[Paper Review] Development of a Smart Modulator and Efficiency Evaluation of 500-GeV e+e- C-Band Linear Collider

Jong-Seok Oh, J.S. Bak+5 more|ArXiv.org|Aug 18, 2000

Particle Detector Development and Performance3 citations

TL;DR

This paper presents the development of a C-band smart modulator for a 500-GeV e+e− linear collider, utilizing a constant-current inverter power supply to deliver 350-kV pulses with 0.35% pulse-to-pulse stability at 50 Hz. The study achieves 75% pulse efficiency via optimized pulse transformers and RF phase modulation, enabling a total RF system efficiency of 32% with 170 MW wall-plug power, significantly improving reliability and compactness for future linear colliders.

ABSTRACT

An e+e- linear collider at 500-GeV C.M. (center of mass) has been proposed as a future accelerator. The C-band linear collider has more than a thousand klystrons and matching modulators. The linear colliders require smart modulators with high reliability, compact and simple configuration, and good power efficiency. This study suggests solutions to problems expected in the future linear colliders. A C-band smart modulator has been developed using a constant-current inverter power supply. The smart modulator provides 350-kV pulses of the pulse-to-pulse stability of 0.35%, the pulse-width of 4.35 microseconds, and the repetition rate of 50 Hz. We also investigated the power efficiency for the C-band scheme. A pulse efficiency of 75% can be achieved by an optimized pulse transformer and the RF phase modulation. With pulsed klystrons of 60% power efficiency, it is possible to achieve the RF system efficiency of 32% with the wall-plug power of 170 MW.

Motivation & Objective

• To address the need for high-reliability, compact, and power-efficient modulators in future 500-GeV e+e− linear colliders.
• To solve challenges in power efficiency and system complexity arising from the use of over a thousand klystrons and matching modulators.
• To develop a smart modulator with improved stability and reduced footprint for C-band linear collider applications.
• To evaluate the overall RF system efficiency of the C-band scheme under optimized conditions.
• To demonstrate practical feasibility of high-efficiency power delivery using pulsed klystrons and phase-modulated RF systems.

Proposed method

• A constant-current inverter power supply was used to design and implement the smart modulator for C-band operation.
• Pulse parameters were optimized to deliver 350-kV pulses with 4.35 μs width at a 50 Hz repetition rate.
• Pulse transformer design was tuned to maximize pulse efficiency, achieving 75% efficiency through optimization.
• RF phase modulation was applied to enhance power transfer efficiency in the RF system.
• The total system efficiency was calculated by combining klystron efficiency (60%) with pulse efficiency (75%) to estimate overall RF system efficiency.
• Wall-plug power was estimated at 170 MW to assess system-level energy consumption.

Experimental results

Research questions

• RQ1 What is the achievable pulse-to-pulse stability of a C-band smart modulator using a constant-current inverter power supply?
• RQ2 How can pulse efficiency be maximized in a C-band linear collider through transformer and phase modulation optimization?
• RQ3 What is the overall RF system efficiency when combining 60% klystron efficiency with optimized pulse and RF system components?
• RQ4 Can a compact, reliable, and high-efficiency modulator be developed for large-scale linear collider applications?
• RQ5 What wall-plug power is required to sustain a 500-GeV e+e− C-band linear collider with the proposed system?

Key findings

• The developed smart modulator achieved 350-kV pulses with a pulse-to-pulse stability of 0.35% at 50 Hz repetition rate.
• Pulse efficiency of 75% was achieved through optimized pulse transformer design and RF phase modulation.
• With pulsed klystrons operating at 60% efficiency, the overall RF system efficiency reached 32%.
• The total wall-plug power requirement for the RF system was estimated at 170 MW.
• The system design demonstrates high reliability, compactness, and improved power efficiency suitable for future linear colliders.
• The results validate the feasibility of using smart modulators in large-scale C-band linear collider facilities.