Author: Johnson, R.P.
Paper Title Page
MOPPC036 Influence of Intense Beam in High Pressure Hydrogen Gas Filled RF Cavities 208
 
  • K. Yonehara, M.R. Jana, M.A. Leonova, A. Moretti, M. Popovic, T.A. Schwarz, A.V. Tollestrup
    Fermilab, Batavia, USA
  • M. Chung
    Handong Global University, Pohang, Republic of Korea
  • M.G. Collura
    Politecnico di Torino, Torino, Italy
  • G. Flanagan, R.P. Johnson, M. Notani
    Muons, Inc, Batavia, USA
  • B.T. Freemire, Y. Torun
    IIT, Chicago, Illinois, USA
 
  Funding: This work is supported by US DOE under contract DE-AC02-07CH11359.
Breakdown plasma in a high-pressure hydrogen gas filled RF cavity has been studied from a time domain spectroscopic light analysis. The observed breakdown plasma temperature and density reached 21,000 K and 1020 cm-3, respectively. The electron recombination rate has been evaluated from the decay of plasma density in various gas pressures. The recombination mechanism in dense plasma will be discussed. Finally, the similarity and difference of the breakdown processes between the high-pressure hydrogen gas filled RF cavity and a vacuum RF one will be discussed.
 
 
MOPPC039 Electron Recombination in a Dense Hydrogen Plasma 217
 
  • B.T. Freemire, P.M. Hanlet
    IIT, Chicago, Illinois, USA
  • M. Chung
    Handong Global University, Pohang, Republic of Korea
  • M.G. Collura
    Politecnico di Torino, Torino, Italy
  • M.R. Jana, C. Johnstone, T. Kobilarcik, G.M. Koizumi, M.A. Leonova, A. Moretti, M. Popovic, T.A. Schwarz, A.V. Tollestrup, Y. Torun, K. Yonehara
    Fermilab, Batavia, USA
  • R.P. Johnson
    Muons, Inc, Batavia, USA
 
  Funding: US DOE under contract DE-AC02-07CH11359.
A high pressure hydrogen gas filled RF cavity was subjected to an intense proton beam to study the evolution of the beam induced plasma inside the cavity. The electron recombination rate with the dense ionized hydrogen plasma has been measured under varying conditions. Recombination rates as high as 10-7 cm3/s have been recorded. This technique shows promise in the R&D program for a muon accelerator. The use of hydrogen, both as a way to prevent breakdown in an RF cavity and as a mechanism for cooling a beam of muons, will be discussed.
 
 
MOPPC040 Study of Electronegative Gas Effect in Beam-Induced Plasma 220
 
  • M.A. Leonova, M.R. Jana, A. Moretti, M. Popovic, T.A. Schwarz, A.V. Tollestrup, K. Yonehara
    Fermilab, Batavia, USA
  • M. Chung
    Handong Global University, Pohang, Republic of Korea
  • M.G. Collura
    Politecnico di Torino, Torino, Italy
  • B.T. Freemire, P.M. Hanlet, Y. Torun
    IIT, Chicago, Illinois, USA
  • R.P. Johnson
    Muons, Inc, Batavia, USA
 
  Funding: This research was supported by US DOE under contract DE-AC02-07CH11359.
Muon Colliders and Neutrino Factories call for R&D for a high-gradient RF system capable of operating in a high magnetic field. Adding a high pressure gas inside an RF cavity (HPRF) prevents cavity breakdown, allowing higher gradients in a magnetic field. A high-energy beam passing through an HPRF cavity ionizes the gas, producing plasma. Plasma electrons absorb cavity’s energy, reducing the energy available for beam acceleration. Doping cavity gas with electronegative gas (gas that tends to attract and bond electrons) reduces the number of plasma electrons. The experiments were carried out at the MuCool Test Area (MTA) facility at Fermilab. Different concentrations of an electronegative gas SF6 were added to hydrogen gas. The results of room-temperature tests showing a great reduction in power drop in the cavity will be presented. However, a realistic cavity would operate at liquid nitrogen temperature, where SF6 freezes. Thus, a search for a better electronegative gas candidate is underway; we plan to test oxygen-doping next.
 
