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Development of a Custom kV-amplitude, pressure-tolerant Radio-Frequency transmitter

Christian Hornhuber, Mohammad Ful Hossain Seikh, Mark Stockham, Scott Voigt, Rob Young, Alisa Nozdrina, Sanyukta Agarwal, Shoukat Ali, Kenny Couberly, Dave Besson

TL;DR

The paper documents the development and field validation of SPUNK, a pressure-tolerant, kilovolt-amplitude RF transmitter for calibrating in-ice UHEN detectors. It combines a robust, low-jitter avalanche-transistor pulser with a Marx Bank extension to achieve $V_{out}\approx$1.4 kV, rise times under $1$ ns, and operation at pressures up to $200~\text{atm}$ and temperatures down to $-50^{\circ}\mathrm{C}$. Key design elements include the Avalanche Transmission Line, Charging Circuit with equalized multi-stage voltages, Trigger Circuit with transformer isolation, a Bypass Capacitor network, and a compact physical layout suitable for borehole deployment. Field tests in the SPICE borehole demonstrated clear, high-SNR signals over 1.5–5 km to the ARA receiver array, enabling direct measurement of ice properties such as the refractive-index profile, attenuation length, and birefringence. The work provides a practical, deployable calibration tool that improves the geometric reconstruction and sensitivity of in-ice UHEN experiments.

Abstract

Current experiments seeking first-ever observation of Ultra-High Energy Neutrinos (UHEN) typically utilize radio frequency (RF) receiver antennas deployed in cold, radio-transparent polar ice, to measure the coherent RF signals resulting from neutrino interactions with ice molecules. Accurate calibration of the receiver response, sampling the full range of possible neutrino geometries, is necessary to estimate the energy and incoming direction of the incident neutrino. Herein, we detail the design and performance of a custom radio-frequency calibration transmitter, consisting of a battery-powered, kiloVolt-scale signal generator (`IDL' pulser) driving an antenna (South Pole UNiversity of Kansas antenna, or `SPUNK') capable of operating at pressures of 200 atmospheres. Performance was validated by lowering the transmitter into a borehole at the South Pole to a depth of 1740 m, yielding high Signal-to-Noise ratio signals at a distance of 5 km from the source.

Development of a Custom kV-amplitude, pressure-tolerant Radio-Frequency transmitter

TL;DR

The paper documents the development and field validation of SPUNK, a pressure-tolerant, kilovolt-amplitude RF transmitter for calibrating in-ice UHEN detectors. It combines a robust, low-jitter avalanche-transistor pulser with a Marx Bank extension to achieve 1.4 kV, rise times under ns, and operation at pressures up to and temperatures down to . Key design elements include the Avalanche Transmission Line, Charging Circuit with equalized multi-stage voltages, Trigger Circuit with transformer isolation, a Bypass Capacitor network, and a compact physical layout suitable for borehole deployment. Field tests in the SPICE borehole demonstrated clear, high-SNR signals over 1.5–5 km to the ARA receiver array, enabling direct measurement of ice properties such as the refractive-index profile, attenuation length, and birefringence. The work provides a practical, deployable calibration tool that improves the geometric reconstruction and sensitivity of in-ice UHEN experiments.

Abstract

Current experiments seeking first-ever observation of Ultra-High Energy Neutrinos (UHEN) typically utilize radio frequency (RF) receiver antennas deployed in cold, radio-transparent polar ice, to measure the coherent RF signals resulting from neutrino interactions with ice molecules. Accurate calibration of the receiver response, sampling the full range of possible neutrino geometries, is necessary to estimate the energy and incoming direction of the incident neutrino. Herein, we detail the design and performance of a custom radio-frequency calibration transmitter, consisting of a battery-powered, kiloVolt-scale signal generator (`IDL' pulser) driving an antenna (South Pole UNiversity of Kansas antenna, or `SPUNK') capable of operating at pressures of 200 atmospheres. Performance was validated by lowering the transmitter into a borehole at the South Pole to a depth of 1740 m, yielding high Signal-to-Noise ratio signals at a distance of 5 km from the source.

Paper Structure

This paper contains 19 sections, 2 equations, 13 figures, 2 tables.

Table of Contents

  1. Introduction
  2. PVA signal generation with a robust low-jitter and sub-nanosecond high voltage pulser
  3. Design
  4. Avalanche Transmission Line
  5. Charging Circuit
  6. Trigger Circuit
  7. Bypass Capacitor
  8. Marx Bank Extension Circuit MBC
  9. Physical Layout
  10. Performance Measurements
  11. Comnparison of single pulser vs Marx -- Bank double pulser with variable charging capacitors
  12. Frequency spectra for different charging capacitors
  13. Antenna Design
  14. Comparison of wall thickness and material variations
  15. Antenna Radio-Frequency characteristics
  16. ...and 4 more sections

Figures (13)

  • Figure 1: Illustration of neutrino signal generation and detection scheme used by the Askaryan Radio Array experiment at the South Pole. Neutrino ($\nu$) incident from upper left penetrates $\sim$1 km into South Polar ice, and subsequently interacts with ice molecule, resulting in 'shower' (zoomed, right); particles in shower produce both incoherent short-wave and coherent longer-wavelength (radio-frequency) radiation, then observed in 16-antenna ARA array. The goal of the calibration transmitter described here in is to simulate a neutrino interacting in-ice, producing (as in diagram) horizontally propagating RF radiation. Figure reprinted from https://pos.sissa.it/358/933/pdf.
  • Figure 2: Avalanche Pulser Circuit
  • Figure 3: Marx - Bank Extension Circuit
  • Figure 4: Avalanche Pulser Board
  • Figure 5: Marx - Bank Pulser Stack
  • ...and 8 more figures