\text{W}_1$ and $\text{W}_2$ represent the thermocouple (TC) circuit wires, which are spot-welded to the oven tube for temperature monitoring. (a2) The assembly with the heat shield slid down from the top, fully enclosing the oven tube. $\text{OE}_1$ and $\text{OE}_2$ denote the electrical connections supplying power to the oven tube. (b) Photographs of the manufactured component: (b1) inner side of the heat shield, and (b2) assembled oven with electrical connections after operation in the vacuum chamber, where the darkened region on the surface is attributed to calcium evaporation and subsequent deposition during oven use, effectively preventing atomic contamination of the trap and other components inside the chamber.