 
MOPPC045 Scaled Electron Model of a Dogbone Muon RLA with Multi-pass Arcs 235
 
  • S.A. Bogacz, A. Hutton, G.A. Krafft, V.S. Morozov, Y. Roblin
    JLAB, Newport News, Virginia, USA
  • K.B. Beard, R.P. Johnson
    Muons, Inc, Batavia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Supported in part by USDOE STTR Grant DE-FG02-08ER86351.
The design of a dogbone RLA with linear-field multi-pass arcs was earlier developed for accelerating muons for a future Neutrino Factory and Muon Collider. It allows for efficient use of expensive RF while the multi-pass arc design based on linear combined-function magnets exhibits a number of advantages over single pass or pulsed arc designs. Such an RLA may have applications going beyond muon acceleration. This paper describes a possible straightforward test of this concept by scaling a GeV scale muon design for electrons. Scaling muon momenta by the muon-to-electron mass ratio leads to a scheme in which a 4.35 MeV/c electron beam is injected in the middle of a 2.9 MeV/pass linac with two double-pass return arcs, and is accelerated to 17.4 MeV/c in 4.5 passes. All spatial dimensions including the orbit distortion are scaled by a factor of 7.5, which arises from scaling the 200 MHz muon RF to a readily available 1.5 GHz. The footprint of a complete RLA fits in an area of 25 by 7 m. The scheme utilizes only fixed magnetic fields including injection and extraction. The hardware requirements are not very demanding, making it feasible to utilize the existing technologies.
The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.
 
 
MOPPD047 Progress of Surface Plasma H Ion Source with Saddle RF Antenna Plasma Generator 469
 
  • V.G. Dudnikov, R.P. Johnson
    Muons, Inc, Batavia, USA
  • S.N. Murray, T.R. Pennisi, C. Piller, M. Santana, M.P. Stockli, R.F. Welton
    ORNL, Oak Ridge, Tennessee, USA
 
  Funding: Supported in part by SBIR Grant 4729 · 09SC02690.
Progress in development of RF H surface plasma source (SPS) with saddle (SA) RF antenna which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability will be considered. Several versions of new plasma generators with a small Al2O3chamber and different antennas and magnetic field configurations were tested in the SNS small Test Stand. A prototype SA SPS was installed in the Test Stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency of 1.6 mA/kW. Control experiments with H beam produced by SNS SPS with internal and external antennas in the similar conditions were conducted. A new version of the RF triggering plasma source (TPS) has been designed and fabricated. A Saddle antenna SPS with water cooling is being fabricated for high duty factor testing
 
 
TUPPD010 Helical Muon Beam Cooling Channel Engineering Design 1425
 
  • G. Flanagan, R.P. Johnson, G.M. Kazakevich, F. Marhauser, M.L. Neubauer
    Muons, Inc, Batavia, USA
  • V.S. Kashikhin, M.L. Lopes, G.V. Romanov, M.A. Tartaglia, K. Yonehara, M. Yu, A.V. Zlobin
    Fermilab, Batavia, USA
 
  Funding: Supported in part by DOE STTR Grant DE-SC0006266
The Helical Cooling Channel (HCC), a novel technique for six-dimensional (6D) ionization cooling of muon beams, has shown considerable promise based on analytic and simulation studies. However, the implementation of this revolutionary method of muon cooling requires new techniques for the integration of hydrogen-pressurized, high-power RF cavities into the low-temperature superconducting magnets of the HCC. We present the progress toward a conceptual design for the integration of 805 MHz RF cavities into a 10 T Nb3Sn based HCC test section. We include discussions on the pressure and thermal barriers needed within the cryostat to maintain operation of the magnet at 4.2 K while operating the RF and energy absorber at a higher temperature. Additionally, we include progress on the Nb3Sn helical solenoid design
 
 
TUPPD011 Studies of the Twin Helix Parametric-resonance Ionization Cooling Channel with COSY INFINITY 1428
 
  • J.A. Maloney, K.B. Beard, R.P. Johnson
    Muons, Inc, Batavia, USA
  • A. Afanasev
    GWU, Washington, USA
  • S.A. Bogacz, Y.S. Derbenev, V.S. Morozov
    JLAB, Newport News, Virginia, USA
  • B. Erdelyi
    Northern Illinois University, DeKalb, Illinois, USA
 
