AHF MAGNETIC LENS CRYOSYSTEMS[Advanced Hydrotest Facility] Page: 3 of 8

TABLE 1. Lens Magnets' Cryogenic Parameters

Ambient Pressure @ LANL (atm)
Length (m)
Bore (m)
Number with (without) Monitor Lenses
Primary Supply System
Type of Cooling
Nominal Operating Temperature (K)
Nominal Operating Pressure (atm)
Heat Load - Calculated (Used) (W)
Operating Current (A)
Liquefaction Load (Power Leads)
Lead Type
Massflow (lead pair) (g/s)
Inlet Temperature (K)
Outlet Temperature (K)
Inlet Pressure (atm)
Outlet Pressure (atm)
Secondary (Shield) Supply System
Type of Cooling
Nominal Inlet Temperature (K)
Nominal Outlet Temperature (K)
Max. Allowable Pressure (atm)
Heat Load - Calculated (Used) (W)

Small Lens
Condenser
Magnet
0.8
2.52
0.203
8
Pool Boiling
4.43
1.125
7.49 (10)
7800
Vapor Cooled
0.87
4.43
- 300
1.125
0.85
GHe
40
< 55
20
33.76 (44)

Small Lens Large Lens
Magnet Condenser
Magnet
0.8 0.8
2.90 2.79
0.229 0.483
96 (64) 4

Pool Boiling
4.43
1.125
9.71 (10)
7800
Vapor Cooled
0.87
4.43
- 300
1.125
0.85
GHe
40
< 55
20
43.73 (44)

Pool Boiling
4.43
1.125
19.78 (20)
7800
Vapor Cooled
0.87
4.43
- 300
1.125
0.85
GHe
40
< 55
20
89.08 (90)

Large Lens
Magnet

0.8
4.12
0.483
48 (32)
Pool Boiling
4.43
1.125
29.13 (30)
7800
Vapor Cooled
0.87
4.43
- 300
1.125
0.85
GHe
40
< 55
20
131.20 (132)

1. The first sets of elements, the eyepiece and condenser magnets serve to expand the beam
to a size appropriate for object illumination. Monitor lenses, each consisting of four
quadrupoles, which identically transfer the expanded beam onto the object, follow the
condenser magnets and are located just upstream of the study object. The monitor lenses
provide a means of measuring beam properties at a distance from the object. Although the
monitor lenses are a baseline of the project, alternative means of beam diagnostic are
possible. If monitor lenses are not included, the condenser and eyepiece magnets are
moved closer to the object. Two lenses sets, each consisting of four quadrupoles, are
located immediately downstream of the study object. Each set provides an image of the
object. Adjoining pairs of quadrupoles share the same cryostat. The magnets of each four-
quadrupole lens set are powered serially. Finally, the condenser and eyepiece magnets are
independently powered.
The lens SC elements are the lens magnets (small and large bore) and condenser
magnets (small and large bore). The eyepiece magnets are normal conducting and operate
at room temperature. TABLE 1 presents the parameters used to develop a baseline
cryosystem for the SC magnet lens system. The low atmospheric pressure of Los Alamos,
elevation 7,000 ft. (2,100 m) above sea level, allows magnet operation at temperatures
below 4.5 K without warm vacuum pumping or cold compressors. The lower operating
temperature permits a more aggressive magnet design, a larger quench margin, or some of
each. Magnet heat loads were developed by linearly scaling the measured and calculated
values of the CEBAF (Continuous Electron Beam Accelerator Facility) Hall C quadrupole
magnets [5,6] by length and bore radius. The numbers in the brackets beside the scaled
numbers are the values of heat load used in the cryoplant-sizing calculations. The use of
liquid nitrogen to cool the magnet shields located at tunnel level is avoided to minimize
facility oxygen-deficiency safety concerns. Liquid nitrogen is, however, used to precool the
helium in the grade-level cryoplant.

LA-UR-01-3738

3

Upcoming Pages

Here’s what’s next.

upcoming item: 4 4 of 8
upcoming item: 5 5 of 8
upcoming item: 6 6 of 8
upcoming item: 7 7 of 8

Show all pages in this article.

This article can be searched. Note: Results may vary based on the legibility of text within the document.

Tools / Downloads

Get a copy of this page .

Citing and Sharing

Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.

Reference the current page of this Article.

KELLEY, J. P. & MULHOLLAND, G. T. AHF MAGNETIC LENS CRYOSYSTEMS[Advanced Hydrotest Facility], article, June 1, 2001; New Mexico. (digital.library.unt.edu/ark:/67531/metadc721057/m1/3/ocr/: accessed November 16, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.

International Image Interoperability Framework (This Page)