The 14th Symposium on Accelerator Science and Technology, Tsukuba, Japan, November 2003

A 4 0 0 m -L O N G S U P E R C O N D U C T I N G R F L I N A C C R Y O S T A T D E S I G N
F O R A N E R L L IG H T SO U R C E
Eisuke. J . Minehara, FEL Laboratory at Tokai, JAERI, 2-4 Tokai, Ibaraki, 319-1195 JAPAN

Abstract

cavity N o—a^beampipe No

3 0H

In order' to realize quickly an industrial energy
recovery linac (ERL) light source, a 400m-longsuperconducting RF linac cryostat is conceptuallydesigned and discussed to optimize major opa^ational
characteristics of the advanced low-temperature cryostat foran. ERL light source near futurc. A low temperaturecryostat for superconducting RF linacs and othersuperconducting devices should be designed and made tominimize its heat invasion through the heat bridges
between the room and low temperature parts. The
cryostat also should be designed and made to minimize
total number of the heat cycles for the rest of its life ofter
the initial test. We can expect that the total nmnba- ofthe heat bridges is roughly proportional to the number of
the ayostat，and a life interval between two contiguous
cryostat maliunctions inversely proportional to thenumber of the heat cycles. Therefore, if we can design
and make a single and long cryostat to realize theoperation less than a half cycle for the rest of its life, wecan run our cryostat for a very longer interval than tens ofyears and with minimum electricity. In adition to them,we plan to summarize the JAERI ERL FEL zero-boil off
cryostat design, its operational characteristics, and non­stop operation records over these 12 years and othercryostat related activities in the poster presentation.
Each ayostat usually has one or two liquid He feeding
ports, and two beam pipes，several RF main and higher
mode couplers. Here we assumed that the ERL has 800
cavities, 400m accelerating length, average acceleration
gradient of 10-15MeV/m, and total electron energy 46GeV. Horizontal axis is number of cavities installed ineach cryostat, vertical one total static heat load Minimal•■■金圖HePipeN o一u

CRYOSTAT CONSIDERATION FOR
INDUSTRIAL ERL LIGHT SOURCES

Cryostat Heat Load10000EA so-called 4th generation synchrotron radiation
light source for a large-scale user facility like the 3rd ones
has been recently cfiscussed to realize using asuperconducting RF linac-based FEL [ 1 ] or an energy
reooveiy linac (ERL) light source [2]. In order to realizeboth of them， we need veiy large number of lowtemperature cryostats to run them routinely and efficiently.
A 400m-long superconducting RF linac cryostat isconceptually designed here and discussed to optimize
major operational characteristics of the advanced lowtemperature cryostat for an ERL light source near future.

static heat load will be realized if we can choose a single
and longest cryostat, and the maximum load the shortestcryostat. Because we intend to use the cryostat for thei#-RFCNop80—O—Total Heatload p80-^-.R]FCNop20：—A —TotaJJHeat
load<p20-W -RFCNop2

10100

1000

Total Heatload p2

No. Crostat
Fieure. Static Crvostat Heat Load and No. of Crvostat.

ERL, RF power for the main acceleratoi. linac will berecovered and the power supply will feed a large numba*of cavities. In the figure, there arc 3 cases of cavity
number fed by oneRF port, i.e .,1 , 4, and 40, and "Total
Heat Loa(^80% "Total Heal Loadp20' and "Total Heat
Loa(|}2” indicate them respectively.. The maximum heatload became 3.2kW at low temperature, and the minimum
24W.
Heat shield of the long and single ayostat will becooled down by using integrated reMgeralors system like
existing JAERI zero-boil off cryostat system [3].

REFERENCES[1 ]TESLA Technical Design Report, DESY 2001-011,
March 2001.
[2] LV.Bazaiov et d ” *The energy recovery linac (ERL)
as a driver for X-ray.
[3] E.J.Minehara et al., ppl59-161, in the proceedings ofParticle Accelerator Conference, 1995, Dallas.
E.J.Minehara et al., Free Electron Laser Challenge2(SPffi) Vol.3614, pp.62-71, 1999.
EJMineham et al” Nucl. Instrum. Methods Phys. Res.
Sect.A445,183 (2000).