  Funding: Supported in part by SBIR Grant DE-SC00005589. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A primary technical challenge to the design of a high luminosity muon collider is an effective beam cooling system. An epicyclic twin-helix channel utilizing parametric-resonance ionization cooling has been proposed for the final 6D cooling stage. A proposed design of this twin-helix channel is presented that utilizes correlated optics between the horizontal and vertical betatron periods to simultaneously focus transverse motion of the beam in both planes. Parametric resonance is induced in both planes via a system of helical quadrupole harmonics. Ionization cooling is achieved via periodically placed wedges of absorbing material, with intermittent rf cavities restoring longitudinal momentum necessary to maintain stable orbit of the beam. COSY INFINITY is utilized to simulate the theory at first order. The motion of particles around a hyperbolic fixed point is tracked. Comparison is made between the EPIC cooling channel and standard ionization cooling effects. Cooling effects are measured, after including stochastic effects, for both a single particle and a distribution of particles.
 
 
TUPPD012 Complete Muon Cooling Channel Design and Simulations 1431
 
  • C. Y. Yoshikawa, C.M. Ankenbrandt, R.P. Johnson
    Muons, Inc, Batavia, USA
  • Y.S. Derbenev, V.S. Morozov
    JLAB, Newport News, Virginia, USA
  • D.V. Neuffer, K. Yonehara
    Fermilab, Batavia, USA
 
  Considerable progress has been made in developing promising subsystems for muon beam cooling channels to provide the extraordinary reduction of emittances required for an energy-frontier muon collider. However, it has not yet been demonstrated that the various proposed cooling subsystems can be consolidated into an integrated end-to-end design. Presented here are concepts to address the matching of transverse emittances between subsystems through an extension of the theoretical framework of the Helical Cooling Channel (HCC), which allows a general analytical approach to guide the transition from one set of cooling channel parameters to another.  
 
TUPPD033 Conceptual Design of a Positron-annihilation System for Generation of Quasi-monochromatic Gamma Rays 1476
 
  • R.J. Abrams, C.M. Ankenbrandt, K.B. Beard, G. Flanagan, R.P. Johnson, C. Y. Yoshikawa
    Muons, Inc, Batavia, USA
  • A. Afanasev
    GWU, Washington, USA
 
  A conceptual design is presented for a system consisting of the following: an electron accelerator and production target to produce positrons, a dipole magnet and wedge to compress the positron momenta to be nearly monochromatic, a magnetic transport system to focus and direct the positrons to a converter, and a converter in which the positrons annihilate in flight to produce quasi-monochromatic gamma rays. The system represented is designed to produce ~10 MeV gammas, but it can also be designed for other energies.  
 
TUPPD083 Raising Photoemission Efficiency with Surface Acoustic Waves 1596
 
  • A. Afanasev, F. Hassani, C.E. Korman
    GWU, Washington, USA
  • V.G. Dudnikov, R.P. Johnson
    Muons, Inc, Batavia, USA
  • M. Poelker, K.E.L. Surles-Law
    JLAB, Newport News, Virginia, USA
 
  Funding: Supported in part by DOE STTR Grant DE-SC0006256. Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
We are developing a novel technique that may help increase the efficiency and reduce costs of photoelectron sources used at electron accelerators. The technique is based on the use of Surface Acoustic Waves (SAW) in piezoelectric materials, such as GaAs, that are commonly used as photocathodes. Piezoelectric fields produced by the traveling SAW spatially separate electrons and holes, reducing their probability of recombination, thereby enhancing the photoemission quantum efficiency of the photocathode. Additional advantages could be increased polarization provided by the enhanced mobility of charge carriers that can be controlled by the SAW and the ionization of optically-generated excitons resulting in the creation of additional electron-hole pairs. It is expected that these novel features will reduce the cost of accelerator operation. A theoretical model for photoemission in the presence of SAW has been developed, and experimental tests of the technique are underway.
 
