Asynchronous Beam Dump

Transcription

1 L. Keller, SLAC Phase 2 Specification and Implementation Meeting, 28 November, 28 Asynchronous Beam Dump Impact Secondary Collimator 7 TeV Estimate Energy Deposition and Instantaneous Temperature Rise in Downbeam Absorber Jaws

2 SLAC Damage Test Beam entering a few mm from the edge of a 3 cm long copper block The length and depth of this melted region is comparable to the ANSYS simulation for the LHC accident. 3 cm 5 kw beam.65 MJ in 1.3 sec copper Beam diameter ~ 2 µ It took about 1.3 sec to melt thru the 3 cm block, but for this relatively large beam, the front two radiation lengths remain intact.

3 Accident Simulation 6R7 Method: 1. Start with 23 mis-steered bunches at the location of TCSG.6R7 (or TCSM.6R7) with centroids ranging from σ x to σ x. Each bunch has σ x =.44 cm and σ y =.152 cm. 2. With the horizontal gap in 6R7 set to 7 σ x (.283 cm), transport each bunch toward 6R7. Place a 1 σ x cut on all trajectories entering 6R7, i.e. assume that any proton > 1 σ x does not reach collimator 6R7. Set the absorber half-gaps = 1 σ 3. Using the FLUKA IR-7 model (checked with TURTLE), find that: 11 bunches with centroids from 5.8 to σ x contribute hits on TCSG.6R7 (this is equivalent to 4.2 full intensity bunches or 4.6 x 1 11 protons). 4. With FLUKA, record the energy deposited in small volume elements of the four tungsten absorbers by each of the 11 bunches hitting 6R7. This gives the instantaneous temperature rise throughout the tungsten absorber jaws.

4 FLUKA Simulation Model MQTLHA/B dipoles MBW1A/B dipoles MBW1C/D 4.2 equiv. bunches hit 6R7 TCLA.A6R7 Vert. gap TCLA.E6R7 Vert. gap TCLA.F6R7 TCSG.6R7 TCLA.C6R7 X (cm) TCSM.6R meters from TCSG.6R7

5 Longitudinal Temperature in TCLA.A6R7 - Accident Hitting TCSG.6R7 - Phase equivalent bunches hit TCSG.6R7, 7 to 1 σ x Phase 1 Peak Temperature in TCLA.A6R7, Top Jaw Mis-steering Accident Hits TCSG.6R7 (carbon) 7 TCLA.A6R7 half-gap = 1 σ Bin volume is.4 x.25 x 1 cm Tungsten temperature (deg C) Longitudinal melt region 3 cm tungsten melt, 31 deg C tungsten fracture, 7 deg C top jaw Z (cm)

6 Temperature Distribution in TCLA.A6R7 at Shower Maximum, Phase equivalent bunches hit TCSG.6R7, 7 to 1 σ x melt or fracture region (zoom in next slide) Y (cm) X (cm) Degrees Centigrade

7 Temperature Distribution in TCLA.A6R7 at Shower Maximum, Phase equivalent bunches hit TCSG.6R7, 7 to 1 σ x Y (cm) beam axis X (cm) melt >31 fracture >7

8 Temperature Distribution in TCLA.A6R7 at Shower Maximum, Phase equivalent bunches hit TCSG.6R7, 7 to 1 σ x TCLA.A6R7 Horizontal Temperature Dist. Tungsten Temperature (deg C) top jaw X (cm) Horizontal melt region.8 cm at shower max. TCLA.A6R7 Vertical Temperature Dist. Tungsten Temperature (deg C) bottom jaw Y (cm) top jaw Vertical melt region.3 cm at shower max.

9 Longitudinal Temperature in TCLA.C6R7 - Accident Hitting TCSG.6R7 - Phase equivalent bunches hit TCSG.6R7, 7 to 1 σ x 5 Phase 1 Peak Temperature in TCLA.C6R7, Left Jaw Mis-steering Accident Hits TCSG.6R7 (carbon) TCLA.C6R7 half-gap = 1 σ Bin volume is.8 x.25 x 1 cm 4 Tungsten temperature (deg C) left jaw Z (cm )

10 Longitudinal Temperature in TCLA.A6R7 - Accident Hitting TCSM.6R7 - Phase equivalent bunches hit TCSM.6R7, 7 to 1 σ x Phase 2 Peak Temperature in TCLA.A6R7, Top Jaw Mis-steering Accident Hits TCSM.6R7 (copper) Tungsten temperature (deg C) TCLA.A6R7 half-gap = 1 σ Bin volume is.4 x.25 x 1 cm top jaw Z (cm)

11 Longitudinal Temperature in TCLA.C6R7 - Accident Hitting TCSM.6R7 - Phase equivalent bunches hit TCSM.6R7, 7 to 1 σ x Phase 2 Peak Temperature in TCLA.C6R7, Left Jaw Mis-steering Accident Hits TCSM.6R7 (copper) Tungsten temperature (deg C) Z (cm) TCLA.C6R7 half-gap = 1 σ Bin volume is.8 x.25 x 5 cm left jaw

12 Summary 1. This was a FLUKA simulation of an asynchronous beam dump in which an equivalent of 4.2 full intensity bunches impact secondary collimator TCS.6R7. 2. In Phase 1 (6R7 carbon) enough energy is deposited in the nearest tungsten absorber, TCLA.A6R7, to cause melting in the top and bottom jaws over a considerable volume. Each jaw of TCLA.A6R7 receives 8 kj. There appears to be no damage to absorbers further downstream. 3. In Phase 2 (6R7 copper) there is no damage to any of the four tungsten absorbers. The highest temperature reached in TCLA.A6R7 is 15 C. Each jaw of TCLA.A6R7 receives 2 kj.