One of APELC’s greatest strengths is our dedication to customer service, beginning at the quoting process and continuing through the full lifecycle of our products. This approach allows us to truly listen to and meet our clients’ specific requirements—no matter how complex or technical. We’d like to share a recent case study that showcases this commitment through a unique RS105 system upgrade designed for combined-environment High-Altitude Electromagnetic Pulse (HEMP) testing.
CASE STUDY: RS105 System for Combined-Environment HEMP Testing
Background:
The customer who initially inquired about this system was a prior APELC client who had purchased a similar system in 2016. The original purchase was a 2m EUT RS105 system for testing assets against a high-altitude nuclear EMP short/E1 pulse (see our previous blog on this topic here). Several new requirements arose since the original purchase and the customer desired a new RS105 system with additional capabilities, including:
- Low-jitter (<10ns) timing for combined environment testing
- Reduction of guy-wire footprint for installation in a limited volume
Many of the initial customer interactions leading to this new simulator purchase took place on-site at the customer’s facility. While there for training and maintenance of the 2016 system, our sales engineer had multiple discussions with the customer about what could be improved on the existing system. During these conversations, APELC learned that the customer was attempting to use the original system for combined-environment testing. This is a type of nuclear survivability testing in which multiple radiation environments are generated simultaneously to more accurately represent the threat. In this instance, the customer wanted to time the firing of the RS105 simulator with their prompt-gamma radiation simulator. We advised that the current RS105 system would require modification to its trigger circuit to achieve this. Several modifications were made to the trigger circuit by the customer, and in the end only a slight improvement in timing/jitter was realized.
Because the customer had multiple departments that required HEMP short-pulse testing, the decision was made to purchase a new system that could be transported and set up at multiple sites, with the old system as an additional resource to avoid downtime waiting for use of the simulator. The new simulator would address the two requirements mentioned above, while providing our updated design for both the pulse generator and the control interface. A more detailed description of the requirements is presented below.
Customer requirements:
1) Low-jitter (<10ns) timing for combined environment testing
As mentioned above, the customer wanted a MIL-STD-461G/RS105 compliant simulator for up to 2m high EUTs that could be used in combined environment testing. Because a high-altitude nuclear burst generates multiple radiation environments within nanoseconds of each other, the simulator for the initial E1 short-pulse (~2ns risetime and ~25ns FWHM double-exponential waveform) would need to have low timing jitter (<10ns) and an external means of triggering to time the E1 pulse with the prompt gamma pulse generated by their equipment.
2) Reduction of guy-wire footprint for installation in a limited volume
The location for the APELC RS105 system when installed for combined-environment testing was surrounded by large concrete walls on both sides. This limited the overall footprint such that the anchor points of the 45-degree guy-wires would not fit. Multiple discussions occurred by phone, email and at the customer site to come up with a solution.
APELC Solutions
Upgraded Trigger Circuit for Precision Timing
To address the timing requirement, APELC employed a thyratron-based trigger circuit—known for its <20ns rise-time and low-jitter capabilities—replacing the high-voltage relay trigger used in the original setup (which the customer chose to lower cost and greater availability of a high-voltage relay for triggering the Marx instead of a thyratron-based circuit). This ensured precise, reliable timing suitable for the customer’s combined-environment tests (the timing of the system is highly dependent on the type of switch used in the trigger circuit, the relay limited the system jitter to milliseconds as opposed to nanoseconds). The system’s control interface was also upgraded to include a PLC-based touchscreen with options for internal or external triggering and an SMA port for receiving TTL pulses from the customer’s delay generator (both shown in the figures below).
Why This Matters: By enhancing timing accuracy, we enabled the customer to synchronize the RS105 simulator with their gamma radiation equipment, ensuring realistic testing conditions in critical environments.
Figure 1 PLC-based touchscreen/remote control platform showing External Trigger/Onboard Trigger selection
Figure 2 Rear panel of the 2m RS105 PLC control unit showing external trigger input (Item 6)
Custom Guy-Wire Solution for Tight Spaces
Collaborating with the customer’s engineering team, we developed a solution using high-strength fiberglass poles and concrete ballast footings. This design offered stability without the need for traditional guy-wires, enabling safe, effective operation within the limited footprint.
Why This Matters: This adjustment-maintained system integrity and safety while adapting to a restrictive space, ensuring the system could operate where conventional installations wouldn’t be feasible.
Post-Delivery Support
Following delivery, our sales engineer visited the customer site to assist with installation, training, and system verification. At APELC, we understand that reliable performance starts with thorough training. By ensuring the customer’s team was well-prepared, we facilitated their success in using the system independently and with confidence. We take pride in the ease of use our systems provide, but also know that any pulsed power system has unique quirks and intricacies that can halt a customer’s test if they are not properly trained before using the system without an APELC representative present.
Even after installation, APELC’s support continued through ongoing phone and email assistance, addressing questions on maintenance and operational intricacies. As engineers, we thoroughly enjoy working with our customers to solve a problem. Whether that problem-solving occurs in the scoping of the system requirements or after delivery, APELC works hard to ensure our systems are reliable and that we are always a phone call away if there is a question or concern.