 
WEOBA03 Beam Tests of a High Pressure Gas-Filled Cavity for a Muon Collider 2131
 
  • T.A. Schwarz, M.A. Leonova, A. Moretti, M. Popovic, A.V. Tollestrup, K. Yonehara
    Fermilab, Batavia, USA
  • M. Chung
    Handong Global University, Pohang, Republic of Korea
  • B.T. Freemire, P.M. Hanlet, Y. Torun
    IIT, Chicago, Illinois, USA
  • R.P. Johnson
    Muons, Inc, Batavia, USA
 
  Funding: US DOE under contract DE-AC02-07CH11359.
One of the greatest challenges in constructing a Muon Collider is cooling the hot muons into a focused beam after their production. Because the beam must be cooled quickly before the muons decay, compact cooling designs require high gradient cavities inside strong magnetic fields. Unfortunately, due to focused field emission, an external magnetic field degrades the performance of the cavity below what is required for a muon collider. High-pressure gas inside the cavity has been proposed to both mitigate this effect, as well as serve as an absorber for transversely cooling the muon beam. A prototype of a high pressure gas-filled cavity is currently being studied at the Muon Test Area at Fermilab. The experimental setup as well as several measurements of the physics and performance of the apparatus while operating in a 400-MeV proton beam will be discussed.
 
slides icon Slides WEOBA03 [6.912 MB]  
 
WEPPC059 A Two-stage Injection-locked Magnetron for Accelerators with Superconducting Cavities 2348
 
  • G.M. Kazakevich, G. Flanagan, R.P. Johnson, F. Marhauser, M.L. Neubauer
    Muons, Inc, Batavia, USA
  • B. Chase, S. Nagaitsev, R.J. Pasquinelli, N. Solyak, V. Tupikov, D. Wolff, V.P. Yakovlev
    Fermilab, Batavia, USA
 
  Funding: Supported in part by SBIR Grant 4743 11SC06261
A concept for a two-stage injection-locked CW magnetron intended to drive Superconducting Cavities (SC) for intensity-frontier accelerators has been proposed. The concept is based on a theoretical model that considers a magnetron as a forced oscillator; the model has been experimentally verified with a 2.5 MW pulsed magnetron. The two-stage CW magnetron can be used as a RF power source for Fermilab’s Project-X to feed separately each of the SC of the 8 GeV pulsed linac. For Project-X the 1.3 GHz two-stage magnetron with output power of 20-25 kW and expected output/input power ratio of about 35-40 dB would operate in a quasi-CW mode with a pulse duration ≤ 10 ms and repetition rate of 10 Hz. The magnetrons for both stages should be based on the commercial prototypes to decrease the cost of the system. An experimental model of the two-stage CW S-band magnetron with peak power of 1 kW, with pulse duration of 1-10 ms, has been developed and built for study. A description of the theoretical and experimental models, simulations, and experimental results are presented and discussed in this work.
 
 
WEPPC060 A High-power 650 MHz CW Magnetron Transmitter for Intensity Frontier Superconducting Accelerators 2351
 
  • G.M. Kazakevich, G. Flanagan, R.P. Johnson, F. Marhauser, M.L. Neubauer
    Muons, Inc, Batavia, USA
  • B. Chase, S. Nagaitsev, R.J. Pasquinelli, V.P. Yakovlev
    Fermilab, Batavia, USA
  • T.A. Treado
    CPI, Beverley, Massachusetts, USA
 
  A concept of a 650 MHz CW magnetron transmitter with fast control in phase and power, based on two-stage injection-locked CW magnetrons, has been proposed to drive Superconducting Cavities (SC) for intensity-frontier accelerators. The concept is based on a theoretical model considering a magnetron as a forced oscillator and experimentally verified with a 2.5 MW pulsed magnetron. To fulfill fast control of phase and output power requirements of SC accelerators, both two-stage injection-locked CW magnetrons are combined with a 3-dB hybrid. Fast control in output power is achieved by varying the input phase of one of the magnetrons. For output power up to 250 kW we expect the output/input power ratio to be about 35 to 40 dB in CW or quasi-CW mode with long pulse duration. All magnetrons of the transmitter should be based on commercially available models to decrease the cost of the system. An experimental model using 1 kW, CW, S-band, injection-locked magnetrons with a 3-dB hybrid combiner has been developed and built for study. A description of the model, simulations, and experimental results are presented and discussed in this work.  
 
