high power beam dump hall a

High Power Beam DumpHall A

June, 2014Tim Michalski

Overall Hall Dump Requirements

SectionTitle Requirement Comments1.1.1 Beam Dump Overall

Requirements

1.1.1.1 Provide reliable, safe disposition of the electron beams in halls A and C.

1.1.1.2 Minimize maintenance 1.1.1.3 Minimize accelerator down time 1.1.1.4 Minimize radiation production and exposure to

personnel

1.1.1.5 Beam Energy 1 - 11 GeV 1.1.1.6 Beam Power Up to 1000 kW 1.1.1.7 Beam Current Up to 200 µA (limited by power specification) 1.1.1.8 Minimum Beam Size 2σ radius 400µm – up to 50 uA

5mm2 raster > 50uAVacuum window and diffuser capability limits

1.1.1.9 Current Density Limit 12.5 µA/cm2 in the +/- 4 cm area of the dump face

Defined by the limits of the dump window.

1.1.1.10Power Density Limit 62.5 kW/cm2 Defined by the limits of the dump heat exchanger - 1 MW beam in 16cm2

Helium Tube

BPIC / Flange Spacer (Optional)

Helium Purge

Helium Fill

High Power Viewer

Flange w/ coated window – prevents N2 from back-flowing into hall

.010” Thick Aluminum viewer screen – coated with .001”-.002” thick layer of aluminum oxide ceramic (grey alumina) – Mounted to mirror box for alignment and stability

Diffuser RequirementsSection Title Requirement Comments3.3.1 Diffuser Existing assemblies:

Hall C - 67172-D-56104 rev AHall A - there does not appear to be an assembly document for this????

3.3.1.1 Purpose and basic function of the device

Convert 11.1 GeV, 90 uA, 100x100 micron^2 unrastered beam into the spot at the dump with the maximum current area density below the requirement - 1.1.1.9 - Current Density Limit - 12.5 µA/cm2 in the +/- 4 cm area of the dump face (defined by the limits of the dump window).1.1.1.10 – Power Density Limit - 62.5 kW/cm2 (defined by the limits of the dump heat exchanger - 1 MW beam in 16cm2).The Diffuser must prevent this current density for all beam/target conditions.Also convert 1.1 GeV, 200uA rastered beam, which has been scattered by a target, to a spot size which is safe for the dump.

Tech Note (TN-???) describes in detail the range of performance parameters levied on the diffuser. The range of beam energies, beam currents, and target materials/thicknesses cannot be resolved by a single radiation length diffuser. Therefore, the decision has been made to accommodate 4 setting.

3.3.1.2 Spot Size at the Dump 4" Diameter - requires selection of the appropriate diffuser RL in conjunction with the target, energy, and current.

Per Flared and Dished Head - End Station Beam Dump drawing number 27020-E-0023 rev A

3.3.1.3 Position in the beamline/dump assembly

Between the end of the helium tube and the end of the vacuum for the beamline in the hall. Approximately 56.5 feet upstream of the beam dump vessel assembly.

Consider activation potential based on material and location. Ideally, it should be placed as deep in the dump tunnel to protect from activation issues.Consider proximity to beam scrape plate and IC test plate for scattering from diffuser.

3.3.1.4 Material Aluminum – multiple sheets in series to achieve the desired radiation length for the 3 settings (4th setting is no diffuser)

Considerations for material are the neutron production versus Radiation Length versus material. Considered several options: Be, W, Pb/Diamond, Graphite

3.3.1.5 Heat Load Will depend on material and thickness. Final design will dictate this value – peak of 4,800 watts

Historically, water cooled diffusers have been used.

3.3.1.6 Cooling Method and Requirements

Distributed heating via oscillating the diffuser. Secondary cooling is forced convection of N2 gas via blower and jet/nozzle.

3.3.1.7 Max and Min Beam Energy/Beam Current

11.1 GeV, 90 uA, 100x100 micron^2 unrastered beam 2.2 GeV, 200uA rastered beam

It may be desirable to modify or replace the diffuser window thickness due to different beam conditions.

3.3.1.8 Acceptance Should be fairly large (6-10 cm radius) Purpose is to avoid differential heating or beam impingement on the support structure.

3.3.1.9 Design Considerations a) As robust as possible.b) Facilitates rapid replacement.c) May serve as part of the high power viewer systemd) Due to the potentially high activation, look at the diffuser having a "storage" position which places it into a shielded area - prevents inadvertent contact and a measure of shielding.

3.3.1.10 Control Requirements Remote control - Must be controllable and monitored from the MCC.

At a prior concept review, it was decided that the MCC must be able to CONFIRM POSITION of the Diffuser. Lock & Tag – Confirm. Remote control is not required.

