Compact ion accelerators for nuclear materials and ...

Compact ion accelerators for nuclear materials and manufacturing

Thomas SchenkelLawrence Berkeley National Laboratory, Berkeley, CA

February 25, 2021

This work is supported by ARPA-E. Work at LBNL was conducted under the auspices of DOE under contract DE-AC0205CH11231.

Rad hard materials are important for the success of future fission and fusion reactors

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• Neutron irradiation leads to structural damage and materials modifications

• Irradiation with energetic ions can mimic neutron damage

• Development of nuclear materials can be accelerated with better irradiation capabilities

• In this project we are developing a new class of ion accelerators that can deliver more ions on target faster and at lower cost

• Our new class of particle accelerators can be applied for nuclear materials development, surface modification of materials, ion implantation, ion beam analysis, ... Gary Was et al., High Fidelity Ion Beam Simulation of High Dose

Neutron Irradiation, https://www.osti.gov/servlets/purl/1437129

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This is a collaboration between Berkeley Lab and Cornell University

A. Lal (co-PI) K. K. Afridi D. Ni S. Sinha Y. Hou V. Gund

• Accelerators, beam physics, ion sources and beam transport, RF, … http://atap.lbl.gov/

T. Schenkel (PI), Q. Ji, A. Persaud, P. Seidl, W. Waldron, G. Giesbrecht, T. Bauer, Z. Qin

• MEMS fabrication, Chip-scale particle accelerators, RF power amplifier … http://www.sonicmems.ece.cornell.edu/

We have achieved ion acceleration to 59 keV in a MEMS-based multi-beamlet RF LINAC

‣ 16 wafers (4”), 8 acceleration gaps, column length: 12 cm• RF frequency: 12 MHz, RF amps by Airity (near board)• Injection energy 7 keV, 120 beamlets, argon ion current of up to 0.5

mA (injected, transmission efficiency measurements in progress• Acceleration by 6.5 kV/gap, total ion energy added: +52 keV• Acceleration gradient is ~ 1 MV/m • No x-ray hazard from back-streaming electrons• No large insulator to stand off 50 kV• Next steps: >100 keV, ion current >1 mA and increase duty cycle

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RF stack SlitFaraday cup

Deflector electrodes

Technology to market

• Y. Hou, S. Sinha, D. Ni, Q. Ji, A. Persaud, P. Seidl, T. Schenkel, A. Lal and K.K. Afridi, "A 50-MHz Kilovolt-Scale Power Amplifier for Ion-Beam Accelerator Utilizing an Optimized Toroidal Inductor," Proceedings of the IEEE Energy Conversion Congress and Exposition (ECCE), Detroit, MI, October 2020

• S. Sinha, Y. Hou, D. Ni, Q. Ji, A. Persaud, P. Seidl, T. Schenkel, A. Lal and K.K. Afridi, "A 27.12-MHz 10-kV Power Amplifier for Compact Particle Accelerators Utilizing an Optimized," 2020 IEEE Energy Conversion Congress and Exposition (ECCE), Detroit, MI, USA, 2020, pp. 5452-5457, doi: 10.1109/ECCE44975.2020.9236008.

• ”Scaling of a compact multi-beam ion accelerator to higher beam power for plasma heating”, APS DPP meeting, Nov. 2020

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• Potential first viable products includeo Ion implanters (e. g. nitrogen into metals)o Neutron generators (e. g. to replace radiological sources)

• Conversations with potential partners ongoing

• Development steps to further increase beam power

Compact ion accelerators for nuclear materials and manufacturing

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‣ For new teams– Foster good communication with the ArpaE team

‣ For ArpaE– Help with T2M and potential applications outside of our core area(s)

Feedback

‣ Extra slides

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• Pulsed induction linac (12 m)• 1 MeV, 2 ns, mm, ≥2 A peak• 200x drift compression• P. A. Seidl et al. NIM A (2015)

• Radio frequency quadrupole (RFQ)

• 2 MeV, 0.01 A, cw• 4 m long, 0.4 m cross section• Z. Zouhli, D. Li et al. IPAC2014

How can we scale ion beams to high beam power at lower cost?

à MEMS based multi-beam linacs

• High Current Experiment• injection, matching and transport at

heavy ion fusion driver scale• 1 MeV, 0.2 A, 5 µs, ~12 m• 0.4 m cross section• M. Kireeff-Covo, et al., PRL (2006)

Examples of high power ion accelerators at Berkeley Lab

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Multiple-Electrostatic-Quadrupole-Array Linear Accelerator (MEQALAC)

• A high current beam from many small beamlets for higher beam power and current densities

• 1980s: ~ 1 cm beam apertures, lattice period a few cm, based on copper and steel• Al Maschke et al., early 1980s; Thomae et al., Mat. Science & Eng., B2, 231 (1989)

• Can we develop multi-beam ion accelerators that can be scaled to high beam power at low cost ? à Yes, MEMS based RF-linacs !

MEMS based multi-beam linear RF accelerators

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• up to 0.5 mA of Ar+ extracted to date

10 cm

120 beamlets with 3 mm spacing120-beamlet ESQ

4cm

8cm15.5cm

13.5 and 27 MHz RF amplifiers, achieved 6.5 kV/gap

27MHz RF amplifier is ready for beam tests

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• 100 V input, 6.9 kV amplifier output

• The ability to increase the RF acceleration frequency is important to keep the gradient at ~1 MV/m

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More detailed summary and outlook

• We have demonstrated ion acceleration to 59 keV in a stack of 16 RF wafers with 120 beamlets

• We are developing RF power amplifiers at 13.5 MHz and 27.1 MHz

• We have achieved ion acceleration with 6.5 kV/gap

• The effective gradient is ~1 MV/m

• Next steps - scale beam energy to >100 KeV - scale beam current to >1mA- ion implant and surface modification demonstrations-scaling to higher beam power for plasma heating

• Q. Ji et al, in preparation• Earlier publications on the concept: • A. Persaud, et al., RSI 88, 063304 (2017)• P. A. Seidl et al., RSI (2018) • K. Vinayakumar, et al, J. Appl. Phys. 125,

194901 (2019)