WEPPP005 Progress on Muon Parametric-resonance Ionization Cooling Channel Development 2729
 
  • V.S. Morozov, Y.S. Derbenev
    JLAB, Newport News, Virginia, USA
  • A. Afanasev
    GWU, Washington, USA
  • K.B. Beard, R.P. Johnson
    Muons, Inc, Batavia, USA
  • B. Erdelyi, J.A. Maloney
    Northern Illinois University, DeKalb, Illinois, USA
 
  Funding: Supported in part by DOE SBIR grant DE-SC0005589. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Parametric-resonance Ionization Cooling (PIC) is intended as the final 6D cooling stage of a high-luminosity muon collider. To implement PIC, a continuous-field twin-helix magnetic channel was developed. A 6D cooling with stochastic effects off is demonstrated in a GEANT4/G4beamline model of a system where wedge-shaped Be absorbers are placed at the appropriate dispersion points in the twin-helix channel and are followed by short rf cavities. To proceed to cooling simulations with stochastics on, compensation of the beam aberrations from one absorber to another is required. Initial results on aberration compensation using a set of various-order continuous multipole fields are presented. As another avenue to mitigate the aberration effect, we optimize the cooling channel’s period length. We observe a parasitic parametric resonance naturally occurring in the channel’s horizontal plane due to the periodic beam energy modulation caused by the absorbers and rf. We discuss options for compensating this resonance and/or properly combining it with the induced half-integer parametric resonance needed for PIC.
The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.
 
 
THPPC028 Kinetic Modeling of RF Breakdown in High-Pressure Gas-filled Cavities 3341
 
  • D. Rose, C.H. Thoma
    Voss Scientific, Albuquerque, New Mexico, USA
  • J.M. Byrd, D. Li
    LBNL, Berkeley, California, USA
  • R.P. Johnson, M.L. Neubauer, R. Sah
    Muons, Inc, Batavia, USA
  • A.V. Tollestrup, K. Yonehara
    Fermilab, Batavia, USA
 
  Funding: Supported in part by USDOE STTR Grant DE-FG02-08ER86352
Recent studies have shown that high gradients can be achieved quickly in high-pressure gas-filled cavities without the need for long conditioning times, because the dense gas can dramatically reduce dark currents and multipacting. In this project we use this high pressure technique to suppress effects of residual vacuum and geometry found in evacuated cavities to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of radiofrequency and surface preparation. A series of experiments at 805 MHz using hydrogen fill pressures up to 0.01 g/cm3 of H2 have demonstrated high electric field gradients and scaling with the DC Paschen law limit, up to ~30 MV/m, depending on the choice of electrode material. For higher field stresses, the breakdown characteristics deviate from the Paschen law scaling. Fully-kinetic 0D collisional particle-in-cell (PIC) simulations give breakdown characteristics in H2 and H2/SF6 mixtures in good agreement with the 805 MHz experimental results below this field stress threshold. The impact of these results on gas-filled RF accelerating cavity design will be discussed.
 
 
THPPC032 Conditioning and Future Plans for a Multi-purpose 805 MHz Pillbox Cavity for Muon Acceleration 3353
 
  • G.M. Kazakevich, A. Dudas, G. Flanagan, R.P. Johnson, F. Marhauser, M.L. Neubauer, R. Sah
    Muons, Inc, Batavia, USA
  • S.S. Kurennoy
    LANL, Los Alamos, New Mexico, USA
  • A. Moretti, M. Popovic, G.V. Romanov, K. Yonehara
    Fermilab, Batavia, USA
  • Y. Torun
    IIT, Chicago, Illinois, USA
 