3.3.1.11 Interlocks, FSD, Instrumentation

a) Method for determining which RL diffuser is insertedb) Communication of diffuser setting to MCCc) Is there a need to have FSD or MPS for this?

Required if automated.Requirement from the Concept Review is that the position of the Diffuser must be confirmed and communicated – recommend Lock, Tag, & Confirm

Diffuser Thickness Determination

• Low Energy – no diffuser• 3 additional RL thickness

diffuser segments• Covers full beam energy

spectrum with overlap• Will require assessment

during ERR

Diffuser• 4 position settings – set in the

hall• Stacked aluminum plates –

weight, cost, ease of manufacture

• Oscillates at .1 Hz to distribute power density

• Supplemental forced convection cooling for robust, long life

• Graphalloy bearings – no lubricant for survival in radiation environment

• Storage in lead block shielding when accessing past the Isolation Wall

• Re-use existing stands to support the diffuser and shielding blocks

Diffuser

Diffuser, Vac Window, Aperture Plate Cooling• Forced Convection – Diffuser and Vacuum Window• Perimeter Water Cooling – Vacuum Window and Aperture

Plate

Isolation Wall

Looking Downstream Looking Upstream

Vacuum WindowSection Title Requirement Comments3.1.4 Vacuum Window

3.1.4.1 Beam Parameters Imparted on Vacuum Window

a) 50 uA, 400 micron diameter (no target, no raster, CW)b) Up to 200 uA, 1 cm^2 round spot size (requires a combination of target and raster)

Need MPS for beam current exceeding 50 uA - requiring raster and target.

3.1.4.2 Material Material selection should be metallic and capable of withstanding the maximum design current without exceeding thermal or stress limits. Material selection will be dependent upon simultaneously satisfying these criteria.

3.1.4.3 Cooling Cooling method in order of decreasing desire:1) Passive cooling (natural convection, conduction)2) Forced convection3) Edge cooled liquid cooling4) Flow over liquid cooling (flow between two plates)

Will require a combination of Edge Cooled Liquid Cooling and Forced Convection on the Face

3.1.4.4 Minimum OD 40 cm (15.75") to flange Minimum clearance of 20 cm to thick sections (e.g. flange) and hardware.

3.1.4.5 Pressure Load Vacuum - 1 atm (14.7 psi)

3.1.4.6 Design Considerations

a) Design for a maximum allowable current with minimum beam diameterb) Removable without going behind shield wallc) Ease of removal (ALARA)d) Minimize opportunities for leaks (joints, etc.)

Determine max current design without rastering or target. Anything above that current requires interlocks for raster, target, etc. by the hall.

3.1.5 Seal to Isolation Wall

Leak tight to better than of 75cc/min at 2" of H2O delta pressure (.07 psi)

Vacuum Window – Analysis Parameters• Goal to keep material stress

below yield strength of 5052-O

• 200 W/m2K forced convection on exterior face

• Evaluate beam current vs spot size vs stress limits

Vacuum Pipe Design Details

45” Flange Interface

Tune-Mode Viewer

Aperture Plate w/ 3” Center Hole – water cooled

Calibration “Puck” – 1mm thick Tungsten

Vacuum Window – water cooled

Vacuum Pipe Vacuum Analysis• Analyzed for Vacuum and Buckling

VACUUM:Stress and displacement are acceptable at .125” wall thickness 5052-O Aluminum

BUCKLING:• Requires stiffening

ribs to get to a SF=2

• Recommend stiffening ribs and an increased wall thickness to .188” (SF=3)

Ion Chambers / Calibration System / Aperture Plate

Aperture Plate• 5% Target, 1 GeV, 200 uA – 1571 W

– Worst Case• Also evaluated:

– 10% Target, 1 GeV, 200 uA– 1% Target , 1 GeV, 200 uA– .5% Target, 1 GeV, 200 ua

Tune Mode Viewer

Diagnostics, Controls, Monitoring

Status / Schedule• Goal to have all material here by end of July

– By end of this week, all material on order except diffuser parts and isolation wall

– Vacuum Pipe due July 17th

• Leaking dump flange repaired last week – need to leak test with 1st section of He pipe

• Facilities has a plan for N2 generation and modified exhaust system – need schedule details

• Modification and reassembly of He pipe complete by end of July

• Diffuser, isolation wall, viewers, vacuum pipe installation planned for August

• Installation of PSS, FSD, I&C, monitoring, EPICS screens - Sept

high power beam dump hall a

Documents

dump window

mw beam

beam currents

unrastered beam

beam energy1

beam powerup

beam dump vessel assembly

dump facedefined