Measurements of multipactor thresholds under several propagation modes
Abstract
The multipactor effect, a detrimental electron avalanche in vacuum RF systems, can degrade their performances by causing impedance mismatches, thermal loads, and even destructive breakdowns. While theoretical and numerical studies have explored its dependence on RF propagation modes, experimental validation remains limited. This paper presents an experimental investigation of multipactor thresholds in a coaxial geometry under varying propagation modes (from pure travelling wave to standing wave) using the MULTIPAC test bench at LPSC Grenoble, France. Measurements at 140 MHz (where f • d ≈ 1.5 GHz mm) confirm that the lower power threshold decreases with increasing reflection coefficient, in agreement with Somersalo's scaling law. Meanwhile, the voltage thresholds show no significant dependence on the propagation mode, supporting predictions from Pérez, Romanov, and Sleiman. Experimental challenges such as surface conditioning and pickup probe polarization effects are discussed, along with proposed improvements on the test bench. These results provide critical insights for the design of robust RF systems in particle accelerators, fusion devices, and satellite payloads.
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BibTeX
@misc{placais2026measurements,
title = {{Measurements of multipactor thresholds under several propagation modes}},
author = {Adrien Plaçais and Eva Al Hajj Sleiman and Julien Angot and Yolanda Gómez-Martínez and Thibault Hamelin and Julien Hillairet and Julien Marpaud and Samuel Roni and Martin Vénière},
howpublished = {HAL},
year = {2026},
month = aug,
url = {https://hal.science/hal-05796617v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Measurements of multipactor thresholds under several propagation modes
AU - Adrien Plaçais
AU - Eva Al Hajj Sleiman
AU - Julien Angot
AU - Yolanda Gómez-Martínez
AU - Thibault Hamelin
AU - Julien Hillairet
AU - Julien Marpaud
AU - Samuel Roni
AU - Martin Vénière
PY - 2026
DA - 2026/08/31
PB - HAL
UR - https://hal.science/hal-05796617v1
AB - The multipactor effect, a detrimental electron avalanche in vacuum RF systems, can degrade their performances by causing impedance mismatches, thermal loads, and even destructive breakdowns. While theoretical and numerical studies have explored its dependence on RF propagation modes, experimental validation remains limited. This paper presents an experimental investigation of multipactor thresholds in a coaxial geometry under varying propagation modes (from pure travelling wave to standing wave) using the MULTIPAC test bench at LPSC Grenoble, France. Measurements at 140 MHz (where f • d ≈ 1.5 GHz mm) confirm that the lower power threshold decreases with increasing reflection coefficient, in agreement with Somersalo's scaling law. Meanwhile, the voltage thresholds show no significant dependence on the propagation mode, supporting predictions from Pérez, Romanov, and Sleiman. Experimental challenges such as surface conditioning and pickup probe polarization effects are discussed, along with proposed improvements on the test bench. These results provide critical insights for the design of robust RF systems in particle accelerators, fusion devices, and satellite payloads.
ER -