  Funding: Supported in part by grant 4735 · 10 LANL and Dept. of Energy STTR grant DE-FG02-08ER86352.
An 805 MHz RF pillbox cavity has been designed and constructed to investigate potential muon beam acceleration and cooling techniques for a Muon Collider or Neutrino Factory. The cavity can operate in vacuum or under pressure to 100 atmospheres, at room temperature or in a liquid nitrogen bath at 77 K. The cavity has been designed for easy assembly and disassembly with bolted construction using aluminum seals. To perform vacuum and high pressure breakdown studies of materials and geometries most suitable for the collider or factory, the surfaces of the end walls of the cavity can be replaced with different materials such as copper, aluminum, beryllium, or molybdenum, and with different geometries such as shaped windows or grid structures. The cavity has been designed to fit inside the 5-Tesla solenoid in the MuCool Test Area at Fermilab. In this paper we present the vacuum conditioning results and discuss plans for testing in a 5-Tesla magnetic field. Additionally, we discuss the testing plan for beryllium (a material research has shown to be ideal for the collider or factory) end walls.
 
 
THPPD041 Evaluation and Implementation of High Performance Real-Time Signal Processing For Rayleigh Scattering Based Quench Detection for High Field Superconducting Magnets 3602
 
  • G. Flanagan, R.P. Johnson
    Muons, Inc, Batavia, USA
  • W.K. Chan, J. Schwartz
    North Carolina State University, Raleigh, North Carolina, USA
  • Q. Ruan, D. Schmidt, L. Wenzel, C. Wimmer
    National Instruments, Austin, USA
 
  Funding: Supported in part by SBIR Grant 4747 · 11SC06251
YBCO coated conductors are one of the primary options for generating the high magnetic fields needed for future high energy physics devices. Due to slow quench propagation, quench detection remains one of the primary limitations to YBCO magnets. Fiber optic sensing, based upon Rayleigh scattering, has the potential for quench detection with high spatial resolution. This paper discusses the potential of multicore CPU's and FPGA’s to accelerate the signal processing demands associated with Rayleigh scattering based quench detection systems in a real-time environment.
 
 
THPPD045 High Temperature Superconducting Magnets for Efficient Low Energy Beam Transport Systems 3614
 
  • J.H. Nipper, G. Flanagan, R.P. Johnson
    Muons, Inc, Batavia, USA
  • M. Popovic
    Fermilab, Batavia, USA
 
  Modern ion accelerators and ion implantation systems need very short, highly versatile, Low Energy Beam Transport (LEBT) systems. The need for reliable and continuous operation requires LEBT designs to be simple and robust. The energy efficiency of available high temperature superconductors (HTS), with efficient and simple cryocooler refrigeration, is an additional attraction. Innovative, compact LEBT systems based on solenoids designed and built with high-temperature superconductor will be developed using computer models and prototyped. The parameters will be chosen to make this type of LEBT useful in a variety of ion accelerators, ion implantation systems, cancer therapy synchrotrons, and research accelerators, including the ORNL SNS. The benefits of solenoids made with HTS will be evaluated with analytical and numerical calculations for a two-solenoid configuration, as will be used in the SNS prototype LEBT that will replace the electrostatic one at SNS, and a single solenoid configuration, as was proposed for the Fermilab proton driver that will be most applicable to ion implantation applications.  
 
THPPR062 Handling GEM*STER Volatile Radioactive Fission Products 4115
 
  • M. Notani, C.M. Ankenbrandt, R.P. Johnson, T.J. Roberts
    Muons, Inc, Batavia, USA
  • C. Bowman
    ADNA, Los Alamos, New Mexico, USA
 
  A next-generation advanced technology of nuclear power has been developed for many years. One of the promising future reactor designs with accelerator-produced neutrons is GEM*STAR (Green Energy Multiplier*Subcritical Technology for Alternative Reactors) developed by Accelerator Driven Neutron Application (ADNA), which is a subcritical thermal-spectrum reactor operating with molten salt fuel in a graphite matrix. GEM*STAR is able to use natural uranium as well as unreprocessed spent fuel from light-water reactors (LWR), generating as much electricity as the LWR had generated from the same fuel. Since the advanced design of GEM*STAR is quite different from LWR that uses solid nuclear fuel loaded in the Zircaloy, it requires emission control for volatiles emitted from the molten salt fuel, like as radioactive iodine and cesium. The volatiles caught in the helium gas circulating around the core reactor will be trapped in the cryogenic bottles. Numerical simulations to estimate the amount of fission products were performed for the design of confinement of the volatiles. The result of simulation with spent nuclear fuel from LWR is presented.